- Email: [email protected]
Synthesis, growth, structure, spectral, crystalline perfection and theoretical studies on (E)-N′-(diphenylmethylene)isonicotinohydrazide dihydrate crystals
Optik 125 (2014) 4181–4185
Contents lists available at ScienceDirect
Optik journal homepage: www.elsevier.de/ijleo
Synthesis, growth, structure, spectral, crystalline perfection and theoretical studies on (E)-N -(diphenylmethylene)isonicotinohydrazide dihydrate crystals V. Meenatchi a , K. Muthu a , M. Rajasekar a , G. Bhagavannarayana b , SP. Meenakshisundaram a,∗ a b
Department of Chemistry, Annamalai University, Annamalainagar 608 002, Tamilnadu, India National Physical Laboratory, New Delhi 110012, India
a r t i c l e
i n f o
a b s t r a c t
Article history: Received 19 July 2013 Accepted 13 January 2014
Single crystals of (E)-N -(diphenylmethylene)isonicotinohydrazide dihydrate have been grown by slow evaporation solution growth technique from ethanol at room temperature. The crystal belongs to triclinic ˚ b = 9.753(5) A, ˚ c = 11.007(5) A˚ system with the space group P 1¯ and the cell parameters are, a = 8.679(5) A, and V = 871.8(8) A˚ 3 . The functional groups present in the molecule are confirmed by Fourier transform
Keywords: Crystal structure Infrared spectroscopy UV–vis spectroscopy Theoretical calculation Hyperpolarizability
infrared spectroscopy and crystallinity by XRD. The crystals are transparent in the visible region and have a lower optical cut-off at ∼410 nm with a band gap energy of 3.14 eV, estimated by the application of Kubelka–Munk algorithm. The crystalline perfection as evaluated by high-resolution X-ray diffraction analysis reveals multi peaks. Theoretical calculations were performed using Hartree–Fock method with 6-31G(d,p) as the basis set for to derive the optimized geometry, dipole moment and first-order molecular hyperpolarizality (ˇ) values. © 2014 Elsevier GmbH. All rights reserved.
1. Introduction Organic single crystals possess unique optoelectronic properties because the molecules have delocalized electrons, namely, conjugated electron systems exhibiting various photoresponses such as photoconductive, photovoltaic, photocatalytic behavior and so on. The organic materials with intramolecular charge transfer compounds have large second-order nonlinear optical effects. Electron rich (donor) and deficient (acceptor) substituents provide the asymmetric charge distribution in the electron system, show large nonlinear optical responses. The chemistry of Schiff bases has been intensively investigated in recent years owing to their co-ordination properties and diverse applications. Schiff base hydrazones are widely used in analytical chemistry as selective metal extracting agents as well as in spectroscopic determination of certain transition metals [1,2]. The development of the field of bioinorganic chemistry has increased the interest in Schiff base complexes since it has been recognized that many of these complexes may serve as models for biologically important
∗ Corresponding author. Tel.: +91 4144 221670. E-mail addresses: [email protected], [email protected] (SP. Meenakshisundaram). http://dx.doi.org/10.1016/j.ijleo.2014.05.006 0030-4026/© 2014 Elsevier GmbH. All rights reserved.
species. Pyridine heterocycles are repeated moieties in many large molecules with interesting photophysical, electrochemical and catalytic applications [3–8]. The growth, structure and characterization of (E)-N -(diphenylmethylene)isonicotinohydrazide dihydrate (DPMI) have not been reported so far to the best of our knowledge. In the present study, we report the synthesis, growth, structure, dipole moment, hyperpolarizability and characterization of a new organic crystal, isonicotinohydrazide.
2. Experimental 2.1. Synthesis and crystal growth dihydrate (E)-N -(diphenylmethylene)isonicotinohydrazide (DPMI) was synthesized by mixing stoichiometric amounts of benzophenone and isoniazid in the molar ratio of 1:1. The reactants were dissolved in ethanolic medium with catalytic amount of concentrated sulphuric acid and refluxed for 3–5 h to form aryl acid hydrazone. The completion of the reaction was confirmed by thin layer chromatography. The reaction mixture was then poured in ice cold water and the precipitate obtained was filtered and dried. Purity of the compound was improved by recrystallization process using ethanol as a solvent.
4182
V. Meenatchi et al. / Optik 125 (2014) 4181–4185
N
O
O
C
NH NH2
C
C c on.H 2 S O 4
N
N
H
peaks around 1056 and 754 cm−1 are due to N N and aromatic C H out of plane bending vibrations respectively. 3.2. Optical studies The optical transmission spectrum of DPMI was recorded using 5E UV–vis spectrophotometer. The optical transmission spectrum (Fig. 3) shows the absorption is minimum in the visible region and cut-off wavelength is ∼ 410 nm. The Kubelka–Munk theory [9] provides a correlation between reflectance and concentration. The concentration of an absorbing species can be determined using the Kubelka–Munk formula,
3. Results and discussion F(R) =
3.1. FT-IR The FT-IR spectrum was recorded for DPMI crystal using an AVATAR 330 FT-IR by KBr pellet technique in the spectral range of 400–4000 cm−1 (Fig. 2). The absorption band at 1699 cm−1 is due to C O stretching vibration. The absorption band around 3254 cm−1 is due to N H stretching frequency. The C N stretching frequency appeared as sharp intensity band around 1639 cm−1 . An absorption band in the region 3000–3100 cm−1 is due to C H stretching frequency of aromatic ring. The band at 1498 cm−1 is due to C C stretching frequency of aromatic region. The absorption band around 1118 cm−1 is due to O C N stretching vibrations. The
N C
E th ano l
DPMI single crystals were grown using slow evaporation solution growth technique at room temperature. A saturated solution of DPMI in ethanol was prepared and the solution was stirred for 2–3 h at room temperature to obtain a homogenous solution. A beaker containing DPMI solution was tightly covered with a thin polythene sheet to control the evaporation rate of the solvent and kept undisturbed in a dust free environment. Numerous tiny crystals were formed at the bottom of the container due to spontaneous nucleation. Macroscopic defect-free crystals of DPMI were harvested after 9–11 days and the photographs of as-grown crystals are shown in Fig. 1.
O
(1 − R)2 a Ac = = 2R s s
where F(R) is Kubelka–Munk fuction, R is the reflectance of the crystal and s is scattering coefficient, A is the absorbance and c is concentration of the absorbing species. The measurement of [F(R)hv] as a function of hv provides the band gap energy Eg of the material. The direct band gap energy can be obtained from the intercept of the resulting straight lines with the energy axis at [F(R)hv]2 = 0 and the band gap energy of the specimen is deduced as 3.14 eV. The Tauc plot is given as inset in Fig. 3. 3.3. Powder XRD As-grown DPMI crystal was finely powdered and subjected to powder XRD analysis using a Philips X’pert pro Triple-axis X-ray diffractometer at room temperature using a wavelength of 1.540 A˚ and a step size of 0.008◦ . The samples were examined with CuK␣ radiation in 2 range of 10–50◦ . Fig. 4 shows the indexed powder XRD pattern and the XRD profiles show that the sample is of single phase without detectable impurity. The well defined Bragg’s peaks at specific 2 angles show high crystallinity of the material. 3.4. SEM The surface morphology of the as-grown crystals was observed by using a JEOL JSM 5610 LV scanning electron microscope with a resolution of 3.0 nm and accelerating voltage 20 kV. The SEM micrographs with different magnifications of the as-grown DPMI
Fig. 1. Photographs of as-grown DPMI crystals.
% Transmiance
60
40
20
0 200
400
600
800
Wavelength (nm) Fig. 2. FT-IR spectrum of DPMI.
Fig. 3. UV–vis spectrum of DPMI (Tauc plot is given as inset).
V. Meenatchi et al. / Optik 125 (2014) 4181–4185
Fig. 4. Powder XRD pattern of DPMI.
are shown in Fig. 5. Dentric growth morphology is observed on the surface with a lot of imperfections and crystal voids. 3.5. Thermal analysis The TG/DTA analysis of DPMI was carried out using NETZSCH STA 449F3 thermal analyzer in nitrogen atmosphere. In the TG curve trace there is a single major weight loss starting at ∼300 ◦ C. The decomposition is completed at ∼400 ◦ C, leaving no residue and it could be due to decomposition of DPMI. In the DTA a sharp endothermic peak at ∼135 ◦ C is due to the melting point of the material and it was confirmed by using Sigma instrument melting point apparatus (133–134 ◦ C). The sharpness of the peak shows good degree of crystallinity and purity of crystal. 3.6. Single crystal XRD The structural analysis of DPMI was carried out for a selected needle of approximately 0.30 mm × 0.20 mm × 0.20 mm using Bruker AXS (Kappa APEXII) X-ray diffractometer with Mo K˛ radi˚ The single crystal X-ray diffraction analysis ation ( = 0.71073 A). shows that the DPMI belongs to triclinic system with centrosym˚ metric space group P 1¯ and the cell parameters are, a = 8.679(5) A,
4183
Fig. 6. ORTEP diagram of DPMI.
˚ ˚ b = 9.753(5) A, c = 11.007(5) A, ˛ = 75.809(5)◦ , ˇ = 74.846(5)◦ , = 87.089(5)◦ , V = 871.8(8) A˚ 3 and Z = 1. The ORTEP diagram is given in Fig. 6 and the crystal data are given in Table 1. The O1 atom and the hydrazinic N3 atom are cis with respect to C6 N2 bond. The structure of the compound reveals the quasi coplanarity of the whole molecular skeleton with localization of the double bonds in the central C N N C O which has an Econfiguration with respect to the double bond of the hydrazone bridge. A trans configuration is fixed around the N3 N2 single bond ˚ The angle O1 C6 N2 (124.0(11)◦ ) is greater of length 1.37(3) A. than O1 C6 C5 (120.42(13)◦ ) possibly in order to relive repulsion between lone pair of electrons on the atoms N3 and O1. The central part of the molecule C7 N3 N2 C6 O1, adopts a completely ˚ extended conformation. The bond lengths C7 N3 (1.2870(18) A) ˚ are typical of double bonds. In the and C6 O1 (1.2172(17) A) crystal structure, molecules are linked through intermolecular N H· · ·O, O H· · ·N and O H· · ·O hydrogen bonds involving the water molecule. 3.7. HRXRD To reveal the crystalline perfection of the specimen crystals, high-resolution X-ray diffraction (HRXRD) analysis was carried out. Table 1 Crystal data and structure refinement for DPMI. Identification code Empirical formula Formula weight Temperature Wavelength Crystal system, space group Unit cell dimensions
Volume Z, calculated density Absorption coefficient F(0 0 0) Crystal size Theta range for data collection Limiting indices
Fig. 5. SEM images of DPMI.
Reflections collected/unique Completeness to theta = 25.00 Absorption correction Max. and min. transmission Refinement method Data/restraints/parameters Goodness-of-fit on F2ˆ Final R indices [I > 2 sigma (I)] R indices (all data) Extinction coefficient Largest diff. peak and hole
shelxl C38 H38 N6 O6 674.74 293(2) K 0.71073 A˚ Triclinic, P1¯ ˚ ˛ = 75.809(5)◦ a = 8.679(5) A, ˚ ˇ = 74.846(5)◦ b = 9.753(5) A, ˚ = 87.089(5)◦ c = 11.007(5) A, 871.8(8) A˚ 3 1, 1.285 Mg/m3 0.089 mm−1 356 0.30 × 0.20 × 0.20 mm3 1.97–25.00◦ −10 ≤ h ≤ 10, −11 ≤ k ≤ 11, −13 ≤ l ≤ 13 14938/3065 [R(int) = 0.0240] 100.0% Semi-empirical from equivalents 0.9973 and 0.9534 Full-matrix least-squares on F2 3065/20/261 1.030 R1 = 0.0399, wR2 = 0.1123 R1 = 0.0495, wR2 = 0.1219 0.039(5) 0.188 and −0.1137 eA˚ −3
4184
V. Meenatchi et al. / Optik 125 (2014) 4181–4185 Table 2 The calculated dipole moment (in D), ˇ components and ˇtot (in esu) values of DPMI.
Fig. 7. HRXRD curves of DPMI.
A multicrystal X-ray diffractometer developed at NPL was used to record high resolution diffraction curves (DCs). In this system, a fine focus (0.4 mm × 8 mm; 2 kW Mo) X-ray source energized by a well-stabilized Philips X-ray generator (PW 1743) is employed. The well collimated and monochromated Mo K˛1 beam obtained from the three monochromator Si crystals set in dispersive (+, −, −) configuration is used as the exploring X-ray beam. This arrangement improves the spectral purity (/ 10−5 ) of the Mo K˛1 beam. The divergence of the exploring beam in the horizontal plane (plane of diffraction) is estimated to be 3 . The specimen crystal is aligned in the (+, −, −, +) configuration. The specimen can be rotated about a vertical axis, which is perpendicular to the plane of diffraction, with minimum angular interval of 0.4 . The diffracted intensity is measured by using a scintillation counter. The high resolution X-ray diffraction curve (Fig. 7) recorded for (1 1 1) diffraction planes using Mo K˛1 radiation for a typical DPMI single crystal specimen. The curve is not a single peak and on deconvolution of the diffraction curve, it is clear that it contains three additional peaks. The solid line (convoluted curve) is well fitted with the experimental points represented by the filled circles, which are 130 , 47 and 108 away from the main peak (highest intensity peak). These two additional peaks correspond to two internal structural low angle boundaries (tilt angle >1 but <1◦ ) boundaries [10] whose tilt angles (Tilt angle may be defined as the misorientation angle between the two crystalline regions on both sides of the structural grain boundary) are 130 , 47 and 108 from their adjoining regions. The FWHM (full width at half maximum) of the main peak and the three low angle boundaries are respectively 28 and 38 , 70 and 76 . The relatively low values of FWHM of the grains and low angular spread of the DC (∼1000 = ∼17 ) depicts that the crystalline perfection is moderate.
ˇxxx ˇxxy ˇxyy ˇyyy ˇxxz ˇxyz ˇyyz ˇxzz ˇyxx ˇzzz ˇtot (x10 −30 ) x y z
−114.419 −44.299 −68.025 37.907 20.598 9.585 22.725 2.079 20.436 25.688 1.673 1.597 6.768 4.270 8.161
Fig. 8. Optimized molecular structure of DPMI.
4. Conclusions Transparent bulk crystals of DPMI were grown in ethanol by the slow evaporation solution growth technique at room temperature. The product formation was confirmed by FT-IR and single crystal XRD analyses. The crystallographic data indicate that the DPMI crystallizes in triclinic system with centrosymmetric space group P 1¯ while the precursor benzophenone belongs to orthorhombic system with noncentrosymmetric space group P21 21 21 . The powder X-ray diffraction study shows the good crystallinity of the material. TG/DTA study reveals the purity of the sample and no decomposition is observed up to the melting point. Good transmission in the visible region is observed and the band gap energy is estimated as 3.14 eV, using the reflectance data. HRXRD studies reveal a low-angle structural grain boundary with a moderate crystalline perfection. Molecular level nonlinearity with a high first-order molecular hyperpolarizability is observed.
3.8. Theoretical studies Acknowledgments Hartree–Fock calculations was performed using the GAUSSIAN 03W [11] program package on a personal computer without any constraints on the geometry, using Hartree–Fock method with 631G (d,p) as the basis set [12]. By the use of the GAUSSVIEW 5.0 molecular visualization program [13] the optimized structure of the molecule has been visualized. The calculated polarizability (˛), first-order molecular hyperpolarizability (ˇ) and dipole moment () of the specimen are 31.748 × 10−24 esu, 1.673 × 10−30 esu (∼5 times of urea), 8.1606 D respectively (Table 2). The maximum ˇ is due to the behavior of nonzero values. The optimized molecular structure of DPMI (Fig. 8) closely resembles the displacement ellipsoid diagram (Fig. 6). NLO depends on the structure and orientation. In the present study, microscopic ˇ is large but the bulk second-order nonlinearity is zero due to the cancelation of charge transfer in a centrosymmetric environment.
The authors thank the Council of Scientific and Industrial Research(CSIR), New Delhi, for financial support through research grant No.03(1233)/12/EMR–II, and VM is grateful to CSIR project for the award of Senior Research Fellowship (SRF). KM is thankful to CSIR, New Delhi, for the award of SRF. References [1] M. Gallego, M. García-Vargas, M. Valcarcel, Pyridine-2-carbaldehyde 2hydroxybenzoylhydrazone as a selective reagent for the extraction and spectrophotometric determination of iron (II), Analyst 104 (1979) 613–619. [2] M. Gallego, M. Garcı a-Vargas, F. Pino, M. Valcarcel, Analytical applications of picolinealdehyde salicyloylhydrazone: spectrophotometric determination of nickel and zinc, Microchem. J. 23 (1978) 353–359. [3] M.E. Lizarraga, R. Navarro, E.P. Urriolabeitia, Synthesis and characterization of dinuclear complexes of PdII containing the ( N C S)2 skeleton, J. Org. Met. Chem. 542 (1997) 51–60.
V. Meenatchi et al. / Optik 125 (2014) 4181–4185 [4] A.S. Georgopoulou, S. Ulvenlund, D.M.P. Mingos, I. Baxter, D.J. Williams, Synthesis of water soluble DTPA complexes with pendant uracil moieties capable of forming complementary hydrogen bonds, J. Chem. Soc. 4 (1999) 547–552. [5] W. Liaw, N. Lee, C. Chen, C. Lee, G. Lee, S. Peng, Dinuclear and mononuclear iron(II)-thiolate complexes with mixed CO/CN− ligands: synthetic advances for iron sites of [Fe]-only hydrogenases, J. Am. Chem. Soc. 122 (2000) 488–494. [6] P.J. Trotter, P.A. White, Resonance Raman determination of the triiodide structure in bis(tetrathiotetracene)triiodide organic conductor compared with the poly(vinyl alcohol)-iodine complex, J. Appl. Spectrosc. 323 (1978) 23–324. [7] K.Y. Rajpure, C.H. Bhosale, Sb2 S3 semiconductor-septum rechargeable storage cell, J. Mater. Chem. Phys. 64 (2000) 70–74.
4185
[8] S. Licht, Electrolyte modified photoelectrochemical solar cells, Sol. Energy Mater. Sol. Cells 38 (1995) 305–319. [9] A.P. Kubelka, New contributions to the optics of intensely light scattering materials, J. Opt. Soc. Am. 38 (1948) 448–457. [10] G. Bhagavannarayana, R.V. Ananthamurthy, G.C. Budakoti, B. Kumar, K.S. Bartwal, A study of the effect of annealing on Fe-doped LiNbO3 by HRXRD, XRT and FT-IR, J. Appl. Cryst. 38 (2005) 768–771. [11] M.J. Frisch, G.W. Trucks, et al., Gaussian03, Gaussian Inc., Wallingford, CT, USA, 2004. [12] B. Schlegel, Optimization of equilibrium geometries and transition structures, J. Comput. Chem. 3 (1982) 214–218. [13] A. Frisch, A.B. Nielson, A.J. Holder, GAUSSVIEW User Manual, Gaussian Inc., Pittsburgh, PA, 2000.
Contents lists available at ScienceDirect
Optik journal homepage: www.elsevier.de/ijleo
Synthesis, growth, structure, spectral, crystalline perfection and theoretical studies on (E)-N -(diphenylmethylene)isonicotinohydrazide dihydrate crystals V. Meenatchi a , K. Muthu a , M. Rajasekar a , G. Bhagavannarayana b , SP. Meenakshisundaram a,∗ a b
Department of Chemistry, Annamalai University, Annamalainagar 608 002, Tamilnadu, India National Physical Laboratory, New Delhi 110012, India
a r t i c l e
i n f o
a b s t r a c t
Article history: Received 19 July 2013 Accepted 13 January 2014
Single crystals of (E)-N -(diphenylmethylene)isonicotinohydrazide dihydrate have been grown by slow evaporation solution growth technique from ethanol at room temperature. The crystal belongs to triclinic ˚ b = 9.753(5) A, ˚ c = 11.007(5) A˚ system with the space group P 1¯ and the cell parameters are, a = 8.679(5) A, and V = 871.8(8) A˚ 3 . The functional groups present in the molecule are confirmed by Fourier transform
Keywords: Crystal structure Infrared spectroscopy UV–vis spectroscopy Theoretical calculation Hyperpolarizability
infrared spectroscopy and crystallinity by XRD. The crystals are transparent in the visible region and have a lower optical cut-off at ∼410 nm with a band gap energy of 3.14 eV, estimated by the application of Kubelka–Munk algorithm. The crystalline perfection as evaluated by high-resolution X-ray diffraction analysis reveals multi peaks. Theoretical calculations were performed using Hartree–Fock method with 6-31G(d,p) as the basis set for to derive the optimized geometry, dipole moment and first-order molecular hyperpolarizality (ˇ) values. © 2014 Elsevier GmbH. All rights reserved.
1. Introduction Organic single crystals possess unique optoelectronic properties because the molecules have delocalized electrons, namely, conjugated electron systems exhibiting various photoresponses such as photoconductive, photovoltaic, photocatalytic behavior and so on. The organic materials with intramolecular charge transfer compounds have large second-order nonlinear optical effects. Electron rich (donor) and deficient (acceptor) substituents provide the asymmetric charge distribution in the electron system, show large nonlinear optical responses. The chemistry of Schiff bases has been intensively investigated in recent years owing to their co-ordination properties and diverse applications. Schiff base hydrazones are widely used in analytical chemistry as selective metal extracting agents as well as in spectroscopic determination of certain transition metals [1,2]. The development of the field of bioinorganic chemistry has increased the interest in Schiff base complexes since it has been recognized that many of these complexes may serve as models for biologically important
∗ Corresponding author. Tel.: +91 4144 221670. E-mail addresses: [email protected], [email protected] (SP. Meenakshisundaram). http://dx.doi.org/10.1016/j.ijleo.2014.05.006 0030-4026/© 2014 Elsevier GmbH. All rights reserved.
species. Pyridine heterocycles are repeated moieties in many large molecules with interesting photophysical, electrochemical and catalytic applications [3–8]. The growth, structure and characterization of (E)-N -(diphenylmethylene)isonicotinohydrazide dihydrate (DPMI) have not been reported so far to the best of our knowledge. In the present study, we report the synthesis, growth, structure, dipole moment, hyperpolarizability and characterization of a new organic crystal, isonicotinohydrazide.
2. Experimental 2.1. Synthesis and crystal growth dihydrate (E)-N -(diphenylmethylene)isonicotinohydrazide (DPMI) was synthesized by mixing stoichiometric amounts of benzophenone and isoniazid in the molar ratio of 1:1. The reactants were dissolved in ethanolic medium with catalytic amount of concentrated sulphuric acid and refluxed for 3–5 h to form aryl acid hydrazone. The completion of the reaction was confirmed by thin layer chromatography. The reaction mixture was then poured in ice cold water and the precipitate obtained was filtered and dried. Purity of the compound was improved by recrystallization process using ethanol as a solvent.
4182
V. Meenatchi et al. / Optik 125 (2014) 4181–4185
N
O
O
C
NH NH2
C
C c on.H 2 S O 4
N
N
H
peaks around 1056 and 754 cm−1 are due to N N and aromatic C H out of plane bending vibrations respectively. 3.2. Optical studies The optical transmission spectrum of DPMI was recorded using 5E UV–vis spectrophotometer. The optical transmission spectrum (Fig. 3) shows the absorption is minimum in the visible region and cut-off wavelength is ∼ 410 nm. The Kubelka–Munk theory [9] provides a correlation between reflectance and concentration. The concentration of an absorbing species can be determined using the Kubelka–Munk formula,
3. Results and discussion F(R) =
3.1. FT-IR The FT-IR spectrum was recorded for DPMI crystal using an AVATAR 330 FT-IR by KBr pellet technique in the spectral range of 400–4000 cm−1 (Fig. 2). The absorption band at 1699 cm−1 is due to C O stretching vibration. The absorption band around 3254 cm−1 is due to N H stretching frequency. The C N stretching frequency appeared as sharp intensity band around 1639 cm−1 . An absorption band in the region 3000–3100 cm−1 is due to C H stretching frequency of aromatic ring. The band at 1498 cm−1 is due to C C stretching frequency of aromatic region. The absorption band around 1118 cm−1 is due to O C N stretching vibrations. The
N C
E th ano l
DPMI single crystals were grown using slow evaporation solution growth technique at room temperature. A saturated solution of DPMI in ethanol was prepared and the solution was stirred for 2–3 h at room temperature to obtain a homogenous solution. A beaker containing DPMI solution was tightly covered with a thin polythene sheet to control the evaporation rate of the solvent and kept undisturbed in a dust free environment. Numerous tiny crystals were formed at the bottom of the container due to spontaneous nucleation. Macroscopic defect-free crystals of DPMI were harvested after 9–11 days and the photographs of as-grown crystals are shown in Fig. 1.
O
(1 − R)2 a Ac = = 2R s s
where F(R) is Kubelka–Munk fuction, R is the reflectance of the crystal and s is scattering coefficient, A is the absorbance and c is concentration of the absorbing species. The measurement of [F(R)hv] as a function of hv provides the band gap energy Eg of the material. The direct band gap energy can be obtained from the intercept of the resulting straight lines with the energy axis at [F(R)hv]2 = 0 and the band gap energy of the specimen is deduced as 3.14 eV. The Tauc plot is given as inset in Fig. 3. 3.3. Powder XRD As-grown DPMI crystal was finely powdered and subjected to powder XRD analysis using a Philips X’pert pro Triple-axis X-ray diffractometer at room temperature using a wavelength of 1.540 A˚ and a step size of 0.008◦ . The samples were examined with CuK␣ radiation in 2 range of 10–50◦ . Fig. 4 shows the indexed powder XRD pattern and the XRD profiles show that the sample is of single phase without detectable impurity. The well defined Bragg’s peaks at specific 2 angles show high crystallinity of the material. 3.4. SEM The surface morphology of the as-grown crystals was observed by using a JEOL JSM 5610 LV scanning electron microscope with a resolution of 3.0 nm and accelerating voltage 20 kV. The SEM micrographs with different magnifications of the as-grown DPMI
Fig. 1. Photographs of as-grown DPMI crystals.
% Transmiance
60
40
20
0 200
400
600
800
Wavelength (nm) Fig. 2. FT-IR spectrum of DPMI.
Fig. 3. UV–vis spectrum of DPMI (Tauc plot is given as inset).
V. Meenatchi et al. / Optik 125 (2014) 4181–4185
Fig. 4. Powder XRD pattern of DPMI.
are shown in Fig. 5. Dentric growth morphology is observed on the surface with a lot of imperfections and crystal voids. 3.5. Thermal analysis The TG/DTA analysis of DPMI was carried out using NETZSCH STA 449F3 thermal analyzer in nitrogen atmosphere. In the TG curve trace there is a single major weight loss starting at ∼300 ◦ C. The decomposition is completed at ∼400 ◦ C, leaving no residue and it could be due to decomposition of DPMI. In the DTA a sharp endothermic peak at ∼135 ◦ C is due to the melting point of the material and it was confirmed by using Sigma instrument melting point apparatus (133–134 ◦ C). The sharpness of the peak shows good degree of crystallinity and purity of crystal. 3.6. Single crystal XRD The structural analysis of DPMI was carried out for a selected needle of approximately 0.30 mm × 0.20 mm × 0.20 mm using Bruker AXS (Kappa APEXII) X-ray diffractometer with Mo K˛ radi˚ The single crystal X-ray diffraction analysis ation ( = 0.71073 A). shows that the DPMI belongs to triclinic system with centrosym˚ metric space group P 1¯ and the cell parameters are, a = 8.679(5) A,
4183
Fig. 6. ORTEP diagram of DPMI.
˚ ˚ b = 9.753(5) A, c = 11.007(5) A, ˛ = 75.809(5)◦ , ˇ = 74.846(5)◦ , = 87.089(5)◦ , V = 871.8(8) A˚ 3 and Z = 1. The ORTEP diagram is given in Fig. 6 and the crystal data are given in Table 1. The O1 atom and the hydrazinic N3 atom are cis with respect to C6 N2 bond. The structure of the compound reveals the quasi coplanarity of the whole molecular skeleton with localization of the double bonds in the central C N N C O which has an Econfiguration with respect to the double bond of the hydrazone bridge. A trans configuration is fixed around the N3 N2 single bond ˚ The angle O1 C6 N2 (124.0(11)◦ ) is greater of length 1.37(3) A. than O1 C6 C5 (120.42(13)◦ ) possibly in order to relive repulsion between lone pair of electrons on the atoms N3 and O1. The central part of the molecule C7 N3 N2 C6 O1, adopts a completely ˚ extended conformation. The bond lengths C7 N3 (1.2870(18) A) ˚ are typical of double bonds. In the and C6 O1 (1.2172(17) A) crystal structure, molecules are linked through intermolecular N H· · ·O, O H· · ·N and O H· · ·O hydrogen bonds involving the water molecule. 3.7. HRXRD To reveal the crystalline perfection of the specimen crystals, high-resolution X-ray diffraction (HRXRD) analysis was carried out. Table 1 Crystal data and structure refinement for DPMI. Identification code Empirical formula Formula weight Temperature Wavelength Crystal system, space group Unit cell dimensions
Volume Z, calculated density Absorption coefficient F(0 0 0) Crystal size Theta range for data collection Limiting indices
Fig. 5. SEM images of DPMI.
Reflections collected/unique Completeness to theta = 25.00 Absorption correction Max. and min. transmission Refinement method Data/restraints/parameters Goodness-of-fit on F2ˆ Final R indices [I > 2 sigma (I)] R indices (all data) Extinction coefficient Largest diff. peak and hole
shelxl C38 H38 N6 O6 674.74 293(2) K 0.71073 A˚ Triclinic, P1¯ ˚ ˛ = 75.809(5)◦ a = 8.679(5) A, ˚ ˇ = 74.846(5)◦ b = 9.753(5) A, ˚ = 87.089(5)◦ c = 11.007(5) A, 871.8(8) A˚ 3 1, 1.285 Mg/m3 0.089 mm−1 356 0.30 × 0.20 × 0.20 mm3 1.97–25.00◦ −10 ≤ h ≤ 10, −11 ≤ k ≤ 11, −13 ≤ l ≤ 13 14938/3065 [R(int) = 0.0240] 100.0% Semi-empirical from equivalents 0.9973 and 0.9534 Full-matrix least-squares on F2 3065/20/261 1.030 R1 = 0.0399, wR2 = 0.1123 R1 = 0.0495, wR2 = 0.1219 0.039(5) 0.188 and −0.1137 eA˚ −3
4184
V. Meenatchi et al. / Optik 125 (2014) 4181–4185 Table 2 The calculated dipole moment (in D), ˇ components and ˇtot (in esu) values of DPMI.
Fig. 7. HRXRD curves of DPMI.
A multicrystal X-ray diffractometer developed at NPL was used to record high resolution diffraction curves (DCs). In this system, a fine focus (0.4 mm × 8 mm; 2 kW Mo) X-ray source energized by a well-stabilized Philips X-ray generator (PW 1743) is employed. The well collimated and monochromated Mo K˛1 beam obtained from the three monochromator Si crystals set in dispersive (+, −, −) configuration is used as the exploring X-ray beam. This arrangement improves the spectral purity (/ 10−5 ) of the Mo K˛1 beam. The divergence of the exploring beam in the horizontal plane (plane of diffraction) is estimated to be 3 . The specimen crystal is aligned in the (+, −, −, +) configuration. The specimen can be rotated about a vertical axis, which is perpendicular to the plane of diffraction, with minimum angular interval of 0.4 . The diffracted intensity is measured by using a scintillation counter. The high resolution X-ray diffraction curve (Fig. 7) recorded for (1 1 1) diffraction planes using Mo K˛1 radiation for a typical DPMI single crystal specimen. The curve is not a single peak and on deconvolution of the diffraction curve, it is clear that it contains three additional peaks. The solid line (convoluted curve) is well fitted with the experimental points represented by the filled circles, which are 130 , 47 and 108 away from the main peak (highest intensity peak). These two additional peaks correspond to two internal structural low angle boundaries (tilt angle >1 but <1◦ ) boundaries [10] whose tilt angles (Tilt angle may be defined as the misorientation angle between the two crystalline regions on both sides of the structural grain boundary) are 130 , 47 and 108 from their adjoining regions. The FWHM (full width at half maximum) of the main peak and the three low angle boundaries are respectively 28 and 38 , 70 and 76 . The relatively low values of FWHM of the grains and low angular spread of the DC (∼1000 = ∼17 ) depicts that the crystalline perfection is moderate.
ˇxxx ˇxxy ˇxyy ˇyyy ˇxxz ˇxyz ˇyyz ˇxzz ˇyxx ˇzzz ˇtot (x10 −30 ) x y z
−114.419 −44.299 −68.025 37.907 20.598 9.585 22.725 2.079 20.436 25.688 1.673 1.597 6.768 4.270 8.161
Fig. 8. Optimized molecular structure of DPMI.
4. Conclusions Transparent bulk crystals of DPMI were grown in ethanol by the slow evaporation solution growth technique at room temperature. The product formation was confirmed by FT-IR and single crystal XRD analyses. The crystallographic data indicate that the DPMI crystallizes in triclinic system with centrosymmetric space group P 1¯ while the precursor benzophenone belongs to orthorhombic system with noncentrosymmetric space group P21 21 21 . The powder X-ray diffraction study shows the good crystallinity of the material. TG/DTA study reveals the purity of the sample and no decomposition is observed up to the melting point. Good transmission in the visible region is observed and the band gap energy is estimated as 3.14 eV, using the reflectance data. HRXRD studies reveal a low-angle structural grain boundary with a moderate crystalline perfection. Molecular level nonlinearity with a high first-order molecular hyperpolarizability is observed.
3.8. Theoretical studies Acknowledgments Hartree–Fock calculations was performed using the GAUSSIAN 03W [11] program package on a personal computer without any constraints on the geometry, using Hartree–Fock method with 631G (d,p) as the basis set [12]. By the use of the GAUSSVIEW 5.0 molecular visualization program [13] the optimized structure of the molecule has been visualized. The calculated polarizability (˛), first-order molecular hyperpolarizability (ˇ) and dipole moment () of the specimen are 31.748 × 10−24 esu, 1.673 × 10−30 esu (∼5 times of urea), 8.1606 D respectively (Table 2). The maximum ˇ is due to the behavior of nonzero values. The optimized molecular structure of DPMI (Fig. 8) closely resembles the displacement ellipsoid diagram (Fig. 6). NLO depends on the structure and orientation. In the present study, microscopic ˇ is large but the bulk second-order nonlinearity is zero due to the cancelation of charge transfer in a centrosymmetric environment.
The authors thank the Council of Scientific and Industrial Research(CSIR), New Delhi, for financial support through research grant No.03(1233)/12/EMR–II, and VM is grateful to CSIR project for the award of Senior Research Fellowship (SRF). KM is thankful to CSIR, New Delhi, for the award of SRF. References [1] M. Gallego, M. García-Vargas, M. Valcarcel, Pyridine-2-carbaldehyde 2hydroxybenzoylhydrazone as a selective reagent for the extraction and spectrophotometric determination of iron (II), Analyst 104 (1979) 613–619. [2] M. Gallego, M. Garcı a-Vargas, F. Pino, M. Valcarcel, Analytical applications of picolinealdehyde salicyloylhydrazone: spectrophotometric determination of nickel and zinc, Microchem. J. 23 (1978) 353–359. [3] M.E. Lizarraga, R. Navarro, E.P. Urriolabeitia, Synthesis and characterization of dinuclear complexes of PdII containing the ( N C S)2 skeleton, J. Org. Met. Chem. 542 (1997) 51–60.
V. Meenatchi et al. / Optik 125 (2014) 4181–4185 [4] A.S. Georgopoulou, S. Ulvenlund, D.M.P. Mingos, I. Baxter, D.J. Williams, Synthesis of water soluble DTPA complexes with pendant uracil moieties capable of forming complementary hydrogen bonds, J. Chem. Soc. 4 (1999) 547–552. [5] W. Liaw, N. Lee, C. Chen, C. Lee, G. Lee, S. Peng, Dinuclear and mononuclear iron(II)-thiolate complexes with mixed CO/CN− ligands: synthetic advances for iron sites of [Fe]-only hydrogenases, J. Am. Chem. Soc. 122 (2000) 488–494. [6] P.J. Trotter, P.A. White, Resonance Raman determination of the triiodide structure in bis(tetrathiotetracene)triiodide organic conductor compared with the poly(vinyl alcohol)-iodine complex, J. Appl. Spectrosc. 323 (1978) 23–324. [7] K.Y. Rajpure, C.H. Bhosale, Sb2 S3 semiconductor-septum rechargeable storage cell, J. Mater. Chem. Phys. 64 (2000) 70–74.
4185
[8] S. Licht, Electrolyte modified photoelectrochemical solar cells, Sol. Energy Mater. Sol. Cells 38 (1995) 305–319. [9] A.P. Kubelka, New contributions to the optics of intensely light scattering materials, J. Opt. Soc. Am. 38 (1948) 448–457. [10] G. Bhagavannarayana, R.V. Ananthamurthy, G.C. Budakoti, B. Kumar, K.S. Bartwal, A study of the effect of annealing on Fe-doped LiNbO3 by HRXRD, XRT and FT-IR, J. Appl. Cryst. 38 (2005) 768–771. [11] M.J. Frisch, G.W. Trucks, et al., Gaussian03, Gaussian Inc., Wallingford, CT, USA, 2004. [12] B. Schlegel, Optimization of equilibrium geometries and transition structures, J. Comput. Chem. 3 (1982) 214–218. [13] A. Frisch, A.B. Nielson, A.J. Holder, GAUSSVIEW User Manual, Gaussian Inc., Pittsburgh, PA, 2000.