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A combined experimental (IR, Raman and UV–Vis) and quantum chemical study of canadine
Accepted Manuscript A combined experimental (IR, Raman and UV–Vis) and quantum chemical study of canadine
Bhawani Datt Joshi, Anubha Srivastava, Poonam Tandon, Sudha Jain, A.P. Ayala PII: DOI: Reference:
S1386-1425(17)30807-7 doi:10.1016/j.saa.2017.10.008 SAA 15514
To appear in:
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
Received date: Revised date: Accepted date:
9 February 2017 3 September 2017 3 October 2017
Please cite this article as: Bhawani Datt Joshi, Anubha Srivastava, Poonam Tandon, Sudha Jain, A.P. Ayala , A combined experimental (IR, Raman and UV–Vis) and quantum chemical study of canadine. The address for the corresponding author was captured as affiliation for all authors. Please check if appropriate. Saa(2017), doi:10.1016/ j.saa.2017.10.008
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ACCEPTED MANUSCRIPT A combined experimental (IR, Raman and UV-Vis) and quantum chemical study of canadine Bhawani Datt Joshia,b*, Anubha Srivastavac, Poonam Tandonc*, Sudha Jaind, A. P. Ayalab a
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Department of Physics, Siddhanath Sc. Campus, Tribhuvan University, 10406, Nepal. b Departamento de Fisica, Universidate Federal do Ceará, C. P. 6030, 60.455-900, Fortaleza, CE, Brasil. c Department of Physics, University of Lucknow, University Road, Lucknow 226 007, Uttar Pradesh, India. d Department of Chemistry, University of Lucknow, University Road, Lucknow 226007, Uttar Pradesh, India
________________________ *Corresponding author. Tel.: +977-9841580777; +91 522 2782653; fax: +91 522 2740840. E-mail address: [email protected], [email protected] (B. D. Joshi), [email protected] (P. Tandon)
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ACCEPTED MANUSCRIPT Abstract Plant based natural products cover a major sector of the medicinal field, as such focus on plant research has been increased all over the world. As an attempt to aid that research, we have performed structural and spectroscopic analysis of a natural product, an alkaloid: canadine. Both ab initio Hartree-Fock (HF) and density functional theory (DFT) employing
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B3LYP using 6-311++G(d,p) basis set were used for the calculations. The calculated
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vibrational frequencies were scaled and compared with the experimental infrared and Raman
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spectra. The complete vibrational assignments were made using potential energy distribution. The structure-activity relation has also been interpreted by mapping electrostatic potential
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surface and evaluating the reactivity descriptors, which are valuable information for quality control of medicines and drug-receptor interactions. Natural bond orbital analysis has also
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been performed to understand the stabilty and hyperconjogative interactions of the molecule. Furthermore, UV-Vis spectra have been recorded in an ethanol solvent (EtOH) and the
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electronic property has been analyzed employing TD-DFT for both gaseous and solvent
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phase. The HOMO and LUMO calculation with their energy gap show that charge transfer occurs within the molecule. Additionally, the nonlinear optical properties of the title
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compound have been interpreted that predicts it’s the best candidate for the NLO materials.
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Keywords: CAD, ab initio, DFT, vibrational spectroscopy, NBO, NLO properties
1. Introduction Literature reveals the traditional use of medicinal herb Goldenseal (Hydrastis canadensis L., belonging to the genus, Menispermaceae) for mild pathological conditions such as gastritis, colitis, duodenal ulcers, loss of appetite, and liver disease [1-3]. Benzylisoquinoline alkaloids viz; berberine, β-hydrastine, canadine, and canadaline have
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ACCEPTED MANUSCRIPT active components of Goldenseal. Canadine (CAD) possesses ventricular anti-fibrillatory effects (that may be attributed to its blockade of Na+, K+, and Ca2+ currents) [4], a potent inhibitor of platelet aggregation (in vitro and in vivo triggered by ADP, collagen, and arachidonic acid), and promising antithrombotic drug [5]. Having non-quaternary nitrogen and two non-aromatic rings, it has an antioxidant activity [6], and display very low
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cytotoxicity [7]. Algarra et al. [8] analyzed different separation techniques for CAD alkaloid
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in goldenseal extracts. Also, Pingali et al. [3] determined the crystalline structure of canadine
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molecule by single crystal diffraction technique. Its chemical structure is shown in the Fig. 1(a).
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Spectroscopic techniques, when combined with the quantum chemical calculations, are emerging as one of the most valuable methods for studying the structural behavior and to
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gain insight into the electronic structures of alkaloids at microscopic level [9, 10]. As the natural products show a diversity of chemical structures, in the recent years there has been
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increasing interest in the application of ab initio calculations to alkaloids as demonstrated in
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our earlier studies [9, 11, 12] as well as in others [13-16]. The theoretical investigations on the molecular properties can facilitate the solutions confronted in the experimental
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techniques.
A literature search reveals that neither the experimental infrared, Raman, and UV-Vis
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spectral analyses nor the theoretical calculations on molecular geometry, vibrational modes, natural bond orbital (NBO) and nonlinear optical (NLO) properties of the title molecule has been investigated so far. We would like to eliminate this deficiency observed in the literature. The main objective of this study is to investigate the structural and electronic properties of the title compound with the help of vibrational spectroscopic techniques and quantum mechanical calculations using both ab initio Hartree-Fock (HF) and the density functional theory (DFT) [17]. To understand the various conjugative and hyperconjugative interactions
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ACCEPTED MANUSCRIPT as well intermolecular interactions that would form the H-bonded network within the molecule, natural bond orbital (NBO) analysis has been performed. Also, to interpret the structural-activity relationship and reactive sites of the molecule, molecular electrostatic potential (MEP) and reactivity descriptors have been calculated. Further, the nonlinear (NLO)
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property reveals that the title compound can be used as a good NLO material.
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2. Experimental details
Infrared spectra of CAD were recorded on a Bruker TENSOR 27 FT-IR spectrometer
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with a spectral resolution of 4 cm-1 in the region 300-4000 cm-1. Pellets of solid samples were
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prepared from mixtures of KBr and the sample in 200:1 ratio using a hydraulic press. The Raman spectra were recorded using an efficient visible Raman setup, Ar-514 nm,
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and 12 mW, at room temperature. An excitation laser of wavelength 514 nm was emitted from an Argon ion laser source with a power of 12 mW was used to record the vibrational
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spectra. The scattered Raman light was collected in a back scattering geometry using a
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microscope objective (ULW x50). The scattered light was dispersed using a monochromator with 1200 grooves/mm diffraction grating, and an entrance slit width of 200 micrometers.
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The Raman signals were detected using liquid nitrogen cooled charged coupled device (CCD) with an optimal sensitivity in the visible range. The total exposure time for each sample was
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5 sec and averaged over five accumulations. The ultraviolet absorption spectra of the molecule were examined in the range 200800 nm using a Varian - Cary 50 Bio, UV-Vis Spectrophotometer equipped with a 10 mm quartz cell. The UV pattern is taken from a 1x10-5 M solution of CAD, dissolved in ethanol at 20 ˚C.
3. Computational details
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ACCEPTED MANUSCRIPT The molecular structure, vibrational frequencies, and energies of the CAD were computed employing the DFT [17] method using Gaussian 09 program [18] package and Becke’s three parameters (local, non-local, Hartree-Fock) hybrid exchange functional with Lee-Yang-Parr correlation functional (B3LYP) [19-21]. First, the B3LYP/6-311++G(d,p) level of theory has been used for optimization protocol. Using these optimized parameters,
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the vibrational frequencies have been calculated at same level theory, which were used
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further for the spectra simulation. The split valence basis set 6-311++G(d,p) augmented by
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‘d’ polarization functions on heavy atoms and ‘p’ polarization functions on hydrogen atoms as well as diffuse functions for both hydrogen and heavy atoms [23, 24] have been used. The
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absolute Raman intensities and infrared absorption intensities were calculated in the harmonic approximation at the same level of theory as used for the optimized geometries.
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The vibrational assignments of normal modes were performed and the PED was calculated employing Gar2ped program [25] along with the internal coordinates using localized
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symmetry. For this purpose, a complete set of 132 internal coordinates were defined using
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Pulay’s recommendations [26, 27].
The graphical representation of the calculated Raman and IR spectra were made using
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GaussView program [28]. Visualization and confirmation of calculated data were done by using the Chemcraft program [29]. Isoelectronic molecular electrostatic potential surface
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(MEP) was mapped with GaussView program [28] using B3LYP/6-311++G(d,p) basis. Mulliken atomic charges, HOMO–LUMO gap (∆E), ionization potential, dipole moments and total energy have also been obtained for the optimized geometry. A theoretical time dependent density functional theory (TD-DFT) [23, 24] method was used to calculate the electronic absorption parameters in the gas phase, employing 6-31G basis set and the solvent effects (in EtOH solvent) were taken into account by means of integral equation formalism polarizable continuum model (IEF-PCM) [30-32]. NBO [17] analysis, which deals about the
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ACCEPTED MANUSCRIPT intra- and intermolecular charge delocalization between the bonds of a molecular system, has been performed at the DFT/B3LYP level of theory. Further, the reactivity descriptors have been calculated using B3LYP/6-31G(d,p) basis.
Geometry optimization and energies
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4.1.
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4. Results and discussions
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Starting from the molecular conformation of CAD in the asymmetric unit of the crystalline structure [3], the geometry optimization was performed as the first task without
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any constraints to the potential energy surface. The optimized structural parameters, using energy minimization, were used in vibrational frequency calculation to characterize all
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stationary points as minima. The ground state optimized structure of the molecule is presented in Fig. 1(b). The optimized structure is remarkably similar to the experimental one
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[3]. Both the optimized and experimental molecular conformations were compared by
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superimposing them using a least-square algorithm that minimizes the distance between the corresponding non-hydrogen atoms, as shown in Fig. S1 (Supplementary material). For
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clarity, all the hydrogen atoms are removed. The good agreement between the optimized and the experimental structure show that the optimized structure makes a replica of the
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experimentally observed conformation. The relative energies of the molecule are calculated employing ab initio HF and DFT functional. The energy calculated by DFT (-709572.532 kcal/mol) is lower, showing more stability, than the one calculated by HF (-705094.857 kcal/mol). The enthalpy difference between these two theories is 17.586 kcal/mol. A comparison of the optimized values of structural parameters (bond length, bond angle and torsion angle) with the observed values is given in Table S1 (Supplementary material). In general, the bond lengths do not differ by
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ACCEPTED MANUSCRIPT more than 0.02 Å, except the bonds O1-C18 and O3-C9, which differ by 0.06/0.07 and 0.015/0.03 Å in the DFT/HF, respectively. The bond angles do not differ by more than 3o, except the angles C9-O3-C19 and C6-N1-C15, which differ by 4.4/4.6o and 2.9/3.3o in the DFT/HF. Similarly, the dihedral angles do not differ by more than 10o, except the angles C20-O4-C10-C9, C20-O4-C10-C11, and C7-N1-C15-C14, which differ by 13.8/12.2o,
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4.2. Molecular Electrostatic Potential (MEP) Surface
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14.7/12.4o and 9.8/10.4o in the DFT/HF, respectively.
The MEP provides a visual method to understand the sites of the relative charge
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distribution in a molecule [12, 24]. In the generated surface, negative electrostatic potential colored in shades red, whereas, positive one colored in the shades of blue. A molecule shows
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its non-polar behavior if the surface is largely white or lighter color shades. Potential increases in the order red < orange < yellow < green < blue. The MEP of CAD mapped using
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the DFT/6-311++G (d,p) output is shown in the Fig. 2. The highest negative potential with
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red blobs is visible over the regions near nitrogen in ring and oxygen atoms of methoxy groups. The yellowish blob reflects less negative potential, is visible over the oxygen atoms
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of ring R1. A positive charge is localized near the hydrogen atoms of the methyl group. The
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value of Mulliken charges is presented in the Table S2 (Supplementary material).
4.3. Natural bond orbital (NBO) analysis NBO analysis is one of the efficient method for studying hybridization, conjugative interactions, covalence effects and charge transfer in polyatomic wave functions [11, 12]. The information from the first-order density matrix of the ab initio calculations develops a unique set of atomic hybrids and bond orbitals, which leads to “Lewis structure”. It helps in the investigation of intra- and intermolecular interactions among bonds. In the present work,
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ACCEPTED MANUSCRIPT utilizing the second-order micro-disturbance theory analysis, we have accounted some of the electron acceptors, donor orbitals and the interacting stabilization energy, E(2). The hyperconjugative interaction energy was deduced from the second-order perturbation approach [33-35]. The most important interaction between ‘‘filled’’ (donor) Lewis type NBOs and ‘‘empty’’ (acceptor) non-Lewis NBOs are reported in Table 1.
*C10-C11 bond of ring R5 which increase the ED (0.409e) leading to the
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C8-C9 to
electrons from C12-C13 and
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There occurs a strong hyperconjugative interaction of
NBO further conjugates with
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stabilization energy of 19.44 and 21.31 kcal/mol, respectively. This enhanced
*C10-C11
*C8-C9 resulting to high stabilization of 228.59 kcal/mol.
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Another hyperconjugative interactions were observed from
C4-C16 and
C17-C18 to
*C2-C3 bond of ring R2, and from C8-C9 and C10-C11 to *C12-C13 of ring R5 which
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increase the EDs of 0.366e and 0.363e, respectively. Similarly, the enhanced / *C2-C3 NBOs further conjugate to
*C17-C18
*C4-C16 leading to stabilization of 137.61/141.91
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kcal/mol, respectively. The interactions related to the resonance in the molecule, are electron
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donation from LP(2)O1/LP(2)O2 to antibond acceptors
*C17-C18 / *C2-C3 of ring R2
(24.98 /25.28 kcal/mol), and from LP(2)O4 to the antibond acceptor *C10-C11 of ring R5
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(27.78 kcal/mol). The interactions are confined between those atoms which are attached with the rings. A comparison of Mulliken and NBO charges is presented in the Table S2
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(Supplementary material).
Selected Lewis (bond or lone pair) NBO orbitals of investigated molecule with their valence hybrids corresponding to the various interactions are listed in Table S3 (Supplementary material). The valence hybrids analyses of NBO orbitals show that all the C– N bond orbitals are polarized towards the nitrogen atom (60.95 - 61.60% at N), whereas the C–O bond orbitals are polarized towards the oxygen atom (67.04 - 68.48% at O). Therefore, they consist with the maximum electron density on the nitrogen and oxygen atoms. The 8
ACCEPTED MANUSCRIPT electron density distribution around the imino group also influences the polarity of the compound.
4.4. Chemical reactivity
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4.41. Global reactivity descriptor
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Electrophilicity and hardness are two important molecular properties, which are
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useful for interpreting and understanding the stability and reactivity of molecular system [21]. According to the Hohenberg and Kohn (HK) theorems [17], the energy of the basic state of
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an electronic system is a functional of electron density. On the basis of Koopman’s theorem [21], global reactivity descriptors; electronegativity (χ), chemical potential (σ), global
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hardness (η), global softness (S) and global electrophilicity index (ω) were calculated using the energies of frontier molecular orbitals EHOMO, ELUMO and given by relations:
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χ = - ½[EHOMO + ELUMO]
η = ½[EHOMO + ELUMO]
ω = σ2/2η
………….. (4) …………… (5) ……………… (6)
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∆Nmax = - σ/η
………….. (3)
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S = ½(η)
……….. (2)
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σ = - χ = ½[EHOMO + ELUMO]
…….…….. (1)
According to Parr et al. 1999 [36] ω, a positive and finite quantity is a global reactivity index similar to
(a measure of the resistance of a system to transfer charge), and
σ. The direction of the charge transfer is completely determined by the electronic chemical
potential of the molecule because an electrophile is a chemical species capable of accepting electrons from the environments. Therefore, its energy must decrease upon accepting the electronic charge and electronic chemical potential must be negative. The values of frontier
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ACCEPTED MANUSCRIPT energy levels (EHOMO, ELUMO), energy band gap (ΔE), χ, σ, η, S, ω, and additional ΔN for CAD are listed in the Table S4 (Supplementary material). The calculated high value of the electrofilicity index (ω) shows that the molecule behaves as a strong electrophile.
4.42. Local Reactivity Descriptors
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Using Hirschfield population analysis of neutral, cation and anion state of molecule,
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Fukui functions (fk+, fk-, fk0) [36-39], are calculated at same calculation method B3LYP/6-21 G(d,p) using following relations: fk+ = [q(N+1) - q(N)] for nucleophilic attack
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……………….. (7)
fk- = [q(N) - q(N-1)] for electrophilic attack
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fk0 = ½[q(N+1) - q(N-1)] for radical attack
………………… (8) ………………. (9)
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where N, N-1 and N+1 are total electrons present in neutral, cation and anion state of molecule, respectively.
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Local softness (sk+, sk-, sk0) and local electrophilicity indices (ωk+, ωk-, ωk0), also used
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to describe the reactivity of atoms in the molecule, are calculated using the following equations:
sk+ = S fk+, sk- = S fk-, sk0 = S fk0
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………………… (10)
ωk+ = ω fk+, ωk- = ω fk-, ωk0= ω fk0
……………….. (11)
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where +, −, 0 signs show nucleophilic, electrophilic and radical attack, respectively. The calculated values of Fukui functions, electrophilicity descriptors, and the nucleophilicity descriptors are listed in the Table 2. The high value of fk- at O2 and O1 atoms indicate that these sites are more prone to nucleophilic attack. Similarly, the sites at C1, C12, and C20 are more prone to electrophilic attack due to having maximum value of fk+.
4.5. UV spectroscopy and HOMO-LUMO analysis
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ACCEPTED MANUSCRIPT The UV-Vis absorption spectrum of CAD is shown in the Fig. 3 with the absorption bands at 294 and 286 nm in EtOH solvent. Both the frontier molecular orbitals (FMOs), highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) are the most important orbitals participated in a chemical reaction. The transition of an electron between HOMO and LUMO is a principal factor that determines the easiness of
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chemical reaction and its path, irrespective to the intra- and intermolecular processes. Higher
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the gap between these two bands ( E) more is the stability of the system and vice versa.
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Here, we have demonstrated the molecular orbital both in the gas and solvent phases as an example to compare the effect of the solution on absorptions. The energy gap in gas phase as
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well as in the solvent phase is 5.508 eV and 5.411 eV, respectively. The calculated wavelengths (λmax), vertical excitation energies, oscillator strengths (f),
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dipole moments (μ), and excitation transition with spectral assignments for vacuum and the solvent environment are carried out as given in Table 3. The transition observed in the UV
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spectrum is π π*. In the gaseous phase in the LUMO, the charge is mainly accumulated on
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the ring R2 portions. Similarly, in HOMO and HOMO-1 the charge density is over the rings R2 and R3. However, in LUMO+1 it is over the ring R5 portion as shown in Fig. S2
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(Supplementary material). In solvent phase, the allowed dipole transition is at 261.32 nm (H
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L) with oscillator strength of 0.1363 and, in the gaseous phase, it is at 257.51 nm (H with oscillator strength of 0.0141. The H-1
L)
L transition is predicted at 252.05 nm with the
oscillator strength 0.0811 in the gas phase, while, H-1
L+1 transition at 290.14 nm is
predicted with oscillator strength 0.0240 in the solvent phase, respectively. The charge accumulation within the molecule in solvent phase is given in the Fig. S3 (Supplementary material).
4.6.
Vibrational spectrum 11
ACCEPTED MANUSCRIPT This CAD molecule has 46 atoms and hence gives 132 (3N-6; N the number of atoms) modes of vibrations. All the wavenumbers are both IR and Raman active. We have calculated these fundamental wavenumbers, their intensities and PED along with the internal coordinates obtained by HF and DFT with 6-311++G(d,p) basis set calculations. The wavenumbers predicted by HF method are larger than B3LPY due to the inclusion of electron
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correlation in the later. Since, the vibrational wavenumbers obtained from the DFT
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calculations are higher than the experimental wavenumbers, so the vibrational wavenumbers obtained from the DFT calculations were corrected by the wavenumber linear scaling (WLS)
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of Yoshida et.al. [40] by using the expression: υobs = (1.0087-0.0000163 υcal) υcal.
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The Raman scattering cross-sections, ∂σj/∂Ω, which is proportional to the Raman intensities may be calculated from the Raman scattering amplitude and predicted
h 8 2 c j
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24 4 45
4 0 j hc j 1 exp kT
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j
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wavenumbers for each normal modes using the relationship [41-43]:
Sj
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where, sj and υj are the scattering activities and the predicted wavenumbers (in cm-1), respectively of the jth normal mode, υo is the Raman exciting wavenumber (cm-1), and h, c
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and k are the universal constants. A comparison of the wavenumbers calculated by the DFT method shows very good agreement with the experimental values due to incorporation of electron correlation. The simulated and observed IR and Raman modes of the CAD molecule are given in Figs. 4 and 5, respectively. Out of several internal coordinates that may be present in the PED as given in Table 4, we have discussed here only some prominent modes:
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ACCEPTED MANUSCRIPT 4.6.1. Methoxy group vibration In a molecule containing methoxy group, the electronic charge is back donated from the lone pair atoms (oxygen) to the
* orbital of CH bond weakens the CH bonds. This
increases the CH bond resulting in the enhancement of the IR intensities in CH stretching [44, 45]. CH3 group has several modes associated with it, such as symmetric and asymmetric
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stretches, bends, rocks and torsions. There are two methyl groups (Me1 and Me2) connected to
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the same ring R5 as shown in the Fig. 1(b), forming methoxy groups. Asymmetric stretching
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modes associated to each Me1 and Me2 groups predicted in the range of 3000-2935 cm-1, were assigned in the weak IR and the strong Raman peaks. Symmetric stretching modes were
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predicted at 2902 and 2893 cm-1. Asymmetric deformations of Me1 and Me2 were assigned at 1493/1468 and 1485/1474cm-1 in the IR, and at 1491/1466 and 1480/1470 cm-1 in the Raman
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spectra, that is calculated at 1503/1473 and 1495/1481 cm-1, respectively. The calculated rocking vibrations at 1196/1166 cm-1 are in good agreements with 1186/1163 cm-1 in the IR
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and 1189/1164 cm-1 in the Raman peaks.
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.
4.6.2. Ring R1 vibrations
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Basically, six fundamental vibrational assignments can be associated with each CH2 moiety namely; symmetric and asymmetric stretch, deformation and rocking modes which
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belong to the polarized in-plane vibration. In addition to that, CH2 wagging and twisting would be expected to be depolarized out-of-plane symmetry [46]. The asymmetric stretching vibration of CH2 calculated at 2978 cm-1 and observed at 2997/3000 cm-1 in the IR/Raman spectrum. The symmetric stretching was observed at 2872/2868 cm-1 in the IR/Raman spectrum and calculated at 2886 cm-1 as shown in Table 4. Deformation mode of vibration predicted at 1537 cm-1 is in good agreement with the observed IR/Raman band at 1531/1533 cm-1. Highly mixed CH2 wagging, twisting and rocking vibrations were predicted at 1419,
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ACCEPTED MANUSCRIPT 1206 and 1138 cm-1, respectively.
4.6.3. Ring R2 vibrations The carbon-hydrogen stretching vibrations give rise to the weak bands in the region 3100-3000 cm−1 in all the aromatic compounds [47]. In the present case, the CH stretching
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modes were observed in this range with 100% contributions in PED. These bands are weak in
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the IR and medium strong in the Raman spectra. The in-plane deformation observed as the weak IR peak at 1495 cm-1 and the strong Raman peak at 1493 cm-1 and predicted at 1511
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cm-1. The out-of-plane deformations were calculated below 875 cm-1.
4.6.4. Ring R3 vibrations
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The CH stretching vibration predicted at 2766 cm-1 was assigned to IR/Raman peak at 2750/2753 cm-1. The rocking mode was observed at 1339/1345 cm-1 in the IR/Raman spectra.
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The mixed NC stretching vibrations were predicted at 1184 and 1159 cm-1 in the scaled DFT.
4.6.5. Ring R4 vibrations
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The CH2 asymmetric stretching vibrations predicted at 2958/2949 cm-1 were assigned to the strong Raman peaks at 2946/2940 cm-1 and the weak IR peaks at 2939/2937 cm-1. The
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calculated symmetric stretching vibrations for these modes are 2914 and 2784 cm-1. Their deformation, wagging, twisting and rocking vibrations are predicted at 1480/1472, 1377/1363, 1311/1274 and 1025 cm-1, respectively. The ring CC stretching vibration predicted at 1145 cm-1 is in good agreement with the observed IR/Raman peak at 1142/1140 cm-1.
4.6.6. Ring R5 vibrations
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ACCEPTED MANUSCRIPT The CH stretching vibrations associated with this ring were predicted at 3079 and 3040 cm-1. The CH in-plane bending was calculated at 1234 cm-1 corresponding to the observed peak at 1227 and 1233 cm-1 in the IR and Raman spectra, respectively. The out-ofplane deformation vibration of this mode was predicted at 924 and 803 cm-1. The calculated trigonal ring deformation mixed with the CO stretching vibration at 1248 cm-1 was found to
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be consistent with the recorded values at 1248/1241 cm-1 in the IR/Raman spectra. Another
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CO stretching mode vibration was predicted at 1293 cm-1. The CO in-plane deformation
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calculated at 651 cm-1 was assigned at 654/ 651 cm-1 in the IR/Raman spectra.
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4.7. Nonlinear optical (NLO) properties
Nonlinear optics deals with the interactions of various materials in applied
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electromagnetic fields to generate new field altered in phase, frequency, amplitude or other physical properties [48]. Some organic substances with
electronic system exhibit the largest
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known nonlinear coefficients and show promise for thin fabrication, allowing the enormous
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function and cost integrated electronic circuitry. The total dipole moment (μo), mean polarizability (∆α), the anisotropy of the
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polarizability (| |) and the total first hyperpolarizability (βo) using x, y, z components [39, 49] are calculated from the Gaussian 09 output and listed in the Table S5 (Supplementary
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material). In this study, the calculated values of μo , |
| and βo are 1.92 Debye, 32.76 x10-24
esu and 1200.87 x10-33 esu, respectively which are higher than those of urea (μo = 1.528 Debye, βo = 343.27 x 10-33 esu.) [50, 51]. These values are very much comparable with brucine/ strychnine (3.18/3.30 Debye, 39.47 x10-23/33.63 x10-23 esu and 221.97 x10-34/111.58 x10-34 esu) [13] and the p-NA [52]. From the above results, it appears that the title compound can be used as a good nonlinear material for the optical devices.
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ACCEPTED MANUSCRIPT 5. Conclusion Present work is mainly concentrated on the study of the wavenumber assignments of CAD by using IR and Raman data together with the quantum chemical calculations. Both the IR and Raman spectra were in good agreements with the modes calculated by the DFT. A comparison of the scaled wavenumbers obtained using DFT methods have better accuracy
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with the experimental modes than HF due to the fact that the former includes some of the
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electron correlation effects. The observed electronic spectra have some higher values (294
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and 286 nm) compared with the theoretical absorption data (258 and 252 nm) and the molecular orbital coefficient analysis suggests that the electronic transitions are assigned to π*. NBO analysis shows the stability and charge delocalization from various bonding to
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π
anti-bonding orbitals ( *) of the title compound. MEP studies suggest that the nitrogen and
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oxygen (of the methoxy groups) atoms are the most reactive sites. The reactivity descriptors also tell that O2 and O1 atoms are more prone to nucleophilic attack. The observed
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microscopic NLO properties suggest its potential use in the development of NLO materials. It
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is reported that the title compound possesses anti-fibrillatory and antioxidant activity as well as behaves as a potent inhibitor of platelet aggregation. To predict and confirm these types of
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activity theoretically, molecular docking studies will be performed which are very useful for
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the industrial and biologically active compounds.
Acknowledgments:
B.D. Joshi would like to thank the CNPq-TWAS for fellowship (CNPq-TWAS/PostDoc/2014/ FR number: 3240279899) to pursue Post-Doc study in UFC, Fortaleza, Brazil. A.S. thanks University Grants Commission (UGC), New Delhi for financial assistance under PDF for Women Scientist; grant no. F.15-1/2014-15/PDFWM-2014-15-GE-UTT-24257 (SAII). P.T. is thankful to DST, New Delhi for financial support under the Indo- Brasil project
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ACCEPTED MANUSCRIPT (grant no. DST/INT/Brazil/P-10/2013).
References [1] S. Mills, K. Bone, Principles, and Practice of Phytotherapy, Churchill Livingstone: Philadelphia, 2000.
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[2] S. Foster, J. Duke, A Field Guide to Medicinal Plants and Herbs of Eastern and Central
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[4] A.Y. Sun, D.X. Li, Acta Pharmacol. Sinica. 14 (1993) 301-303. [5] B. Xuan, W. Wang, D.X. Li, Acta Pharmacol. Sinica. 15 (1994) 133-135.
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G. Scalmani, V. Barone, B. Mennucci, G.A. Petersson, H. Nakatsuji, M. Caricato, X. Li, H.P. Hratchian, A.F. Izmzylov, J. Bloino, G. Zheng, J.L. Sonnenberg, M. Hada,
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M. Ehara, K. Toyota, R. Fukuda, J. Ishida, M. Hasegawa, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven, J.A. Montgomery, Jr., J.E. Peralta, F. Ogliaro, M.
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Normand, A. Raghavachari, A. Rendell, J.C. Burant, S.S. Iyengar, J. Tomasi, M.Cossi, N. Rega, J.M. M illan, M. Klene, J.E. Knox, J.B. Cross, V. Bakken, C.
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G.A. Voth, P. Salvador, J.J. Dannerberg, S. Dapprich, A.D. Daniels, J. Farkas, B. Foresman, J.V. Ortiz, J. Cioslowski, and D.J. Fox, GAUSSIAN 09, Revision, Gaussian, Inc., Wallingford CT, USA, 2009. [19] C. Lee, W. Yang, R.G. Parr, Phys. Rev. 37 (1988) 785-789. [20] A.D. Becke, J. Chem. Phys. 98 (1993) 5648-5652. [21] R.G. Parr, W. Yang, Density Functional Theory of Atoms and Molecules, Oxford, New York, 1989.
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ACCEPTED MANUSCRIPT [22] E.D. Glendering, A.E. Reed, J.E. Carpenter, F. Weinhold, NBO Version 3.1, TCI, University of Wisconsin, Madison, 1998. [23] G.A. Petersson, A. Bennett, T.G. Tensfeldt, M.A. Allaham, W.A. Shirley, J. Mantzaris, J. Chem. Phys. 89 (1988) 2193-2218. [24] G.A. Petersson, M.A. Allaham, J. Chem. Phys. 94 (1991) 6081-6090.
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[27] G. Fogarasi, X. Zhou, P.W. Taylor, P. Pulay, J. Am. Chem. Soc. 114 (1992) 81918201.
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[28] A. Frisch, A.B. Nielson, A.J. Holder, Gauss View User Manual, Gaussian Inc, Pittsburgh, P.A., 2000.
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[29] G.A. Zhurko, D.A. Zhurko, Chemcraft 2005,. [30] S. Miertuš, E. Scrocc, J. Tomasi, Chem. Phys. 55 (1981) 117-129.
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[34] A.P. Scott, L. Radom, J. Phys. Chem. 100 (1996) 16502-16513. [35] F. Weinhold, C.R. Landis, Valency, and bonding: A Natural Bond Orbital Donor-
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Acceptor Perspective, Cambridge University Press, New York, 2005. [36] R.G. Parr, L. Szentpály, S. Liu, J. Am. Chem., Soc. 121 (1999) 1922-1924. [37] R.G. Parr, R.G. Pearson, J. Am. Chem. Soc., 105 (1983) 7512-7516. [38] P. Geerlings, F. De Proft, W. Langenaeker, Chem. Rev., 103 (2003) 1793-1874. [39] P.K. Chattaraj, S. Giri, J. Phys. Chem. A, 111 (2007) 11116-11121. [40] H. Yoshida, K. Takeda, J. Okamura, A. Ehara, H. Matsurra, J. Phys. Chem. A 106 (2002) 3580-3586.
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ACCEPTED MANUSCRIPT [41] P. Pulay, G. Fogarasi, G. Pongor, J.E. Boggs, A. Vargha, J. Am. Chem. Soc., 105 (1983) 7037-7047. [42] G.A. Guirgis, P. Klaboe, S. Shen, D.L. Powell, A. Gruodis, V. Aleksa, C.J. Nielsen, J. Tao, C. Zheng, J.R. Durig, J. Raman Spectrosc. 34 (2003) 322-336. [43] P.L. Polavarapu, J. Phys. Chem. 94 (1990) 8106-8112.
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sixth ed., John Wiley & Sons Inc., New York, 2003.
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[44] R.M. Silverstein, F.X. Webster, Spectroscopic Identification of Organic Compounds,
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[45] P. Agarwal, N. Choudhary, A. Gupta, P. Tandon, Vibrational Spectrosc. 64 (2013) 134-147.
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[46] B.D. Joshi, A. Srivastava, P. Tandona, S. Jain, Spectrochim. Acta A 82 (2011) 270278.
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[47] B. Smith, Infrared Spectral Interpretation. A Systematic Approach, CRC Press, Washington, DC, 1999.
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[48] D.J. Williams, Angew. Chem. Int. Ed. Engl. 23 (1984) 690-703.
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[49] H. Alyar, Z. Kantarci, M. Bahat, E. Kasap, J. Mol. Struct. 834-836 (2007) 516-520. [50] N. Sundaraganesan, J. Karpagam, S. Sebastian, J.P. Cornard, Spectrochim. Acta A 73
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[52] L. Jensen, P.D. Thvan, J. Chem. Phys., 123 (2005) 074307-7.
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ACCEPTED MANUSCRIPT Figure captions Fig. 1(a). Chemical structure of CAD. Fig. 1(b). Optimized structure of CAD. Fig. 2. MEP mapped (from -4.389e-2 to +4.389e-2). Fig. 3. UV-Vis spectra taken in ethanol.
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Fig. 4. Comparison between observed and the calculated FT-IR spectra.
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Fig. 5. Comparison between observed and the calculated FT-Raman spectra.
Fig. S2. HOMO-LUMO plot in the gas phase.
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Fig. S3. HOMO-LUMO plot in the solvent phase.
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Fig. S1. Overlapping between experimental (purple) and the optimized molecular structures.
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Fig. 1
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Fig. 2
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Fig. 3
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Fig. 4
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Fig. 5
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ACCEPTED MANUSCRIPT Table 1 Second Order Perturbation Theory Analysis of Fock Matrix.
LP(2)O1
Acceptor NBO(j)
1.86493
1.86334
E(2)a kcal/mol
ED/e
[E(j)-E(i)]b
[Fi,j]c
au
au
*C17 – C18
0.36546
24.98
0.36
0.090
*C1 – H1
0.03904
6.29
0.68
0.060
*C2 – C3
0.36557
25.28
0.36
0.090
*C1 – H2
0.03904
6.26
0.68
0.060
0.39
0.056
1.90851
*C8 – C9
0.37837
8.71
LP(2)O4
1.85085
*C10 – C11
0.40903
27.78
0.34
0.094
*C20 – H19
0.01957
5.75
0.69
0.058
*C6 – H6
0.03722
8.51
0.65
0.068
*C7 – H8
0.03865
0.65
0.067
0.02870
6.17
1.01
0.071
0.02884
6.37
1.01
0.072
1.87519
1.9644
*O1 – C18
C3 – C4
1.96576
*O2 – C2
C17 – C18
1.97090
*C2 – C18
0.03844
5.15
1.29
0.073
C2 – C18
1.97304
*C2 – C3
0.36557
5.08
1.29
0.072
C4 – C16
1.69172
*C17– C18
0.36546
18.46
0.27
0.064
*C2 – C3
0.36557
18.09
0.27
0.064
* C8 – C9
0.37837
21.56
0.28
0.07
*C10 – C11
0.40903
19.44
0.27
0.066
*C12 – C13
0.36307
19.33
0.30
0.068
*C10 – C11
0.40903
21.31
0.28
0.070
*C4 – C16
0.34877
17.72
0.32
0.068
*C2 – C3
0.36557
19.59
0.30
0.070
*C4 – C16
0.34877
18.38
0.32
0.069
*C17– C18
0.36546
19.56
0.30
0.069
*C12 – C13
0.36307
19.48
0.31
0.070
*C8 – C9
0.37837
17.13
0.30
0.065
*C4 – C16
0.34877
137.61
0.02
0.080
C17 – C18
C2 – C3
C10 – C11
*C17– C18
D
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C8 – C9
1.67477
1.67004
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C12 – C13
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8.39
C16 – C17
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LP(1)N1
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LP(2)O3
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LP(2)O2
ED/e
PT
Donor NBO(i)
1.71465
1.71267
1.68223
0.36546
27
ACCEPTED MANUSCRIPT *C2 – C3
0.36557
*C4 – C16
0.34877
141.91
0.02
0.08
*C10 – C11
0.40903
*C12 – C13
0.36307
159.12
0.02
0.081
*C8 – C9
0.37837
228.59
0.01
0.082
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Energy E(2) ≥ 5 kcal mol-1 is assigned. a (2) E means energy of hyper conjugative interaction (stabilization energy). b Energy difference between donor and acceptor i and j NBO orbitals. c F(i, j) is the Fock matrix element between i and j NBO orbitals
28
ACCEPTED MANUSCRIPT Table 2 Atomic charges (in esu), Fukui functions (f+k,f--k); Local softness (s+k,s-k)); and local electrophilicity indices (ω+k, ω-k)); in eV for atomic sites, using Hirshfeld population analysis at B3LYP/6-31G(d,p) level. Fukui functions
Local softness
Local electrophilicity indices
qN-1
f+k
f--k
s+k
s-k
ω+k
ω -k
1 O
-0.165488
-0.122057
-0.180717
0.043431
0.015229
0.059801
0.020969
0.058922
0.020661
2 O
-0.164636
-0.114692
-0.185035
0.049944
0.020399
0.068769
0.028088
0.067759
0.027675
3 O
-0.169553
-0.144161
-0.176066
0.025392
0.006513
0.034963
0.008968
0.034449
0.008836
4 O
-0.148781
-0.107017
-0.150034
0.041764
0.001253
0.057506
0.001725
0.056661
0.001700
1 N
-0.120830
-0.083205
-0.121785
0.037625
0.000955
0.051807
0.001315
0.051046
0.001296
1 C
0.233609
0.302269
0.167463
0.068660
0.066146
0.094539
0.091078
0.093150
0.089740
2 C
0.052989
0.092700
0.009552
0.039711
0.043437
0.054679
0.059809
0.053876
0.058931
3C
-0.008032
0.038037
-0.116305
0.046069
0.108273
0.063433
0.149083
0.062501
0.146893
4 C
-0.015226
0.019149
-0.033162
0.034375
0.017936
0.047332
0.024696
0.046636
0.024334
5 C
0.018291
0.063392
-0.022792
0.045101
0.041083
0.062100
0.056568
0.061188
0.055737
6 C
0.052459
0.097040
0.010711
0.044581
0.041748
0.061384
0.057484
0.060483
0.056639
7 C
0.059514
0.100245
0.003940
0.040731
0.055574
0.056083
0.076521
0.055259
0.075397
8 C
-0.020745
-0.013799
-0.045168
0.006946
0.024423
0.009564
0.033628
0.009424
0.033134
9 C
0.052690
0.089556
0.005925
0.036866
0.046765
0.050761
0.064392
0.050016
0.063446
10 C
0.059311
0.096577
0.035486
0.037266
0.023825
0.051312
0.032805
0.050558
0.032323
11 C
-0.034798
0.007966
-0.105321
0.042764
0.070523
0.058882
0.097104
0.058018
0.095678
12 C
-0.014170
0.044029
-0.106163
0.058199
0.091993
0.080135
0.126667
0.078958
0.124806
13 C
-0.020859
0.004017
-0.032678
0.024876
0.011819
0.034252
0.016274
0.033749
0.016035
14 C
0.016552
0.057367
-0.018815
0.040815
0.035367
0.056199
0.048697
0.055373
0.047982
15 C
0.048796
0.089400
0.024872
0.040604
0.023924
0.055908
0.032941
0.055087
0.032457
16 C
-0.017853
0.011469
-0.040174
0.029322
0.022321
0.040374
0.030734
0.039781
0.030283
17 C
-0.007228
0.023172
-0.105810
0.0304
0.098582
0.041858
0.135739
0.041243
0.133745
18 C
0.052136
0.084925
0.019574
0.032789
0.032562
0.045148
0.044835
0.044485
0.044177
19 C
0.118028
0.162462
0.051688
0.044434
0.06634
0.061182
0.091345
0.060283
0.090003
20 C
0.143607
0.200949
0.088600
0.057342
0.055007
0.078955
0.075740
0.077795
0.074628
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qN
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Hirshfeld atomic charges
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Atom no.
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ACCEPTED MANUSCRIPT Table 3 Electronic transitions, absorption wavelength λmax (nm), excitation energy (eV), oscillator strengths (f), frontier orbital energies (eV) and dipole moment (Debye). λmax
Excitation transition Solvent phase
H-1
3
H
L+1
H
4
H
L+2
5
H
L+3
6
H-1
L+2
H-1
7
H-1
L+3
8
H-2
L+3
Solvent phase
Gas phase
Solvent phase
Gas
Solvent
0.0141
0.1367
L
294
257.51
261.32
4.8148
4.7446
L+1
286
252.05
250.14
4.9191
4.9566
0.0811
0.0240
L+1
247.52
245.76
5.0091
5.0450
0.0118
0.0104
H
L+2
235.08
234.16
5.2740
0.0525
0.0369
H
L+3
228.96
230.84
L+2
219.71
222.06
H-1
L+3
216.06
218.62
H-4
L+1
210.84
200.35
H
L
Gas phase
H-1
ELUMO
Gas
-5.487369
Solvent
-5.534935
5.2949
5.4150
5.3709
0.0352
0.0964
5.6431
5.5833
0.0507
0.0495
5.7384
5.6712
0.0182
0.0229
5.8806
6.1884
0.0536
0.0967
E
µ (D)
0.020300
5.507669
1.8635
-0.124057
5.410878
2.0921
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EHOMO
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2
L
Calculated
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H
Calculated
Oscillatory strength (f) Calculated
SC
1
Expt
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Gas phase
E (eV)
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Excited states
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Transition type/ assignments
π
π*
ACCEPTED MANUSCRIPT Table 4 Comparison between calculated and observed (FT-IR and micro-Raman) wavenumbers (cm-1) and the PED distribution of CAD. Calculated Unscaled
Observed Scaled
IR
Potential energy distribution (PED %)
Raman
HF
DFT
HF
3220
3367
3079
3212
3065
3069
R5[υ(CH)](99)
3216
3359
3075
3204
3038
3067
R2[υ(CH)](98)
3206
3344
3067
3191
3036
3038
R2[υ(CH)](98)
3177
3316
3040
3166
-
3025
R5[υ(CH)](99)
3148
3299
3014
3151
3001
3003
Me2[υa(CH3)](100)
3145
3279
3011
3133
2999
3002
Me1[υa(CH3)](99)
3109
3278
2978
3132
2997
3000
R1[υa(CH2)](99)
3098
3246
2969
3102
-
-
3086
3237
2958
3094
2939
2946
3077
3225
2949
3083
2937
3075
3222
2948
3081
2930
3074
3209
2947
3069
3069
3202
2942
3038
3189
2914
3032
3178
2908
3025
3166
2902
3015
3166
2893
3008
3162
2918
NU
SC
RI
PT
DFT
Me1[υa(CH3)](99)
3938
Me2[υa(CH3)](100)
2928
2930
R3[υa(CH2)](93)
3063
2926
2928
R3[υa(CH2)](98)
3051
2899
2897
R4[υs(CH2)](99)
3041
2897
2895
R3[υs(CH2)](97)
3030
2887
-
Me1[υs(CH3)](99)
3030
2885
2878
Me2[υs(CH3)](99)
2886
3027
2872
2868
R1[υs(CH2)](99)
3078
2805
2950
-
2805
R3[υs(CH2)](95)
2895
3068
2784
2942
2752
2755
R4[υs(CH2)](95)
2875
3046
2766
2921
2750
2753
R3[υ(CH)](94)+υa(CH2)(5)]
1677
1822
1646
1783
1622
1626
R2[υ(CC)(57)+δa(11)+δin(CH](5)]+R1[δring](8)
1674
1806
1642
1768
1618
1625
R2[υ(CC)(52)+[δ’a](11) +R1[υ(CC)](23)
1660
1798
1629
1760
1605
1607
R5[υ(CC)(51) +δa(11)+δin(CH)(8)]
1632
1769
1603
1733
1584
1586
R5[υ(CC)(51)+δ’a(10)+δin(CH)(6)]+R4[υ(CC)]
PT E
D
R4[υa(CH2)](99)
AC
2940
CE
MA
R4[υa(CH2)](96)
32
ACCEPTED MANUSCRIPT (21) 1680
1537
1649
1531
1533
R1[δ(CH2)](84)
1538
1662
1513
1631
1506
1501
R5[υ(CC)(32)+δin(CH)(26)]+R4[υ(CC)](15)+δa [Me2(CH3)](8)
1536
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1511
1625
1495
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R2[δin(CH)(29)+υ(CC)](24)]+R1[υ(CC)(19)+δ CH2](12)+υ(CO)(5)]
1527
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1503
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1493
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Me1(CH3)[(δa(56)+δ’(32)+ρ’(9)]
1522
1634
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R3[δ(CH2)](67)+R4[δ(CH2)](13)+δ[Me2(CH3)] (5)
1519
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Me2(CH3)[δa(77)+ρ’(8)]+R3[δ(CH2)](6)
1505
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Me2(CH3)[δ’a(88)+ρ(5)]
1504
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R4[δ(CH2)](23)+δa[Me1(CH3)](21)+R3[δ(CH2) ](12)+R5[υ(CC)](8)+R5[υ(CO)](6)
1497
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Me1(CH3)[ δ’a(55)+δa(33)+ρ(7)]
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R4[δ(CH2)](48)+δs[Me1(CH3)](20)+δs[Me2(CH 3)](6)+R3[δ(CH2)](5) R3[δ(CH2)](88)
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δs[Me2(CH3)](66)+R4[δ(CH2)](15)
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R4[δ(CH2)](68)+δs[Me2(CH3)](10)+δs[Me1(CH 3)](7)
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R2[υ(CC)](22)+R3[υ(CC)(10)+δtrig(5)+δa(5)]+ R4[δ(CH2)](6)+R1[ω(CH2)](6)
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δs[Me1(CH3)](34)+R5[υ(CC)](18)+R4[υ(CC)]( 6)
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R1[ω(CH2)](42)+R3[ω(CH2)](20)+R4[ω(CH2)] (8)
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R1[ω(CH2)](36)+R3[ω(CH2)](24)+R4[ω(CH2)] (8)
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R2[υ(CC)](56)+R1[υ(CO)](5)
1396
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1377
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R4[ω(CH2)](31)+R3[CH(ρ’)(CH(20)+ω(CH2)( 8)]
1383
1497
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R4[ω(CH2)](35)+υ(CC)(13)]+R3[ρ(CH)(13)+ω (CH2)](11)]
1371
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R3[(ω(40)+γ(10))CH2+υ(CC)(13)]
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R3[ρ(CH)(40)+(ω(CH2)(19)+γ(CH2)(5)]
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R5[υ(CC)](50)+R3[ρ’(CH)](9)+R4[υ(CC)](7)
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R4[γ(24)+(5)](CH2)+R3[ρ’(CH)](17)+υ(N5C3 3)(5)+γ(CH2)(5)]+R5[υ(CC)](8)+δin(CH)(5)]
1317
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R4[υ(CC)](16)+υ(NC)(6)]+R5[υ(CC)](16)+R3[ γ(CH2)](14)
1310
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R5[υ(CO)(28)+δin(CH)(13)+υ(CC)(10)+R4[ω( CH2)](6)+R3[γ(CH2)](5)
1290
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R4[γ(CH2)](22)+R1[υ(CO)](11)+υ(CC)(9)]+R2 [υ(CC)(19)]+R3[γ(CH2)](7)
1270
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R2[δin(CH)](27)+R3[γ(CH2)(10)+δtrig(9)]+R4[γ (CH2)(10)+υ(NC)(5)]
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R5[δtrig(24)+υ(CO)(23)]+R4[ω(CH2)(8)+υ(CC) ](7)
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R4[γ(CH2)](25)+R2[υ(CC)(22)+δin(CH)(6)]+R 1[υ(CC)(7)+υ(CO)(9)]
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R1[γ(CH2)](32)+R4[γ(CH2)(21)+R2[δin(CH)(7) ]+R2[δin(CH)](6)
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ρ’[Me2(CH3)](29)+R5[δin(CH)(15)+δtrig(7)]+υ( CC)(6)]+R4[υ(CC)](5)+R1[γ(CH2)](5)
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ρ’[Me1(CH3)](51)+ρ’[Me2(CH3)](12)
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R2[δtrig](24)+R1[γ(CH2)](18)+R3[υ(CC)](13)+ R4[γ(CH2)](5)
1196
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1269
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R3[υ(NC)](30)+R4[γ(CH2)](6)+R3[υ(CC)](6)+ R5[υ(CC)](5)+ρ’[Me2(CH3)](5)
1193
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ρ’[Me2(CH3)](15)+R5[δin(CH)(15)+υ(CC)(7)]+ R3[υ(NC)](13)
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[ρ(69)+ρ’(22)] Me2(CH3)
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[ρ(73)+ρ’(20)] Me1(CH3)
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R3[υ(NC)](14)+υ(CC)(11)]+R2[δin(CH)](21)+ R2[υ(CC)](20)
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R5[δin(CH)(21)+υ(CC)(16)]+R4[ω(CH2)](16)+ υ(CC)(6)]+R3[ρ’(CH)](10)
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R2[δtrig(12)+δin(CH)(13)]+R1[γ(CH2)](22)+R3[ γ(CH2)](14)
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R3[γ(CH2)](30)+R4[γ(CH2)](23)+R1[γ(CH2)](1 0)
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R4[υ(NC)](33)+R3[γ(CH2)(11)+υ(NC)(5)]+R2 [δtrig](11)
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R1[ρ(CH2](88)
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υ(C20O)(35)+R5[δin(CH)](8)+R4[υ(CC)](7)+υ (C19O)(6)
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R3[ρ(CH2)](17)+υ(C19O)(13)+R4[υ(CC)](8)+ R3[puck](6)+υ(C20O)(6)
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R3[ρ(CH2)(18)+υ(CC)(8)+puck(8)]+υ(C19O)(8 )+R4[υ(CC)](7)+υ(C20O)(6)
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R1[υ(CO)](21)+R3[υ(CC)](20)+R4[υ(CC)](9)+ υ(C19O)(8)+υ(C20O)(6)+R2[δa](6)
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R1[υ(CO)(67)+δring (11)+υ(CC)(5)]
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R4[υ(CC)(28)+υ(NC)(6)]+R3[ρ(CH2)(12)+ρ(C H2)(8)+υ(NC)(6)]
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R4[ρ(CH2)(40)+puck(14)]+R3[υ(CC)](13)
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υ(C19O)(27)+R4[ρ(CH2)(16)+δtrig(7)]+R3[ρ(C H2)](5) R4[ρ(CH2)(38)+R3[υ(CC)](6)+υ(C20O)(5)
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R3[υ(CC)(14)+ρ(CH2)(8)]+υ(C19O)(11)+R4[υ (CC)](9)+R5[δa](6)+υ(C20O)(6)
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R1[υ(CO)](73)+R1[δ’ring](6)
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R5[oop(CH)(75)+puck(7)]
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R3[ρ(CH2)(22)+δtrig(8)]+R4[δtrig](6)+R5[oop(C H)](9)
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R4[υ(CC)(11)+ρ(CH2)(9)]+R2[oop(CH)](16)+ R3[ρ(CH2)(12)+υ(NC)](5)
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R2[oop(CH)](73)+R2[τ’](5)
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R2[oop(CH)](23)+R2[puck](7)+R5[δ’a](6)+R1 [υ(CO)] (5)
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R2[oop(CH)](66)+R2[puck](11)
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R1[υ(CO)(22)+υ(CC)(13)+δring(5)]+R2[υ(CC)( 10)+δ’a(9)]
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R5[oop(CH)(73)+puck(10)+τ(6)+oop(C9O)(5)]
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R5[puck(25)+oop(C9O)(17)+oop(C10O)(6)+R 3[υ(NC)(13)+ρ(CH2)(6)]
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R5[puck(29)+oop(C9O)(17)+oop(C10O)(8)+oo p(CH)(5)]
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R1[δ’ring](16)+R3[υ(CC)](10)+R5[δtrig](6)+R2[ υ(CC)](6)
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R2[δtrig](17)+R1[δ’ring](16)+R5[δtrig](10)
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R2[puck](47)+R1[δring](13)+R3[puck](7)+τ(C3 5C12)(5)
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R1[δring(37)+υ(CO)(6)]+R2[puck(20)+δ’a(11)]
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R5[puck(12)+υ(CC)(10)+υ(CO)(6)]+R4[υ(CC) ](15)
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R2[τ(24)+puck(6)]+R1[δ’ring(12)+τ(8)]+R3[δtrig ](13)
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R2[τ(23)+δa(11)]+R3[puck](10)
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R5[δin(CO)(21)+puck(7)+υ(CC)(6)+δ’a(5)]+R4 [δ’a(9)+δtrig(6)]+δ(C10C20O)(7)
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R5[τ(18)+puck(14)+oop(CO)(13)]+R4[τ(9)+pu ck(8)] R5[τ’(14)+oop(CO)(11)+puck(5)]+τ(N1C15)(7 )+R3[δ’a](6)+R4[δ’a](5)
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R5[oop(CO)(19)+τ’(12)+τ(8)+R2[δ’a](7)
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R3[δ’a(26)+δa(10)]+R5[δin(CO)](6)+τ(N1C15)( 5)
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R4[δ’a(17)+δa(9)+ρ(CH2)(5)]+R5[δ’a(12)+τ’(8) +δa(5)]
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R5[δa(18)+τ’(5)]+δ(C10C20O)](12)+R3[δa](7)
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R2[τ’(27)+δa(24)]+τ(C4C16)(8)+R5[δa](5)+R3[ puck](5)
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R2[τ’(31)+δa(23)]+τ(C4C16)(17)+τ(C2C18)(8)
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R4[δa(20)+τ(5)]+R5[τ’](15)+δ(C10C20O)](13) +δ(C9C19O)](8)
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R3[δ’a(15)+δa(15)+puck(7)]+τ(N1C15)(10)
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τ(C2C18)(33)+R5[τ’](8)+R2[τ’](8)+R5[oop(C1 0O)](6)
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τ(C2C18)(19)+R5[τ’(11)+oop(C10O)(8)]+R4[p
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R5[δ’a(11)+τ’(9)+δa(5)+oop(CO)(5)]+R3[δa](1 2)+R2[δ’a](8)+R4[puck](5)
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R5[δin(C9O)](11)+δ(C10C20O)](9)+R4[δa](8)+ τ(C8C13)(5)
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τ(C8C13)(31)+δ(C9C19O)](12)+R4[τ](9)+R4[τ ’](8)+R5[τ](6)+R5[puck](5)
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τ(N1C15)(20)+R5[δin(C9O)](12)+τ(C2C18)(10 )+R3[τ](6)+R1[τ’](5)
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τ(C2C18)(18)+R3[puck](18)+R2[puck](12)+R 3[τ](12)+R1[τ](9)+R4[puck](5)
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R3[puck(12)+τ’(12)+δ’a(9)]+τ(C2C18)(7)+τ(N 1C15)(7)+R1[τ’](6)
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R4[τ’(15)+puck(7)]+R5[oop(C9O)](12)+τ(C20 O)(7)+R4[τ](6)+R5[τ’](5)+δ(C9C19O)](5)
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τ(C20O)(67)+τ(C8C13)(6)+R4[puck](5)
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R4[puck(12)+τ’(5)]+R2[τ](9)+τ(C8C13)(9)+R1 [τ](8)+R3[τ](6)+R3[δa](5)
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R5[δin(C10O)(17)+oop(C9O)(14))]+R2[τ](8)+δ (C10C20O)](8)+R1[τ](5)+δ(C9C19O)](5) τ(N1C15)(27)+R1[τ’(19)+τ(8)]+R3[τ](7)+τ(C4 C16)(6) +τ(C2C18)(5)
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R4[δa](17)+R5[oop(C9O)(9)+δin(C10O)(6)]+τ( C19O)(8)+R4[τ](5)+R1[τ](5)
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τ(C19O)(26)+τ(N1C15)(13)+τ(C8C13)(9)+R4[ puck](8)
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R1[τ’](34)+R5[τ](12)+R4[puck(9)+τ(9)]+τ(C8 C13)(11)+τ(N1C15)(6)
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R3[τ](17)+τ(N1C15)(16)+R1[τ](14)+τ(C4C16) (6)+R4[τ](6)+τ(C2C18)(5)+τ(C19O)(5)+R5[τ]( 5)+R2[τ](5)
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R1[τ’](43)+τ(C8C13)(8)+τ(C19O)(6)
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R3[τ’(13)+puck(6)]+τ(C10O)(12)+τ(C4C16)(9) +R4[τ](11)+R5[τ’](8)+τ(C2C18)(6)+R2[τ](5)+ τ(N1C15)(5)
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τ(C9O)(59)+δ(C9C19O)](8)+τ(C19O)(6)+R5[δ in(C9O)](5)
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τ(C10O)(37)+τ(C20O)(14)+τ(C9O)(9)+R4[τ’]( 8)+R3[τ’](5
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τ(N1C15)(31)+R3[puck](17)+R2[τ](9)+R3[τ](1 1)+τ(C10O)(7)+τ(C8C13)(6)
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τ(N1C15)(41)+R4[τ](20)+R3[τ’(12)+τ(5)]
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R4[τ’](30)+R3[τ](14)+τ(C4C16)(14)+τ(C8C13 )(14)+τ(N1C15)(14)
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Proposed assignments and potential energy distribution (PED) for vibrational normal modes. Types of vibration: ν, stretching; δ, deformation (bending), scissoring; oop, out-of-plane bending; ω, wagging; γ, twisting; ρ, rocking; τ, torsion; a Potential energy distribution (contribution ≥ 5).
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Graphical abstract
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ACCEPTED MANUSCRIPT Highlights ► FT-IR and FT-Raman spectra were recorded and compared with the theoretical results. ► The theoretical calculations were made using HF/DFT/B3LYP/6-311++G(d,p) method. ► The absorption spectrum has been compared with the experimental UV-Vis data. ► MEP surface have been plotted and reactivity descriptors have also been given.
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► The nonlinear optical properties have been calculated.
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Bhawani Datt Joshi, Anubha Srivastava, Poonam Tandon, Sudha Jain, A.P. Ayala PII: DOI: Reference:
S1386-1425(17)30807-7 doi:10.1016/j.saa.2017.10.008 SAA 15514
To appear in:
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
Received date: Revised date: Accepted date:
9 February 2017 3 September 2017 3 October 2017
Please cite this article as: Bhawani Datt Joshi, Anubha Srivastava, Poonam Tandon, Sudha Jain, A.P. Ayala , A combined experimental (IR, Raman and UV–Vis) and quantum chemical study of canadine. The address for the corresponding author was captured as affiliation for all authors. Please check if appropriate. Saa(2017), doi:10.1016/ j.saa.2017.10.008
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT A combined experimental (IR, Raman and UV-Vis) and quantum chemical study of canadine Bhawani Datt Joshia,b*, Anubha Srivastavac, Poonam Tandonc*, Sudha Jaind, A. P. Ayalab a
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Department of Physics, Siddhanath Sc. Campus, Tribhuvan University, 10406, Nepal. b Departamento de Fisica, Universidate Federal do Ceará, C. P. 6030, 60.455-900, Fortaleza, CE, Brasil. c Department of Physics, University of Lucknow, University Road, Lucknow 226 007, Uttar Pradesh, India. d Department of Chemistry, University of Lucknow, University Road, Lucknow 226007, Uttar Pradesh, India
________________________ *Corresponding author. Tel.: +977-9841580777; +91 522 2782653; fax: +91 522 2740840. E-mail address: [email protected], [email protected] (B. D. Joshi), [email protected] (P. Tandon)
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ACCEPTED MANUSCRIPT Abstract Plant based natural products cover a major sector of the medicinal field, as such focus on plant research has been increased all over the world. As an attempt to aid that research, we have performed structural and spectroscopic analysis of a natural product, an alkaloid: canadine. Both ab initio Hartree-Fock (HF) and density functional theory (DFT) employing
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B3LYP using 6-311++G(d,p) basis set were used for the calculations. The calculated
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vibrational frequencies were scaled and compared with the experimental infrared and Raman
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spectra. The complete vibrational assignments were made using potential energy distribution. The structure-activity relation has also been interpreted by mapping electrostatic potential
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surface and evaluating the reactivity descriptors, which are valuable information for quality control of medicines and drug-receptor interactions. Natural bond orbital analysis has also
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been performed to understand the stabilty and hyperconjogative interactions of the molecule. Furthermore, UV-Vis spectra have been recorded in an ethanol solvent (EtOH) and the
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electronic property has been analyzed employing TD-DFT for both gaseous and solvent
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phase. The HOMO and LUMO calculation with their energy gap show that charge transfer occurs within the molecule. Additionally, the nonlinear optical properties of the title
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compound have been interpreted that predicts it’s the best candidate for the NLO materials.
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Keywords: CAD, ab initio, DFT, vibrational spectroscopy, NBO, NLO properties
1. Introduction Literature reveals the traditional use of medicinal herb Goldenseal (Hydrastis canadensis L., belonging to the genus, Menispermaceae) for mild pathological conditions such as gastritis, colitis, duodenal ulcers, loss of appetite, and liver disease [1-3]. Benzylisoquinoline alkaloids viz; berberine, β-hydrastine, canadine, and canadaline have
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ACCEPTED MANUSCRIPT active components of Goldenseal. Canadine (CAD) possesses ventricular anti-fibrillatory effects (that may be attributed to its blockade of Na+, K+, and Ca2+ currents) [4], a potent inhibitor of platelet aggregation (in vitro and in vivo triggered by ADP, collagen, and arachidonic acid), and promising antithrombotic drug [5]. Having non-quaternary nitrogen and two non-aromatic rings, it has an antioxidant activity [6], and display very low
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cytotoxicity [7]. Algarra et al. [8] analyzed different separation techniques for CAD alkaloid
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in goldenseal extracts. Also, Pingali et al. [3] determined the crystalline structure of canadine
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molecule by single crystal diffraction technique. Its chemical structure is shown in the Fig. 1(a).
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Spectroscopic techniques, when combined with the quantum chemical calculations, are emerging as one of the most valuable methods for studying the structural behavior and to
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gain insight into the electronic structures of alkaloids at microscopic level [9, 10]. As the natural products show a diversity of chemical structures, in the recent years there has been
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increasing interest in the application of ab initio calculations to alkaloids as demonstrated in
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our earlier studies [9, 11, 12] as well as in others [13-16]. The theoretical investigations on the molecular properties can facilitate the solutions confronted in the experimental
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techniques.
A literature search reveals that neither the experimental infrared, Raman, and UV-Vis
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spectral analyses nor the theoretical calculations on molecular geometry, vibrational modes, natural bond orbital (NBO) and nonlinear optical (NLO) properties of the title molecule has been investigated so far. We would like to eliminate this deficiency observed in the literature. The main objective of this study is to investigate the structural and electronic properties of the title compound with the help of vibrational spectroscopic techniques and quantum mechanical calculations using both ab initio Hartree-Fock (HF) and the density functional theory (DFT) [17]. To understand the various conjugative and hyperconjugative interactions
3
ACCEPTED MANUSCRIPT as well intermolecular interactions that would form the H-bonded network within the molecule, natural bond orbital (NBO) analysis has been performed. Also, to interpret the structural-activity relationship and reactive sites of the molecule, molecular electrostatic potential (MEP) and reactivity descriptors have been calculated. Further, the nonlinear (NLO)
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property reveals that the title compound can be used as a good NLO material.
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2. Experimental details
Infrared spectra of CAD were recorded on a Bruker TENSOR 27 FT-IR spectrometer
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with a spectral resolution of 4 cm-1 in the region 300-4000 cm-1. Pellets of solid samples were
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prepared from mixtures of KBr and the sample in 200:1 ratio using a hydraulic press. The Raman spectra were recorded using an efficient visible Raman setup, Ar-514 nm,
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and 12 mW, at room temperature. An excitation laser of wavelength 514 nm was emitted from an Argon ion laser source with a power of 12 mW was used to record the vibrational
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spectra. The scattered Raman light was collected in a back scattering geometry using a
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microscope objective (ULW x50). The scattered light was dispersed using a monochromator with 1200 grooves/mm diffraction grating, and an entrance slit width of 200 micrometers.
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The Raman signals were detected using liquid nitrogen cooled charged coupled device (CCD) with an optimal sensitivity in the visible range. The total exposure time for each sample was
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5 sec and averaged over five accumulations. The ultraviolet absorption spectra of the molecule were examined in the range 200800 nm using a Varian - Cary 50 Bio, UV-Vis Spectrophotometer equipped with a 10 mm quartz cell. The UV pattern is taken from a 1x10-5 M solution of CAD, dissolved in ethanol at 20 ˚C.
3. Computational details
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ACCEPTED MANUSCRIPT The molecular structure, vibrational frequencies, and energies of the CAD were computed employing the DFT [17] method using Gaussian 09 program [18] package and Becke’s three parameters (local, non-local, Hartree-Fock) hybrid exchange functional with Lee-Yang-Parr correlation functional (B3LYP) [19-21]. First, the B3LYP/6-311++G(d,p) level of theory has been used for optimization protocol. Using these optimized parameters,
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the vibrational frequencies have been calculated at same level theory, which were used
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further for the spectra simulation. The split valence basis set 6-311++G(d,p) augmented by
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‘d’ polarization functions on heavy atoms and ‘p’ polarization functions on hydrogen atoms as well as diffuse functions for both hydrogen and heavy atoms [23, 24] have been used. The
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absolute Raman intensities and infrared absorption intensities were calculated in the harmonic approximation at the same level of theory as used for the optimized geometries.
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The vibrational assignments of normal modes were performed and the PED was calculated employing Gar2ped program [25] along with the internal coordinates using localized
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symmetry. For this purpose, a complete set of 132 internal coordinates were defined using
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Pulay’s recommendations [26, 27].
The graphical representation of the calculated Raman and IR spectra were made using
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GaussView program [28]. Visualization and confirmation of calculated data were done by using the Chemcraft program [29]. Isoelectronic molecular electrostatic potential surface
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(MEP) was mapped with GaussView program [28] using B3LYP/6-311++G(d,p) basis. Mulliken atomic charges, HOMO–LUMO gap (∆E), ionization potential, dipole moments and total energy have also been obtained for the optimized geometry. A theoretical time dependent density functional theory (TD-DFT) [23, 24] method was used to calculate the electronic absorption parameters in the gas phase, employing 6-31G basis set and the solvent effects (in EtOH solvent) were taken into account by means of integral equation formalism polarizable continuum model (IEF-PCM) [30-32]. NBO [17] analysis, which deals about the
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ACCEPTED MANUSCRIPT intra- and intermolecular charge delocalization between the bonds of a molecular system, has been performed at the DFT/B3LYP level of theory. Further, the reactivity descriptors have been calculated using B3LYP/6-31G(d,p) basis.
Geometry optimization and energies
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4.1.
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4. Results and discussions
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Starting from the molecular conformation of CAD in the asymmetric unit of the crystalline structure [3], the geometry optimization was performed as the first task without
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any constraints to the potential energy surface. The optimized structural parameters, using energy minimization, were used in vibrational frequency calculation to characterize all
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stationary points as minima. The ground state optimized structure of the molecule is presented in Fig. 1(b). The optimized structure is remarkably similar to the experimental one
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[3]. Both the optimized and experimental molecular conformations were compared by
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superimposing them using a least-square algorithm that minimizes the distance between the corresponding non-hydrogen atoms, as shown in Fig. S1 (Supplementary material). For
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clarity, all the hydrogen atoms are removed. The good agreement between the optimized and the experimental structure show that the optimized structure makes a replica of the
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experimentally observed conformation. The relative energies of the molecule are calculated employing ab initio HF and DFT functional. The energy calculated by DFT (-709572.532 kcal/mol) is lower, showing more stability, than the one calculated by HF (-705094.857 kcal/mol). The enthalpy difference between these two theories is 17.586 kcal/mol. A comparison of the optimized values of structural parameters (bond length, bond angle and torsion angle) with the observed values is given in Table S1 (Supplementary material). In general, the bond lengths do not differ by
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ACCEPTED MANUSCRIPT more than 0.02 Å, except the bonds O1-C18 and O3-C9, which differ by 0.06/0.07 and 0.015/0.03 Å in the DFT/HF, respectively. The bond angles do not differ by more than 3o, except the angles C9-O3-C19 and C6-N1-C15, which differ by 4.4/4.6o and 2.9/3.3o in the DFT/HF. Similarly, the dihedral angles do not differ by more than 10o, except the angles C20-O4-C10-C9, C20-O4-C10-C11, and C7-N1-C15-C14, which differ by 13.8/12.2o,
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4.2. Molecular Electrostatic Potential (MEP) Surface
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14.7/12.4o and 9.8/10.4o in the DFT/HF, respectively.
The MEP provides a visual method to understand the sites of the relative charge
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distribution in a molecule [12, 24]. In the generated surface, negative electrostatic potential colored in shades red, whereas, positive one colored in the shades of blue. A molecule shows
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its non-polar behavior if the surface is largely white or lighter color shades. Potential increases in the order red < orange < yellow < green < blue. The MEP of CAD mapped using
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the DFT/6-311++G (d,p) output is shown in the Fig. 2. The highest negative potential with
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red blobs is visible over the regions near nitrogen in ring and oxygen atoms of methoxy groups. The yellowish blob reflects less negative potential, is visible over the oxygen atoms
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of ring R1. A positive charge is localized near the hydrogen atoms of the methyl group. The
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value of Mulliken charges is presented in the Table S2 (Supplementary material).
4.3. Natural bond orbital (NBO) analysis NBO analysis is one of the efficient method for studying hybridization, conjugative interactions, covalence effects and charge transfer in polyatomic wave functions [11, 12]. The information from the first-order density matrix of the ab initio calculations develops a unique set of atomic hybrids and bond orbitals, which leads to “Lewis structure”. It helps in the investigation of intra- and intermolecular interactions among bonds. In the present work,
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ACCEPTED MANUSCRIPT utilizing the second-order micro-disturbance theory analysis, we have accounted some of the electron acceptors, donor orbitals and the interacting stabilization energy, E(2). The hyperconjugative interaction energy was deduced from the second-order perturbation approach [33-35]. The most important interaction between ‘‘filled’’ (donor) Lewis type NBOs and ‘‘empty’’ (acceptor) non-Lewis NBOs are reported in Table 1.
*C10-C11 bond of ring R5 which increase the ED (0.409e) leading to the
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C8-C9 to
electrons from C12-C13 and
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There occurs a strong hyperconjugative interaction of
NBO further conjugates with
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stabilization energy of 19.44 and 21.31 kcal/mol, respectively. This enhanced
*C10-C11
*C8-C9 resulting to high stabilization of 228.59 kcal/mol.
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Another hyperconjugative interactions were observed from
C4-C16 and
C17-C18 to
*C2-C3 bond of ring R2, and from C8-C9 and C10-C11 to *C12-C13 of ring R5 which
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increase the EDs of 0.366e and 0.363e, respectively. Similarly, the enhanced / *C2-C3 NBOs further conjugate to
*C17-C18
*C4-C16 leading to stabilization of 137.61/141.91
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kcal/mol, respectively. The interactions related to the resonance in the molecule, are electron
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donation from LP(2)O1/LP(2)O2 to antibond acceptors
*C17-C18 / *C2-C3 of ring R2
(24.98 /25.28 kcal/mol), and from LP(2)O4 to the antibond acceptor *C10-C11 of ring R5
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(27.78 kcal/mol). The interactions are confined between those atoms which are attached with the rings. A comparison of Mulliken and NBO charges is presented in the Table S2
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(Supplementary material).
Selected Lewis (bond or lone pair) NBO orbitals of investigated molecule with their valence hybrids corresponding to the various interactions are listed in Table S3 (Supplementary material). The valence hybrids analyses of NBO orbitals show that all the C– N bond orbitals are polarized towards the nitrogen atom (60.95 - 61.60% at N), whereas the C–O bond orbitals are polarized towards the oxygen atom (67.04 - 68.48% at O). Therefore, they consist with the maximum electron density on the nitrogen and oxygen atoms. The 8
ACCEPTED MANUSCRIPT electron density distribution around the imino group also influences the polarity of the compound.
4.4. Chemical reactivity
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4.41. Global reactivity descriptor
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Electrophilicity and hardness are two important molecular properties, which are
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useful for interpreting and understanding the stability and reactivity of molecular system [21]. According to the Hohenberg and Kohn (HK) theorems [17], the energy of the basic state of
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an electronic system is a functional of electron density. On the basis of Koopman’s theorem [21], global reactivity descriptors; electronegativity (χ), chemical potential (σ), global
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hardness (η), global softness (S) and global electrophilicity index (ω) were calculated using the energies of frontier molecular orbitals EHOMO, ELUMO and given by relations:
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χ = - ½[EHOMO + ELUMO]
η = ½[EHOMO + ELUMO]
ω = σ2/2η
………….. (4) …………… (5) ……………… (6)
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∆Nmax = - σ/η
………….. (3)
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S = ½(η)
……….. (2)
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σ = - χ = ½[EHOMO + ELUMO]
…….…….. (1)
According to Parr et al. 1999 [36] ω, a positive and finite quantity is a global reactivity index similar to
(a measure of the resistance of a system to transfer charge), and
σ. The direction of the charge transfer is completely determined by the electronic chemical
potential of the molecule because an electrophile is a chemical species capable of accepting electrons from the environments. Therefore, its energy must decrease upon accepting the electronic charge and electronic chemical potential must be negative. The values of frontier
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ACCEPTED MANUSCRIPT energy levels (EHOMO, ELUMO), energy band gap (ΔE), χ, σ, η, S, ω, and additional ΔN for CAD are listed in the Table S4 (Supplementary material). The calculated high value of the electrofilicity index (ω) shows that the molecule behaves as a strong electrophile.
4.42. Local Reactivity Descriptors
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Using Hirschfield population analysis of neutral, cation and anion state of molecule,
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Fukui functions (fk+, fk-, fk0) [36-39], are calculated at same calculation method B3LYP/6-21 G(d,p) using following relations: fk+ = [q(N+1) - q(N)] for nucleophilic attack
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……………….. (7)
fk- = [q(N) - q(N-1)] for electrophilic attack
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fk0 = ½[q(N+1) - q(N-1)] for radical attack
………………… (8) ………………. (9)
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where N, N-1 and N+1 are total electrons present in neutral, cation and anion state of molecule, respectively.
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Local softness (sk+, sk-, sk0) and local electrophilicity indices (ωk+, ωk-, ωk0), also used
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to describe the reactivity of atoms in the molecule, are calculated using the following equations:
sk+ = S fk+, sk- = S fk-, sk0 = S fk0
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………………… (10)
ωk+ = ω fk+, ωk- = ω fk-, ωk0= ω fk0
……………….. (11)
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where +, −, 0 signs show nucleophilic, electrophilic and radical attack, respectively. The calculated values of Fukui functions, electrophilicity descriptors, and the nucleophilicity descriptors are listed in the Table 2. The high value of fk- at O2 and O1 atoms indicate that these sites are more prone to nucleophilic attack. Similarly, the sites at C1, C12, and C20 are more prone to electrophilic attack due to having maximum value of fk+.
4.5. UV spectroscopy and HOMO-LUMO analysis
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ACCEPTED MANUSCRIPT The UV-Vis absorption spectrum of CAD is shown in the Fig. 3 with the absorption bands at 294 and 286 nm in EtOH solvent. Both the frontier molecular orbitals (FMOs), highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) are the most important orbitals participated in a chemical reaction. The transition of an electron between HOMO and LUMO is a principal factor that determines the easiness of
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chemical reaction and its path, irrespective to the intra- and intermolecular processes. Higher
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the gap between these two bands ( E) more is the stability of the system and vice versa.
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Here, we have demonstrated the molecular orbital both in the gas and solvent phases as an example to compare the effect of the solution on absorptions. The energy gap in gas phase as
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well as in the solvent phase is 5.508 eV and 5.411 eV, respectively. The calculated wavelengths (λmax), vertical excitation energies, oscillator strengths (f),
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dipole moments (μ), and excitation transition with spectral assignments for vacuum and the solvent environment are carried out as given in Table 3. The transition observed in the UV
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spectrum is π π*. In the gaseous phase in the LUMO, the charge is mainly accumulated on
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the ring R2 portions. Similarly, in HOMO and HOMO-1 the charge density is over the rings R2 and R3. However, in LUMO+1 it is over the ring R5 portion as shown in Fig. S2
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(Supplementary material). In solvent phase, the allowed dipole transition is at 261.32 nm (H
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L) with oscillator strength of 0.1363 and, in the gaseous phase, it is at 257.51 nm (H with oscillator strength of 0.0141. The H-1
L)
L transition is predicted at 252.05 nm with the
oscillator strength 0.0811 in the gas phase, while, H-1
L+1 transition at 290.14 nm is
predicted with oscillator strength 0.0240 in the solvent phase, respectively. The charge accumulation within the molecule in solvent phase is given in the Fig. S3 (Supplementary material).
4.6.
Vibrational spectrum 11
ACCEPTED MANUSCRIPT This CAD molecule has 46 atoms and hence gives 132 (3N-6; N the number of atoms) modes of vibrations. All the wavenumbers are both IR and Raman active. We have calculated these fundamental wavenumbers, their intensities and PED along with the internal coordinates obtained by HF and DFT with 6-311++G(d,p) basis set calculations. The wavenumbers predicted by HF method are larger than B3LPY due to the inclusion of electron
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correlation in the later. Since, the vibrational wavenumbers obtained from the DFT
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calculations are higher than the experimental wavenumbers, so the vibrational wavenumbers obtained from the DFT calculations were corrected by the wavenumber linear scaling (WLS)
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of Yoshida et.al. [40] by using the expression: υobs = (1.0087-0.0000163 υcal) υcal.
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The Raman scattering cross-sections, ∂σj/∂Ω, which is proportional to the Raman intensities may be calculated from the Raman scattering amplitude and predicted
h 8 2 c j
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24 4 45
4 0 j hc j 1 exp kT
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j
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wavenumbers for each normal modes using the relationship [41-43]:
Sj
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where, sj and υj are the scattering activities and the predicted wavenumbers (in cm-1), respectively of the jth normal mode, υo is the Raman exciting wavenumber (cm-1), and h, c
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and k are the universal constants. A comparison of the wavenumbers calculated by the DFT method shows very good agreement with the experimental values due to incorporation of electron correlation. The simulated and observed IR and Raman modes of the CAD molecule are given in Figs. 4 and 5, respectively. Out of several internal coordinates that may be present in the PED as given in Table 4, we have discussed here only some prominent modes:
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ACCEPTED MANUSCRIPT 4.6.1. Methoxy group vibration In a molecule containing methoxy group, the electronic charge is back donated from the lone pair atoms (oxygen) to the
* orbital of CH bond weakens the CH bonds. This
increases the CH bond resulting in the enhancement of the IR intensities in CH stretching [44, 45]. CH3 group has several modes associated with it, such as symmetric and asymmetric
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stretches, bends, rocks and torsions. There are two methyl groups (Me1 and Me2) connected to
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the same ring R5 as shown in the Fig. 1(b), forming methoxy groups. Asymmetric stretching
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modes associated to each Me1 and Me2 groups predicted in the range of 3000-2935 cm-1, were assigned in the weak IR and the strong Raman peaks. Symmetric stretching modes were
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predicted at 2902 and 2893 cm-1. Asymmetric deformations of Me1 and Me2 were assigned at 1493/1468 and 1485/1474cm-1 in the IR, and at 1491/1466 and 1480/1470 cm-1 in the Raman
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spectra, that is calculated at 1503/1473 and 1495/1481 cm-1, respectively. The calculated rocking vibrations at 1196/1166 cm-1 are in good agreements with 1186/1163 cm-1 in the IR
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and 1189/1164 cm-1 in the Raman peaks.
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.
4.6.2. Ring R1 vibrations
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Basically, six fundamental vibrational assignments can be associated with each CH2 moiety namely; symmetric and asymmetric stretch, deformation and rocking modes which
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belong to the polarized in-plane vibration. In addition to that, CH2 wagging and twisting would be expected to be depolarized out-of-plane symmetry [46]. The asymmetric stretching vibration of CH2 calculated at 2978 cm-1 and observed at 2997/3000 cm-1 in the IR/Raman spectrum. The symmetric stretching was observed at 2872/2868 cm-1 in the IR/Raman spectrum and calculated at 2886 cm-1 as shown in Table 4. Deformation mode of vibration predicted at 1537 cm-1 is in good agreement with the observed IR/Raman band at 1531/1533 cm-1. Highly mixed CH2 wagging, twisting and rocking vibrations were predicted at 1419,
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ACCEPTED MANUSCRIPT 1206 and 1138 cm-1, respectively.
4.6.3. Ring R2 vibrations The carbon-hydrogen stretching vibrations give rise to the weak bands in the region 3100-3000 cm−1 in all the aromatic compounds [47]. In the present case, the CH stretching
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modes were observed in this range with 100% contributions in PED. These bands are weak in
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the IR and medium strong in the Raman spectra. The in-plane deformation observed as the weak IR peak at 1495 cm-1 and the strong Raman peak at 1493 cm-1 and predicted at 1511
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cm-1. The out-of-plane deformations were calculated below 875 cm-1.
4.6.4. Ring R3 vibrations
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The CH stretching vibration predicted at 2766 cm-1 was assigned to IR/Raman peak at 2750/2753 cm-1. The rocking mode was observed at 1339/1345 cm-1 in the IR/Raman spectra.
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The mixed NC stretching vibrations were predicted at 1184 and 1159 cm-1 in the scaled DFT.
4.6.5. Ring R4 vibrations
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The CH2 asymmetric stretching vibrations predicted at 2958/2949 cm-1 were assigned to the strong Raman peaks at 2946/2940 cm-1 and the weak IR peaks at 2939/2937 cm-1. The
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calculated symmetric stretching vibrations for these modes are 2914 and 2784 cm-1. Their deformation, wagging, twisting and rocking vibrations are predicted at 1480/1472, 1377/1363, 1311/1274 and 1025 cm-1, respectively. The ring CC stretching vibration predicted at 1145 cm-1 is in good agreement with the observed IR/Raman peak at 1142/1140 cm-1.
4.6.6. Ring R5 vibrations
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ACCEPTED MANUSCRIPT The CH stretching vibrations associated with this ring were predicted at 3079 and 3040 cm-1. The CH in-plane bending was calculated at 1234 cm-1 corresponding to the observed peak at 1227 and 1233 cm-1 in the IR and Raman spectra, respectively. The out-ofplane deformation vibration of this mode was predicted at 924 and 803 cm-1. The calculated trigonal ring deformation mixed with the CO stretching vibration at 1248 cm-1 was found to
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be consistent with the recorded values at 1248/1241 cm-1 in the IR/Raman spectra. Another
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CO stretching mode vibration was predicted at 1293 cm-1. The CO in-plane deformation
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calculated at 651 cm-1 was assigned at 654/ 651 cm-1 in the IR/Raman spectra.
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4.7. Nonlinear optical (NLO) properties
Nonlinear optics deals with the interactions of various materials in applied
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electromagnetic fields to generate new field altered in phase, frequency, amplitude or other physical properties [48]. Some organic substances with
electronic system exhibit the largest
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known nonlinear coefficients and show promise for thin fabrication, allowing the enormous
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function and cost integrated electronic circuitry. The total dipole moment (μo), mean polarizability (∆α), the anisotropy of the
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polarizability (| |) and the total first hyperpolarizability (βo) using x, y, z components [39, 49] are calculated from the Gaussian 09 output and listed in the Table S5 (Supplementary
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material). In this study, the calculated values of μo , |
| and βo are 1.92 Debye, 32.76 x10-24
esu and 1200.87 x10-33 esu, respectively which are higher than those of urea (μo = 1.528 Debye, βo = 343.27 x 10-33 esu.) [50, 51]. These values are very much comparable with brucine/ strychnine (3.18/3.30 Debye, 39.47 x10-23/33.63 x10-23 esu and 221.97 x10-34/111.58 x10-34 esu) [13] and the p-NA [52]. From the above results, it appears that the title compound can be used as a good nonlinear material for the optical devices.
15
ACCEPTED MANUSCRIPT 5. Conclusion Present work is mainly concentrated on the study of the wavenumber assignments of CAD by using IR and Raman data together with the quantum chemical calculations. Both the IR and Raman spectra were in good agreements with the modes calculated by the DFT. A comparison of the scaled wavenumbers obtained using DFT methods have better accuracy
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with the experimental modes than HF due to the fact that the former includes some of the
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electron correlation effects. The observed electronic spectra have some higher values (294
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and 286 nm) compared with the theoretical absorption data (258 and 252 nm) and the molecular orbital coefficient analysis suggests that the electronic transitions are assigned to π*. NBO analysis shows the stability and charge delocalization from various bonding to
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π
anti-bonding orbitals ( *) of the title compound. MEP studies suggest that the nitrogen and
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oxygen (of the methoxy groups) atoms are the most reactive sites. The reactivity descriptors also tell that O2 and O1 atoms are more prone to nucleophilic attack. The observed
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microscopic NLO properties suggest its potential use in the development of NLO materials. It
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is reported that the title compound possesses anti-fibrillatory and antioxidant activity as well as behaves as a potent inhibitor of platelet aggregation. To predict and confirm these types of
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activity theoretically, molecular docking studies will be performed which are very useful for
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the industrial and biologically active compounds.
Acknowledgments:
B.D. Joshi would like to thank the CNPq-TWAS for fellowship (CNPq-TWAS/PostDoc/2014/ FR number: 3240279899) to pursue Post-Doc study in UFC, Fortaleza, Brazil. A.S. thanks University Grants Commission (UGC), New Delhi for financial assistance under PDF for Women Scientist; grant no. F.15-1/2014-15/PDFWM-2014-15-GE-UTT-24257 (SAII). P.T. is thankful to DST, New Delhi for financial support under the Indo- Brasil project
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ACCEPTED MANUSCRIPT (grant no. DST/INT/Brazil/P-10/2013).
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G.A. Voth, P. Salvador, J.J. Dannerberg, S. Dapprich, A.D. Daniels, J. Farkas, B. Foresman, J.V. Ortiz, J. Cioslowski, and D.J. Fox, GAUSSIAN 09, Revision, Gaussian, Inc., Wallingford CT, USA, 2009. [19] C. Lee, W. Yang, R.G. Parr, Phys. Rev. 37 (1988) 785-789. [20] A.D. Becke, J. Chem. Phys. 98 (1993) 5648-5652. [21] R.G. Parr, W. Yang, Density Functional Theory of Atoms and Molecules, Oxford, New York, 1989.
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ACCEPTED MANUSCRIPT [22] E.D. Glendering, A.E. Reed, J.E. Carpenter, F. Weinhold, NBO Version 3.1, TCI, University of Wisconsin, Madison, 1998. [23] G.A. Petersson, A. Bennett, T.G. Tensfeldt, M.A. Allaham, W.A. Shirley, J. Mantzaris, J. Chem. Phys. 89 (1988) 2193-2218. [24] G.A. Petersson, M.A. Allaham, J. Chem. Phys. 94 (1991) 6081-6090.
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[25] J.M.L. Martin, C. Van Aslenoy, Gar2ped, University of Antwerp, 1995.
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[26] P. Pulay, G. Fogarasi, F. Pang, J.E. Boggs, J. Am. Chem. Soc. 101 (1979) 2550-2560.
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[27] G. Fogarasi, X. Zhou, P.W. Taylor, P. Pulay, J. Am. Chem. Soc. 114 (1992) 81918201.
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[28] A. Frisch, A.B. Nielson, A.J. Holder, Gauss View User Manual, Gaussian Inc, Pittsburgh, P.A., 2000.
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[29] G.A. Zhurko, D.A. Zhurko, Chemcraft 2005,
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[31] S. Miertus, J. Tomasi, Chem. Phys. 65 (1982) 239-247.
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[32] M. Cossi, V. Barone, R. Cammi, J. Tomasi, Chem. Phys. Lett. 255 (1996) 327-335. [33] M.W. Wong, Chem. Phys. Lett. 256 (1996) 391-399.
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[34] A.P. Scott, L. Radom, J. Phys. Chem. 100 (1996) 16502-16513. [35] F. Weinhold, C.R. Landis, Valency, and bonding: A Natural Bond Orbital Donor-
AC
Acceptor Perspective, Cambridge University Press, New York, 2005. [36] R.G. Parr, L. Szentpály, S. Liu, J. Am. Chem., Soc. 121 (1999) 1922-1924. [37] R.G. Parr, R.G. Pearson, J. Am. Chem. Soc., 105 (1983) 7512-7516. [38] P. Geerlings, F. De Proft, W. Langenaeker, Chem. Rev., 103 (2003) 1793-1874. [39] P.K. Chattaraj, S. Giri, J. Phys. Chem. A, 111 (2007) 11116-11121. [40] H. Yoshida, K. Takeda, J. Okamura, A. Ehara, H. Matsurra, J. Phys. Chem. A 106 (2002) 3580-3586.
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ACCEPTED MANUSCRIPT [41] P. Pulay, G. Fogarasi, G. Pongor, J.E. Boggs, A. Vargha, J. Am. Chem. Soc., 105 (1983) 7037-7047. [42] G.A. Guirgis, P. Klaboe, S. Shen, D.L. Powell, A. Gruodis, V. Aleksa, C.J. Nielsen, J. Tao, C. Zheng, J.R. Durig, J. Raman Spectrosc. 34 (2003) 322-336. [43] P.L. Polavarapu, J. Phys. Chem. 94 (1990) 8106-8112.
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sixth ed., John Wiley & Sons Inc., New York, 2003.
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[44] R.M. Silverstein, F.X. Webster, Spectroscopic Identification of Organic Compounds,
SC
[45] P. Agarwal, N. Choudhary, A. Gupta, P. Tandon, Vibrational Spectrosc. 64 (2013) 134-147.
NU
[46] B.D. Joshi, A. Srivastava, P. Tandona, S. Jain, Spectrochim. Acta A 82 (2011) 270278.
MA
[47] B. Smith, Infrared Spectral Interpretation. A Systematic Approach, CRC Press, Washington, DC, 1999.
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[48] D.J. Williams, Angew. Chem. Int. Ed. Engl. 23 (1984) 690-703.
PT E
[49] H. Alyar, Z. Kantarci, M. Bahat, E. Kasap, J. Mol. Struct. 834-836 (2007) 516-520. [50] N. Sundaraganesan, J. Karpagam, S. Sebastian, J.P. Cornard, Spectrochim. Acta A 73
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(2009) 11–19.
[51] K. Chandramohan, K. Ravikumar, J. Chem. Cryst. 29 (1999) 121–125.
AC
[52] L. Jensen, P.D. Thvan, J. Chem. Phys., 123 (2005) 074307-7.
20
ACCEPTED MANUSCRIPT Figure captions Fig. 1(a). Chemical structure of CAD. Fig. 1(b). Optimized structure of CAD. Fig. 2. MEP mapped (from -4.389e-2 to +4.389e-2). Fig. 3. UV-Vis spectra taken in ethanol.
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Fig. 4. Comparison between observed and the calculated FT-IR spectra.
RI
Fig. 5. Comparison between observed and the calculated FT-Raman spectra.
Fig. S2. HOMO-LUMO plot in the gas phase.
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Fig. S3. HOMO-LUMO plot in the solvent phase.
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Fig. S1. Overlapping between experimental (purple) and the optimized molecular structures.
21
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22
Fig. 1
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ACCEPTED MANUSCRIPT
23
Fig. 2
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24
Fig. 3
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25
Fig. 4
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Fig. 5
26
ACCEPTED MANUSCRIPT Table 1 Second Order Perturbation Theory Analysis of Fock Matrix.
LP(2)O1
Acceptor NBO(j)
1.86493
1.86334
E(2)a kcal/mol
ED/e
[E(j)-E(i)]b
[Fi,j]c
au
au
*C17 – C18
0.36546
24.98
0.36
0.090
*C1 – H1
0.03904
6.29
0.68
0.060
*C2 – C3
0.36557
25.28
0.36
0.090
*C1 – H2
0.03904
6.26
0.68
0.060
0.39
0.056
1.90851
*C8 – C9
0.37837
8.71
LP(2)O4
1.85085
*C10 – C11
0.40903
27.78
0.34
0.094
*C20 – H19
0.01957
5.75
0.69
0.058
*C6 – H6
0.03722
8.51
0.65
0.068
*C7 – H8
0.03865
0.65
0.067
0.02870
6.17
1.01
0.071
0.02884
6.37
1.01
0.072
1.87519
1.9644
*O1 – C18
C3 – C4
1.96576
*O2 – C2
C17 – C18
1.97090
*C2 – C18
0.03844
5.15
1.29
0.073
C2 – C18
1.97304
*C2 – C3
0.36557
5.08
1.29
0.072
C4 – C16
1.69172
*C17– C18
0.36546
18.46
0.27
0.064
*C2 – C3
0.36557
18.09
0.27
0.064
* C8 – C9
0.37837
21.56
0.28
0.07
*C10 – C11
0.40903
19.44
0.27
0.066
*C12 – C13
0.36307
19.33
0.30
0.068
*C10 – C11
0.40903
21.31
0.28
0.070
*C4 – C16
0.34877
17.72
0.32
0.068
*C2 – C3
0.36557
19.59
0.30
0.070
*C4 – C16
0.34877
18.38
0.32
0.069
*C17– C18
0.36546
19.56
0.30
0.069
*C12 – C13
0.36307
19.48
0.31
0.070
*C8 – C9
0.37837
17.13
0.30
0.065
*C4 – C16
0.34877
137.61
0.02
0.080
C17 – C18
C2 – C3
C10 – C11
*C17– C18
D
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C8 – C9
1.67477
1.67004
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C12 – C13
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8.39
C16 – C17
NU
LP(1)N1
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LP(2)O3
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LP(2)O2
ED/e
PT
Donor NBO(i)
1.71465
1.71267
1.68223
0.36546
27
ACCEPTED MANUSCRIPT *C2 – C3
0.36557
*C4 – C16
0.34877
141.91
0.02
0.08
*C10 – C11
0.40903
*C12 – C13
0.36307
159.12
0.02
0.081
*C8 – C9
0.37837
228.59
0.01
0.082
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Energy E(2) ≥ 5 kcal mol-1 is assigned. a (2) E means energy of hyper conjugative interaction (stabilization energy). b Energy difference between donor and acceptor i and j NBO orbitals. c F(i, j) is the Fock matrix element between i and j NBO orbitals
28
ACCEPTED MANUSCRIPT Table 2 Atomic charges (in esu), Fukui functions (f+k,f--k); Local softness (s+k,s-k)); and local electrophilicity indices (ω+k, ω-k)); in eV for atomic sites, using Hirshfeld population analysis at B3LYP/6-31G(d,p) level. Fukui functions
Local softness
Local electrophilicity indices
qN-1
f+k
f--k
s+k
s-k
ω+k
ω -k
1 O
-0.165488
-0.122057
-0.180717
0.043431
0.015229
0.059801
0.020969
0.058922
0.020661
2 O
-0.164636
-0.114692
-0.185035
0.049944
0.020399
0.068769
0.028088
0.067759
0.027675
3 O
-0.169553
-0.144161
-0.176066
0.025392
0.006513
0.034963
0.008968
0.034449
0.008836
4 O
-0.148781
-0.107017
-0.150034
0.041764
0.001253
0.057506
0.001725
0.056661
0.001700
1 N
-0.120830
-0.083205
-0.121785
0.037625
0.000955
0.051807
0.001315
0.051046
0.001296
1 C
0.233609
0.302269
0.167463
0.068660
0.066146
0.094539
0.091078
0.093150
0.089740
2 C
0.052989
0.092700
0.009552
0.039711
0.043437
0.054679
0.059809
0.053876
0.058931
3C
-0.008032
0.038037
-0.116305
0.046069
0.108273
0.063433
0.149083
0.062501
0.146893
4 C
-0.015226
0.019149
-0.033162
0.034375
0.017936
0.047332
0.024696
0.046636
0.024334
5 C
0.018291
0.063392
-0.022792
0.045101
0.041083
0.062100
0.056568
0.061188
0.055737
6 C
0.052459
0.097040
0.010711
0.044581
0.041748
0.061384
0.057484
0.060483
0.056639
7 C
0.059514
0.100245
0.003940
0.040731
0.055574
0.056083
0.076521
0.055259
0.075397
8 C
-0.020745
-0.013799
-0.045168
0.006946
0.024423
0.009564
0.033628
0.009424
0.033134
9 C
0.052690
0.089556
0.005925
0.036866
0.046765
0.050761
0.064392
0.050016
0.063446
10 C
0.059311
0.096577
0.035486
0.037266
0.023825
0.051312
0.032805
0.050558
0.032323
11 C
-0.034798
0.007966
-0.105321
0.042764
0.070523
0.058882
0.097104
0.058018
0.095678
12 C
-0.014170
0.044029
-0.106163
0.058199
0.091993
0.080135
0.126667
0.078958
0.124806
13 C
-0.020859
0.004017
-0.032678
0.024876
0.011819
0.034252
0.016274
0.033749
0.016035
14 C
0.016552
0.057367
-0.018815
0.040815
0.035367
0.056199
0.048697
0.055373
0.047982
15 C
0.048796
0.089400
0.024872
0.040604
0.023924
0.055908
0.032941
0.055087
0.032457
16 C
-0.017853
0.011469
-0.040174
0.029322
0.022321
0.040374
0.030734
0.039781
0.030283
17 C
-0.007228
0.023172
-0.105810
0.0304
0.098582
0.041858
0.135739
0.041243
0.133745
18 C
0.052136
0.084925
0.019574
0.032789
0.032562
0.045148
0.044835
0.044485
0.044177
19 C
0.118028
0.162462
0.051688
0.044434
0.06634
0.061182
0.091345
0.060283
0.090003
20 C
0.143607
0.200949
0.088600
0.057342
0.055007
0.078955
0.075740
0.077795
0.074628
AC
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qN+1
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qN
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Hirshfeld atomic charges
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Atom no.
29
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ACCEPTED MANUSCRIPT
30
ACCEPTED MANUSCRIPT Table 3 Electronic transitions, absorption wavelength λmax (nm), excitation energy (eV), oscillator strengths (f), frontier orbital energies (eV) and dipole moment (Debye). λmax
Excitation transition Solvent phase
H-1
3
H
L+1
H
4
H
L+2
5
H
L+3
6
H-1
L+2
H-1
7
H-1
L+3
8
H-2
L+3
Solvent phase
Gas phase
Solvent phase
Gas
Solvent
0.0141
0.1367
L
294
257.51
261.32
4.8148
4.7446
L+1
286
252.05
250.14
4.9191
4.9566
0.0811
0.0240
L+1
247.52
245.76
5.0091
5.0450
0.0118
0.0104
H
L+2
235.08
234.16
5.2740
0.0525
0.0369
H
L+3
228.96
230.84
L+2
219.71
222.06
H-1
L+3
216.06
218.62
H-4
L+1
210.84
200.35
H
L
Gas phase
H-1
ELUMO
Gas
-5.487369
Solvent
-5.534935
5.2949
5.4150
5.3709
0.0352
0.0964
5.6431
5.5833
0.0507
0.0495
5.7384
5.6712
0.0182
0.0229
5.8806
6.1884
0.0536
0.0967
E
µ (D)
0.020300
5.507669
1.8635
-0.124057
5.410878
2.0921
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EHOMO
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2
L
Calculated
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H
Calculated
Oscillatory strength (f) Calculated
SC
1
Expt
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Gas phase
E (eV)
MA
Excited states
31
Transition type/ assignments
π
π*
ACCEPTED MANUSCRIPT Table 4 Comparison between calculated and observed (FT-IR and micro-Raman) wavenumbers (cm-1) and the PED distribution of CAD. Calculated Unscaled
Observed Scaled
IR
Potential energy distribution (PED %)
Raman
HF
DFT
HF
3220
3367
3079
3212
3065
3069
R5[υ(CH)](99)
3216
3359
3075
3204
3038
3067
R2[υ(CH)](98)
3206
3344
3067
3191
3036
3038
R2[υ(CH)](98)
3177
3316
3040
3166
-
3025
R5[υ(CH)](99)
3148
3299
3014
3151
3001
3003
Me2[υa(CH3)](100)
3145
3279
3011
3133
2999
3002
Me1[υa(CH3)](99)
3109
3278
2978
3132
2997
3000
R1[υa(CH2)](99)
3098
3246
2969
3102
-
-
3086
3237
2958
3094
2939
2946
3077
3225
2949
3083
2937
3075
3222
2948
3081
2930
3074
3209
2947
3069
3069
3202
2942
3038
3189
2914
3032
3178
2908
3025
3166
2902
3015
3166
2893
3008
3162
2918
NU
SC
RI
PT
DFT
Me1[υa(CH3)](99)
3938
Me2[υa(CH3)](100)
2928
2930
R3[υa(CH2)](93)
3063
2926
2928
R3[υa(CH2)](98)
3051
2899
2897
R4[υs(CH2)](99)
3041
2897
2895
R3[υs(CH2)](97)
3030
2887
-
Me1[υs(CH3)](99)
3030
2885
2878
Me2[υs(CH3)](99)
2886
3027
2872
2868
R1[υs(CH2)](99)
3078
2805
2950
-
2805
R3[υs(CH2)](95)
2895
3068
2784
2942
2752
2755
R4[υs(CH2)](95)
2875
3046
2766
2921
2750
2753
R3[υ(CH)](94)+υa(CH2)(5)]
1677
1822
1646
1783
1622
1626
R2[υ(CC)(57)+δa(11)+δin(CH](5)]+R1[δring](8)
1674
1806
1642
1768
1618
1625
R2[υ(CC)(52)+[δ’a](11) +R1[υ(CC)](23)
1660
1798
1629
1760
1605
1607
R5[υ(CC)(51) +δa(11)+δin(CH)(8)]
1632
1769
1603
1733
1584
1586
R5[υ(CC)(51)+δ’a(10)+δin(CH)(6)]+R4[υ(CC)]
PT E
D
R4[υa(CH2)](99)
AC
2940
CE
MA
R4[υa(CH2)](96)
32
ACCEPTED MANUSCRIPT (21) 1680
1537
1649
1531
1533
R1[δ(CH2)](84)
1538
1662
1513
1631
1506
1501
R5[υ(CC)(32)+δin(CH)(26)]+R4[υ(CC)](15)+δa [Me2(CH3)](8)
1536
1655
1511
1625
1495
1493
R2[δin(CH)(29)+υ(CC)](24)]+R1[υ(CC)(19)+δ CH2](12)+υ(CO)(5)]
1527
1637
1503
1608
1493
1491
Me1(CH3)[(δa(56)+δ’(32)+ρ’(9)]
1522
1634
1497
1605
1491
1490
R3[δ(CH2)](67)+R4[δ(CH2)](13)+δ[Me2(CH3)] (5)
1519
1631
1495
1601
1485
1480
Me2(CH3)[δa(77)+ρ’(8)]+R3[δ(CH2)](6)
1505
1621
1481
1592
1474
1470
Me2(CH3)[δ’a(88)+ρ(5)]
1504
1621
1480
1592
1470
1468
R4[δ(CH2)](23)+δa[Me1(CH3)](21)+R3[δ(CH2) ](12)+R5[υ(CC)](8)+R5[υ(CO)](6)
1497
1617
1473
1588
1468
1466
Me1(CH3)[ δ’a(55)+δa(33)+ρ(7)]
1495
1611
1472
1583
1466
1461
1487
1604
1464
1576
1458
1485
1603
1462
1575
1456
1480
1600
1457
1573
1454
1473
1593
1451
1467
1587
1444
1440
1565
1419
1430
1550
1427
NU
SC
RI
PT
1563
MA
R4[δ(CH2)](48)+δs[Me1(CH3)](20)+δs[Me2(CH 3)](6)+R3[δ(CH2)](5) R3[δ(CH2)](88)
1455
δs[Me2(CH3)](66)+R4[δ(CH2)](15)
1453
R4[δ(CH2)](68)+δs[Me2(CH3)](10)+δs[Me1(CH 3)](7)
1450
1441
R2[υ(CC)](22)+R3[υ(CC)(10)+δtrig(5)+δa(5)]+ R4[δ(CH2)](6)+R1[ω(CH2)](6)
1559
1443
1439
δs[Me1(CH3)](34)+R5[υ(CC)](18)+R4[υ(CC)]( 6)
1539
1414
1426
R1[ω(CH2)](42)+R3[ω(CH2)](20)+R4[ω(CH2)] (8)
1409
1524
1408
1410
R1[ω(CH2)](36)+R3[ω(CH2)](24)+R4[ω(CH2)] (8)
1534
1406
1509
1406
1407
R2[υ(CC)](56)+R1[υ(CO)](5)
1396
1510
1377
1486
1358
1357
R4[ω(CH2)](31)+R3[CH(ρ’)(CH(20)+ω(CH2)( 8)]
1383
1497
1363
1474
1356
1355
R4[ω(CH2)](35)+υ(CC)(13)]+R3[ρ(CH)(13)+ω (CH2)](11)]
1371
1493
1352
1469
1348
1349
R3[(ω(40)+γ(10))CH2+υ(CC)(13)]
1363
1471
1344
1449
1339
1345
R3[ρ(CH)(40)+(ω(CH2)(19)+γ(CH2)(5)]
AC
1565
CE
PT E
D
1457
33
1329
1423
1325
1326
R5[υ(CC)](50)+R3[ρ’(CH)](9)+R4[υ(CC)](7)
1328
1436
1311
1415
1304
1303
R4[γ(24)+(5)](CH2)+R3[ρ’(CH)](17)+υ(N5C3 3)(5)+γ(CH2)(5)]+R5[υ(CC)](8)+δin(CH)(5)]
1317
1426
1300
1405
1300
1295
R4[υ(CC)](16)+υ(NC)(6)]+R5[υ(CC)](16)+R3[ γ(CH2)](14)
1310
1384
1293
1365
1281
1283
R5[υ(CO)(28)+δin(CH)(13)+υ(CC)(10)+R4[ω( CH2)](6)+R3[γ(CH2)](5)
1290
1378
1274
1359
1273
1277
R4[γ(CH2)](22)+R1[υ(CO)](11)+υ(CC)(9)]+R2 [υ(CC)(19)]+R3[γ(CH2)](7)
1270
1366
1254
1348
1250
1247
R2[δin(CH)](27)+R3[γ(CH2)(10)+δtrig(9)]+R4[γ (CH2)(10)+υ(NC)(5)]
1263
1352
1248
1334
1248
1241
R5[δtrig(24)+υ(CO)(23)]+R4[ω(CH2)(8)+υ(CC) ](7)
1256
1349
1241
1331
1229
1239
R4[γ(CH2)](25)+R2[υ(CC)(22)+δin(CH)(6)]+R 1[υ(CC)(7)+υ(CO)(9)]
1248
1329
1234
1311
1227
1233
1236
1327
1222
1309
1213
1225
1324
1212
1307
1211
1219
1314
1206
1297
-
1198
R1[γ(CH2)](32)+R4[γ(CH2)(21)+R2[δin(CH)(7) ]+R2[δin(CH)](6)
1213
1310
1200
1293
-
1196
ρ’[Me2(CH3)](29)+R5[δin(CH)(15)+δtrig(7)]+υ( CC)(6)]+R4[υ(CC)](5)+R1[γ(CH2)](5)
1210
1307
1196
1291
1186
1189
ρ’[Me1(CH3)](51)+ρ’[Me2(CH3)](12)
1202
1298
1189
1282
1184
1187
R2[δtrig](24)+R1[γ(CH2)](18)+R3[υ(CC)](13)+ R4[γ(CH2)](5)
1196
1285
1184
1269
1182
1185
R3[υ(NC)](30)+R4[γ(CH2)](6)+R3[υ(CC)](6)+ R5[υ(CC)](5)+ρ’[Me2(CH3)](5)
1193
1279
1180
1264
1180
1183
ρ’[Me2(CH3)](15)+R5[δin(CH)(15)+υ(CC)(7)]+ R3[υ(NC)](13)
1178
1278
1166
1263
1163
1164
[ρ(69)+ρ’(22)] Me2(CH3)
1177
1258
1165
1243
1162
1162
[ρ(73)+ρ’(20)] Me1(CH3)
1171
1252
1159
1237
1159
1160
R3[υ(NC)](14)+υ(CC)(11)]+R2[δin(CH)](21)+ R2[υ(CC)](20)
CE
AC
NU
SC
RI
PT
1444
PT E
1347
D
ACCEPTED MANUSCRIPT
MA
R5[δin(CH)(21)+υ(CC)(16)]+R4[ω(CH2)](16)+ υ(CC)(6)]+R3[ρ’(CH)](10)
1216
R2[δtrig(12)+δin(CH)(13)]+R1[γ(CH2)](22)+R3[ γ(CH2)](14)
1212
R3[γ(CH2)](30)+R4[γ(CH2)](23)+R1[γ(CH2)](1 0)
34
ACCEPTED MANUSCRIPT 1222
1150
1208
1140
1146
R4[υ(NC)](33)+R3[γ(CH2)(11)+υ(NC)(5)]+R2 [δtrig](11)
1149
1210
1138
1196
1130
1131
R1[ρ(CH2](88)
1121
1193
1110
1180
1082
1083
υ(C20O)(35)+R5[δin(CH)](8)+R4[υ(CC)](7)+υ (C19O)(6)
1099
1187
1088
1174
1080
1081
R3[ρ(CH2)](17)+υ(C19O)(13)+R4[υ(CC)](8)+ R3[puck](6)+υ(C20O)(6)
1088
1182
1078
1170
1078
1079
R3[ρ(CH2)(18)+υ(CC)(8)+puck(8)]+υ(C19O)(8 )+R4[υ(CC)](7)+υ(C20O)(6)
1080
1167
1070
1155
1051
1065
R1[υ(CO)](21)+R3[υ(CC)](20)+R4[υ(CC)](9)+ υ(C19O)(8)+υ(C20O)(6)+R2[δa](6)
1073
1161
1063
1149
1049
1052
R1[υ(CO)(67)+δring (11)+υ(CC)(5)]
1054
1144
1045
1133
1042
1040
R4[υ(CC)(28)+υ(NC)(6)]+R3[ρ(CH2)(12)+ρ(C H2)(8)+υ(NC)(6)]
1034
1128
1025
1117
1018
1021
R4[ρ(CH2)(40)+puck(14)]+R3[υ(CC)](13)
1016
1120
1008
1110
993
1007
991
1104
983
1093
979
978
1074
971
1065
957
973
1050
966
1041
955
930
1043
924
921
1002
915
901
997
895
876
976
874
NU
SC
RI
PT
1162
MA
υ(C19O)(27)+R4[ρ(CH2)(16)+δtrig(7)]+R3[ρ(C H2)](5) R4[ρ(CH2)(38)+R3[υ(CC)](6)+υ(C20O)(5)
959
R3[υ(CC)(14)+ρ(CH2)(8)]+υ(C19O)(11)+R4[υ (CC)](9)+R5[δa](6)+υ(C20O)(6)
PT E
D
980
957
R1[υ(CO)](73)+R1[δ’ring](6)
-
919
R5[oop(CH)(75)+puck(7)]
994
910
912
R3[ρ(CH2)(22)+δtrig(8)]+R4[δtrig](6)+R5[oop(C H)](9)
990
883
884
R4[υ(CC)(11)+ρ(CH2)(9)]+R2[oop(CH)](16)+ R3[ρ(CH2)(12)+υ(NC)](5)
871
969
881
874
R2[oop(CH)](73)+R2[τ’](5)
966
870
959
860
863
R2[oop(CH)](23)+R2[puck](7)+R5[δ’a](6)+R1 [υ(CO)] (5)
867
938
863
932
858
861
R2[oop(CH)](66)+R2[puck](11)
834
911
830
905
820
824
R1[υ(CO)(22)+υ(CC)(13)+δring(5)]+R2[υ(CC)( 10)+δ’a(9)]
807
896
803
891
804
805
R5[oop(CH)(73)+puck(10)+τ(6)+oop(C9O)(5)]
781
865
778
861
775
776
R5[puck(25)+oop(C9O)(17)+oop(C10O)(6)+R 3[υ(NC)(13)+ρ(CH2)(6)]
AC
CE
1035
35
ACCEPTED MANUSCRIPT 840
758
835
767
755
R5[puck(29)+oop(C9O)(17)+oop(C10O)(8)+oo p(CH)(5)]
754
818
751
814
750
753
R1[δ’ring](16)+R3[υ(CC)](10)+R5[δtrig](6)+R2[ υ(CC)](6)
746
812
743
809
748
751
R2[δtrig](17)+R1[δ’ring](16)+R5[δtrig](10)
735
805
733
801
-
720
R2[puck](47)+R1[δring](13)+R3[puck](7)+τ(C3 5C12)(5)
722
797
720
793
717
718
R1[δring(37)+υ(CO)(6)]+R2[puck(20)+δ’a(11)]
716
765
714
763
706
708
R5[puck(12)+υ(CC)(10)+υ(CO)(6)]+R4[υ(CC) ](15)
689
759
687
756
687
689
R2[τ(24)+puck(6)]+R1[δ’ring(12)+τ(8)]+R3[δtrig ](13)
669
728
667
725
667
660
R2[τ(23)+δa(11)]+R3[puck](10)
652
700
651
698
654
651
R5[δin(CO)(21)+puck(7)+υ(CC)(6)+δ’a(5)]+R4 [δ’a(9)+δtrig(6)]+δ(C10C20O)(7)
615
674
614
672
619
610
566
625
566
624
559
558
605
558
605
557
532
571
532
571
530
518
556
518
510
552
511
501
539
446
NU
SC
RI
PT
761
MA
R5[τ(18)+puck(14)+oop(CO)(13)]+R4[τ(9)+pu ck(8)] R5[τ’(14)+oop(CO)(11)+puck(5)]+τ(N1C15)(7 )+R3[δ’a](6)+R4[δ’a](5)
558
R5[oop(CO)(19)+τ’(12)+τ(8)+R2[δ’a](7)
515
516
R3[δ’a(26)+δa(10)]+R5[δin(CO)](6)+τ(N1C15)( 5)
552
509
510
R4[δ’a(17)+δa(9)+ρ(CH2)(5)]+R5[δ’a(12)+τ’(8) +δa(5)]
501
539
507
505
R5[δa(18)+τ’(5)]+δ(C10C20O)](12)+R3[δa](7)
484
447
485
442
440
R2[τ’(27)+δa(24)]+τ(C4C16)(8)+R5[δa](5)+R3[ puck](5)
432
467
432
468
431
427
R2[τ’(31)+δa(23)]+τ(C4C16)(17)+τ(C2C18)(8)
407
440
407
440
405
410
R4[δa(20)+τ(5)]+R5[τ’](15)+δ(C10C20O)](13) +δ(C9C19O)](8)
388
424
389
425
-
388
R3[δ’a(15)+δa(15)+puck(7)]+τ(N1C15)(10)
381
415
382
416
-
383
τ(C2C18)(33)+R5[τ’](8)+R2[τ’](8)+R5[oop(C1 0O)](6)
373
400
374
401
-
375
τ(C2C18)(19)+R5[τ’(11)+oop(C10O)(8)]+R4[p
PT E
R5[δ’a(11)+τ’(9)+δa(5)+oop(CO)(5)]+R3[δa](1 2)+R2[δ’a](8)+R4[puck](5)
AC
531
CE
D
560
556
36
ACCEPTED MANUSCRIPT
374
346
375
-
340
R5[δin(C9O)](11)+δ(C10C20O)](9)+R4[δa](8)+ τ(C8C13)(5)
339
366
340
367
-
338
τ(C8C13)(31)+δ(C9C19O)](12)+R4[τ](9)+R4[τ ’](8)+R5[τ](6)+R5[puck](5)
300
333
301
334
-
292
τ(N1C15)(20)+R5[δin(C9O)](12)+τ(C2C18)(10 )+R3[τ](6)+R1[τ’](5)
286
312
287
313
-
288
τ(C2C18)(18)+R3[puck](18)+R2[puck](12)+R 3[τ](12)+R1[τ](9)+R4[puck](5)
268
292
269
293
-
269
R3[puck(12)+τ’(12)+δ’a(9)]+τ(C2C18)(7)+τ(N 1C15)(7)+R1[τ’](6)
254
270
255
271
-
248
R4[τ’(15)+puck(7)]+R5[oop(C9O)](12)+τ(C20 O)(7)+R4[τ](6)+R5[τ’](5)+δ(C9C19O)](5)
242
256
243
258
-
244
τ(C20O)(67)+τ(C8C13)(6)+R4[puck](5)
222
243
223
244
-
207
R4[puck(12)+τ’(5)]+R2[τ](9)+τ(C8C13)(9)+R1 [τ](8)+R3[τ](6)+R3[δa](5)
195
211
196
213
-
201
188
204
189
205
-
181
191
182
192
148
159
148
141
150
141
125
140
126
111
128
89
PT E
-
NU
SC
RI
PT
345
D
uck](12)
MA
R5[δin(C10O)(17)+oop(C9O)(14))]+R2[τ](8)+δ (C10C20O)](8)+R1[τ](5)+δ(C9C19O)](5) τ(N1C15)(27)+R1[τ’(19)+τ(8)]+R3[τ](7)+τ(C4 C16)(6) +τ(C2C18)(5)
190
180
R4[δa](17)+R5[oop(C9O)(9)+δin(C10O)(6)]+τ( C19O)(8)+R4[τ](5)+R1[τ](5)
-
-
τ(C19O)(26)+τ(N1C15)(13)+τ(C8C13)(9)+R4[ puck](8)
151
-
140
R1[τ’](34)+R5[τ](12)+R4[puck(9)+τ(9)]+τ(C8 C13)(11)+τ(N1C15)(6)
141
-
122
R3[τ](17)+τ(N1C15)(16)+R1[τ](14)+τ(C4C16) (6)+R4[τ](6)+τ(C2C18)(5)+τ(C19O)(5)+R5[τ]( 5)+R2[τ](5)
112
129
-
109
R1[τ’](43)+τ(C8C13)(8)+τ(C19O)(6)
115
90
116
-
107
R3[τ’(13)+puck(6)]+τ(C10O)(12)+τ(C4C16)(9) +R4[τ](11)+R5[τ’](8)+τ(C2C18)(6)+R2[τ](5)+ τ(N1C15)(5)
82
104
83
104
-
-
τ(C9O)(59)+δ(C9C19O)](8)+τ(C19O)(6)+R5[δ in(C9O)](5)
74
71
75
71
-
-
τ(C10O)(37)+τ(C20O)(14)+τ(C9O)(9)+R4[τ’]( 8)+R3[τ’](5
AC
CE
160
37
ACCEPTED MANUSCRIPT 61
66
62
67
-
-
τ(N1C15)(31)+R3[puck](17)+R2[τ](9)+R3[τ](1 1)+τ(C10O)(7)+τ(C8C13)(6)
39
41
39
42
-
-
τ(N1C15)(41)+R4[τ](20)+R3[τ’(12)+τ(5)]
28
31
28
31
-
-
R4[τ’](30)+R3[τ](14)+τ(C4C16)(14)+τ(C8C13 )(14)+τ(N1C15)(14)
AC
CE
PT E
D
MA
NU
SC
RI
PT
Proposed assignments and potential energy distribution (PED) for vibrational normal modes. Types of vibration: ν, stretching; δ, deformation (bending), scissoring; oop, out-of-plane bending; ω, wagging; γ, twisting; ρ, rocking; τ, torsion; a Potential energy distribution (contribution ≥ 5).
38
D
MA
NU
SC
RI
PT
ACCEPTED MANUSCRIPT
AC
CE
PT E
Graphical abstract
39
ACCEPTED MANUSCRIPT Highlights ► FT-IR and FT-Raman spectra were recorded and compared with the theoretical results. ► The theoretical calculations were made using HF/DFT/B3LYP/6-311++G(d,p) method. ► The absorption spectrum has been compared with the experimental UV-Vis data. ► MEP surface have been plotted and reactivity descriptors have also been given.
AC
CE
PT E
D
MA
NU
SC
RI
PT
► The nonlinear optical properties have been calculated.
40