Synthesis, crystal structure, physicochemical properties of hydrogen bonded supramolecular assembly of N,N-diethylanilinium-3, 5-dinitrosalicylate crystal

Accepted Manuscript Synthesis, crystal structure, physicochemical properties of hydrogen bonded supramolecular assembly of N,N-diethylanilinium-3, 5-dinitrosalicylate crystal

M. Rajkumar, A. Chandramohan PII:

S0022-2860(17)31087-6

DOI:

10.1016/j.molstruc.2017.08.021

Reference:

MOLSTR 24159

To appear in:

Journal of Molecular Structure

Received Date:

09 March 2017

Revised Date:

23 June 2017

Accepted Date:

07 August 2017

Please cite this article as: M. Rajkumar, A. Chandramohan, Synthesis, crystal structure, physicochemical properties of hydrogen bonded supramolecular assembly of N,N-diethylanilinium3, 5-dinitrosalicylate crystal, Journal of Molecular Structure (2017), doi: 10.1016/j.molstruc. 2017.08.021

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ACCEPTED MANUSCRIPT Graphical abstract

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Synthesis, crystal structure, physicochemical properties of hydrogen bonded supramolecular assembly of N,N-diethylanilinium-3, 5-dinitrosalicylate crystal M. Rajkumar, A. Chandramohan* Post-Graduate and Research Department of Chemistry, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore - 641 020, Tamil Nadu, India. Abstract An organic salt, N,N-diethylanilinium 3,5-dinitrosalicylate was synthesized and single crystals grown by employing the slow solvent evaporation solution growth technique in methanol- acetone (1:1) mixture. The electronic transitions of the salt crystal were studied by UV-Visible spectrum. The optical transmittance window and lower wavelength cut-off of grown crystal have been identified by UV-Vis-NIR studies. The FT-IR spectrum was recorded to confirm the presence of various functional groups in the grown crystal. 1H and 13C

NMR spectrum were recorded to establish the molecular structure of the title crystal.

Single crystal X-ray diffraction data indicated that the crystal belongs to monoclinic crystal system with P21/n space group. The thermal stability of the crystal was established by TG/DTA studies. The mechanical properties of the grown crystal were studied by Vickers' microhardness technique. The dielectric studies indicated that the dielectric constant and dielectric loss decrease exponentially with frequency at different temperatures. Keywords: Crystal growth, Single crystal XRD, Crystal structure, Electrical properties, Thermal studies, Mechanical properties

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*Corresponding author.Tel.: +919994283655. E-mail address: [email protected] (A. Chandramohan) 1. Introduction Organic materials are distinct owing to their optical and electronic properties and tunable through structural modifications [1]. Single crystals are significantly used in the field of electronics and optics [2]. Organic single crystals play a crucial role because of their fast and large nonlinear response over a broad frequency range, high optical damage threshold and intrinsic tailorability [3]. Normally, slow solvent evaporation solution growth technique is adopted for the growth of single crystal due to the fact that the suitability, simplicity and the possible avoidance of complex growth of crystal [4, 5]. Many new organic crystals have been found because of their predictive molecular engineering approach and have been shown to have potential applications in nonlinear optics and these materials find wide range of applications in optical parametric oscillation, frequency mixing, optical bi-stability, and optical image processing, under water communication, optical data storage, electro-optical shutters, color displays, optical communications and signal processing. [6,7]. Moreover, it is necessary to increase the number of π-electrons and π-electrons delocalization length to achieve good macroscopic nonlinear response in organic crystals, so as to lead to high molecular hyperpolarizability and also proper orientation of the molecule in the solid state structure to facilitate high-frequency conversion efficiency [8]. Hence, organic derivatives having π-electrons spread over a large distance with various combinations of terminal electron donor and acceptor groups have been the objective of recent research, particularly due to their large molecular hyperpolarizabilities and good crystallizability [9-13].

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Intermolecular interactions are responsible for crystal packing and permit the design of new crystals with specific physical and chemical properties [14]. Hydrogen bonding is one of the important types of non-covalent interactions in many organic and inorganic species, which results in aggregation and controls self-assembly [15-18]. The intermolecular hydrogen bonding enhances the mechanical and thermal stability of the crystal [19, 20]. Recently, the carboxylic acids have been utilized as important substrate for synthesis because of their ability to generate predictable supramolecular modes with the hydrogen-bonding interactions among themselves [21, 22]. 3, 5-Dintro salicylic acid (DNSA) is especially attractive acid, possessing three potential functional groups such as NO2, OH and COOH. Based on these aspects, in this paper we present the synthesis, growth, spectroscopic and structural characterization of organic hydrogen bonding salt N-Diethylanilinium3, 5dinitrosalicylate (DASA). The title material was synthesized, grown as a single crystal and characterized through UV-visible, UV-Vis-NIR, FT-IR, NMR spectral studies, single crystal XRD analysis, TG–DTA analyses, dielectric and Micro hardness studies. On the basis of the above studies, the molecular structure, intermolecular interactions, optical, thermal, mechanical and electrical properties of the title complex have been reported. 2. Experimental procedure 2. 1. Material synthesis and growth of Single Crystal AR grade N, N-diethylailine and 3, 5-dintro salicylic acid were purchased and used as such without further purification. The 1:1 molar ratio of N, N-diethylailine and 3, 5-dintro salicylic acid were dissolved in methanol separately. The two solutions were henceforth mixed together and stirred well for about 30 minutes using magnetic stirrer at room

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temperature. A pale yellow precipitate of the salt via, N, N-diethylanilinium3, 5dinitrosalicylate (DASA) was obtained immediately. The reaction involved in the synthesis of DASA salt is represented in the Fig.1. 2.2. Growth of Single Crystal A saturated solution of the title salt was prepared in methanol- acetone (1:1) mixture, stirred well for about 30 minutes and heated slightly to dissolve all the undissolved substance. Then the solution was filtered through a Whatmann 41 grade filter paper to remove the suspended impurities. The clear filtrate was collected in a 250 ml beaker and kept aside unperturbed in a dust free room for the growth of single crystals of the title compound. Well grown yellow coloured and transparent single crystals were harvested at the end of fourteenth day. The photograph as -grown title crystal is shown in Fig. 2. 2.3. Characterization techniques UV- Visible spectrum was recorded employing a SYSTRONICS make Double Beam Spectrophotometer 2202 in the range from 200 to 1000nm using methanol as solvent. The UV-vis-NIR transmittance Spectrum of the DASA crystal was recorded using JASCO UV-Vis-NIR Spectrophotometer in the range 200-1500 nm. The FT-IR spectrum of DASA crystal was recorded employing a Perkin Elmer FT-IR Spectrometer using KBr pellet technique in the range 4000–400 cm-1. 1H and 13C NMR spectrum were recorded employing a Bruker 500 MHz Spectrometer in MeOH-d4 using TMS as the internal reference standard. The crystal structure was determined from the Single-Crystal X-ray diffraction data obtained with a X’calibur CCD area-detector diffractometer (Graphite-monochromated, Mo Kα =0.71073). The structure was solved by direct methods [23] using the program SHELXS-97

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and refined by full-matrix least-squares method using the program SHELXL-97 [24]. The TG and DTA analyses were carried out simultaneously employing ‘S11 Nanotechnology Thermal Analyzer’ instrument at a heating rate of 20°C per minute in nitrogen atmosphere. The Microhardness studies have been carried out on the DASA single crystal using HMV SHIMADZU tester, fitted with diamond Vickers pyramidal indenter. Dielectric studies for the grown crystals were carried out in the frequency range from 50 Hz to 5 MHz at different temperatures using Hioki LCR 3532-50 LCR meter. 3. Results and Discussion 3.1. UV-Visible Spectral Studies The UV-Visible spectrum of DASA gives the information about the structure of the molecule, because the absorption of UV and visible light involves promotion of the electron in the n and π orbital from ground state to excited states [25] and the spectrum is shown in the Fig.3. The spectrum exhibits strong absorption bands attributed to two π-π* transitions in the near UV-region of the spectrum. The π-π* transitions of N, N Dimethylaniliniun3, 5dinitrosalicylate appear at 261 and 366 nm [26]. From the spectrum, it is noted that there after no significant absorption has been noticed in the visible region above 430 nm. It is an important requirement for NLO materials having nonlinear optical applications. 3.2. UV-Vis-NIR Spectral Studies The UV-Vis-NIR transmittance spectrum of the title crystal was recorded in the wavelength range 200-1500 nm using powered sample of the crystal and the recorded spectrum depicted in Fig.4. The attained percentage of transmittance is about 85 % in the

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visible region. As has been observed from the spectrum, there is no significant absorption in the entire visible region and infrared region. Hence the crystal is transparent between 3001500 nm. The lower wavelength cut-off is around 310 nm. At longer wavelength side, the crystal is transparent up to 1500 nm. It is an important requirement for various optical applications. The optical absorption coefficient (α) was calculated using the recorded transmittance spectrum by the given relation [27]

α=

2.3036 log(1/T) t

where T is the transmittance and t is the thickness of the crystal. As a direct band gap, for high photon energies (hυ) the absorption coefficient (α) obey the following relation [28]

α=

(A(hυ ‒ Eg)1/2) hυ

where Eg is the optical band gap of the crystal and A is a constant. Optical band gap was determined by plotting a graph between (αhυ)

2

versus hυ [29] and extrapolating the

linear portion near the onset of absorption edge to the energy axis. The band gap energy of the material is found to be 3.89 eV. The large percentage transmission in the visible region enables it to be a good candidate for opto-electronic applications [30]. 3.3. FT-IR Spectral Studies The FT-IR spectrum of DASA crystal was depicted in Fig.5. The broad band at 3439 cm-1 represents O-H asymmetric stretching vibration [31]. This is presumably due to the

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involvement of phenolic OH in intramolecular hydrogen bonding with O atom of the COOgroup in the neighbourhood. The medium intensity sharp band observed at 3078 cm-1 is due to the aromatic C-H stretching vibration. The absorption bands at 2961 and 2629 cm1correspond

to the asymmetric and symmetric aromatic C-H stretching vibrations

respectively. The vibrational band at 2482 cm-1 is consistent with tertiary N+-H symmetric stretching vibration in N, N-Diethyl anilinium moiety [32]. The overtone and combination bands at 1964 and 1885 cm-1 confirm the presence of aromatic ring. The formation of the proton transfer salt is confirmed by appearance of strong asymmetric and symmetric stretching vibration bands of COO- group of 3,5-dinitrosalicylate ion at 1583 and 1451 cm-1, respectively [33]. The NO2 asymmetric stretching vibration of 3, 5-dinitrosalicylic acid moiety in the complex produces a band at 1530 cm-1and the corresponding symmetric stretching vibration mode is observed at 1344 cm-1 [34]. The absorption band at 1279 cm-1 corresponds to the C-O stretching vibration. The O-H in-plane-bending vibration is observed at 1160 cm-1. The band at 1071 cm-1 is assigned to C-H in-plane bending vibration. The absorption at 923cm-1 is corresponds to O-H out-of plane bending vibration. The C-N stretching vibration appears at 826 cm-1. The band at 736 cm-1 owes to the aromatic C-H out of plane bending vibration. The weak absorption at 701cm-1 is assigned to C-N-O in-planebending vibration. The vibrational bands observed below 500 cm-1 are due to the skeletal vibrations. The assignment of the well-defined bands in the infrared spectrum is given in Table 1. 3.4. NMR Spectral Studies The 1H NMR spectrum of the DASA crystal is depicted in Fig.6. In the 1H NMR spectrum, the appearance of six distinct proton signals confirms the presence of six different

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proton environments in the title compound. The phenolic OH proton signal of the 3, 5dinitrosalicylate moiety appears as small hump at 10.98 ppm. The appearance of proton signal at δ8.6ppm owes to the C4 and C6 aromatic protons of the same kind in 3, 5dinitrosalicylate moiety [35]. The proton signal at δ7.58 ppm is assigned to the C3 and C5 protons of the same kind in N, N-Diethyl anilinium moiety. A peak at δ7.5 ppm is owes to the C2, C4 and C6 protons of the same kind in N, N-Diethyl anilinium moiety. The quartet peak centered at δ3.5 ppm represents the protons due to two identical methylene protons coupling with methyl protons in N, N-Diethyl anilinium moiety. The high intense triplet centered at δ0.9 ppm represents methyl protons in N, N-Diethyl anilinium moiety. Due to the deprotonation of COOH group, the carboxylic acid proton signal of 3, 5-dintro salicylate moiety does not appear in 1H NMR spectrum which also confirms the formation of molecular salt. From the Fig.7, the appearance of eleven distinct carbon signals in the spectrum explicitly confirms the molecular structure of salt crystal. In the downfield carbon signal at δ 169.40 ppm owes to the highly deshielded carboxyl carbon of the 3, 5-dinitrosalicylate moiety [36]. The signal at δ 167.3 ppm is assigned to the C2 carbon of the 3, 5dinitrosalicylate moiety. The signal at δ 139 ppm is due to the C5 carbon of the 3, 5dinitrosalicylate moiety. The signal at δ 134.8 ppm is attributed to the C3 carbon of the 3, 5dinitrosalicylate moiety. The signals appearing at δ 130.9 ppm is attributed to the C6 carbon of 3, 5-dinitrosalicylate moiety. The signal at δ 130.4 ppm owes to the C4 carbons of the 3, 5-dinitrosalicylate moiety. The signal at δ 126 ppm is attributed to the C1 carbon of the 3, 5dinitrosalicylate moiety. The signal at δ 122.5 ppm is due to the C1 carbon of N, N-Diethyl anilinium moiety. The signal at δ 120.8 ppm is attributed to the C2, C4 and C6 carbons of the

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same kind in N, N-Diethyl anilinium moiety. The signal at δ 47.1 ppm is due to methylene carbon of N, N-Diethyl anilinium moiety. Another sharp and intense signal appearing at δ 8.2 ppm owes to methyl carbon of N, N-Diethyl anilinium moiety. The signal for C4 and C6 carbons of the same kind in N, N-Diethyl anilinium moiety is sub-merged with C1, C3 and C6 carbon of the 3, 5-dinitrosalicylate moiety. The 1H NMR and 13C NMR spectral data have been summarized in the Table 2. 3.5. Single Crystal XRD Analysis Single crystal X-ray diffraction analysis was carried out on well grown single crystal at 20°C to determine the structural and other bonding features of the title compound. The crystal structure was determined from the Single-Crystal X-ray diffraction data obtained with a X’calibur CCD area-detector diffractometer(Graphite–monochromated, Mo Kα =0.71073). The crystallographic data and structure refinements of title crystal are given in Table 3. The crystal belongs to monoclinic crystallographic system, P21/n space group. Lattice parameters have been determined as a = 6.8546(5) Å, b = 13.1589(10) Å, c = 20.4455(12) Å and the volume of the unit cells is found to be 1823.1(2) A3. Fig. 8 shows the ORTEP view of the molecule drawn at 50% probability thermal displacement ellipsoids with the atom numbering scheme. The selected bond lengths and bond angles are given in Tables 4. The acidic hydrogen deprived from 3, 5-dinitrosalicylic acid attaches to the nitrogen atom of N, Ndiethyl aniline. The assignment of crystalline compound as a salt is based on successful refinement of the relevant H atoms using X-ray data. This is further confirmed by the C-O distances (C(1)-O(1), 1.293(3) Å), C(1)-O(7), 1.221(3)) Å with ∆= 0.072 Å in the carboxylate group, which is in the range for the C-O distances concerning the deprotonated carboxyl groups[37]. The difference between the two bonds is attributed to the fact that O1

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atom is involved in formation of strong O-H…O intramolecular hydrogen bond with phenolic OH group than that of O7 of COO-group [38]. The asymmetric unit consists of one N, N-diethyl anilinium ion and one 3, 5-dinitrosalicylate ion which were held together by N+H…O-hydrogen bond between one O atom of the carboxylate group and the NH+ group to form a heterodimer through this hydrogen bonding interaction. There was also a CH3-O interaction between the methyl group of the cation and the oxygen atom of the phenol group with C-O distance of 3.414(4) Å to form a 1D chain running along the ‘b’ axis direction. The adjacent heterodimers were connected together through the CH2-O association between the CH2 of one cation and the NO2 of its adjacent anion with C…O distance of 3.360(3) Å. Due to the presence of the intramolecular hydrogen bonding between the carboxylate group and the phenol group (O(6)-H(61)…O(1), 2.413(3)Å), it is found that the carboxylate group is essentially coplanar with the benzene ring [torsion angle C(1)-C(2)-C(3)-O(6), 175.3(2) Å] [39]. Furthermore, the strength and direction of the N+-H…O, O-H…O (Intra molecular hydrogen bonding), and C-H…O hydrogen bonding interactions are strong enough to bring about the formation of the binary molecular salt and to stabilize the constitute ions in the crystal packing. Moreover, it is similar to that of salicylic acid [40]. The packing arrangement of molecule viewed down a, b and c axes showing hydrogen bonding is depicted in Fig. 9. The hydrogen bond interactions involved in the DASA is shown in Table 5. 3.6. Thermal Analysis The thermal stability of title DASA salt crystal was studied by thermo gravimetric (TG) and differential thermal analysis (DTA) and thermogram depicted in Fig.10. The powdered sample weighing 5.559 mg was used for these analyses in the temperature range of 30 to 500 °C at a heating rate of 20 °C per minute in nitrogen atmosphere. From the TG

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curve it is obvious that the decomposition takes place in a single step into gaseous products when the material is heated up to 500 °C. It is inferred that the melting point of the material takes place in the vicinity of 161°C. But before melting, there is no weight loss; hence the crystal is completely free of any entrapped or physically adsorbed solvent like methanol [41]. Further, it indicates no phase transition before melting. The DTA curve indicates the same changes shown by TG curve. The sharp endothermic dip at 161 °C is attributed to the melting point of the crystal. This further indicates that the material decomposes only after melting. The exothermic peak at 259 °C corresponds to the major decomposition temperature as has been indicated by TG curve as well. 3.7. Microhardness studies As the hardness of the crystal is one of the important parameters in determining the applicability of the specific device to its performance, it is vital to carry out hardness studies for the grown crystal. Microhardness studies have been carried out on the grown single crystal using HMV SHIMADZU tester, fitted with diamond Vickers pyramidal indenter. Hardness of the crystals was calculated using the relation

()

Hv = 1.8544

P

2

d

Kg/mm2

Where Hv is Vicker’s microhardness number, P is the indenter load and d is the diagonal length of the impression. The applied load was varied from 25 to 100g. Maximum indenter load applied on the crystal was 100g. When the load was increased to 100g, cracks developed on the smooth surface of the crystals. The plot of variation of Vicker’s hardness number with applied load and Plot of log d Vs log p for the plane of DASA crystal is shown

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in Fig.11. It is observed that the grown crystal exhibits reverse indentation size effect (ISE) that means, increase in hardness value with increasing load. In the Fig.12, by plotting log p verses log d, the value of the work hardening coefficient n was found to be 2.231 According to Onitsch[42], 1.0≤n≤1.6 for hard materials and n>1.6 for soft material. Hence, it is concluded that DASA crystal belongs to the soft material category. 3.8. Dielectric studies Dielectric measurement paves the way to exhibit the characterization of electrical response of the solids and can be correlated with electro-optic property of the crystal [43]. The dielectric study of the grown crystal was carried out for the frequencies range of 50 Hz 5 MHz at different temperatures (303 K, 313 K, 333 K, 353 K, and 373 K). The dielectric constant was calculated using the given formula

εr =

C pd εoA

Where, Cp is the measured parallel capacitance, d is the thickness of the crystal, A is the electrode area, εr dielectric constant and εₒ is the vacuum permittivity (8.85 x 10-12 F/m). The variation of dielectric constant and loss as a function of frequency at different temperatures are shown in Fig. 13 and 14 respectively. From the results, it is clear that the value of dielectric constant decreases with increase in frequency for all the temperatures and remains constant at higher frequencies. The large values of dielectric constant and loss at low frequencies may be due to the contribution from ionic, electronic, orientional and space charge polarization and its low value of dielectric constant and loss at high frequency may be due to the loss of magnitude of these polarizations gradually [44]. As the temperature

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increases, dipoles are free and respond to the applied electric field so the dielectric constant gets increased. The low dielectric constant and dielectric loss at higher frequencies clearly reveals that the title crystal possesses high optical quality and has low defects which are most important and desirable property of the crystalline materials for nonlinear optical applications [36]. 4. Conclusion N, N-diethylailinium 3, 5-dinitrosalicylate, an organic salt was synthesized and good optical quality single crystals of the title compound were grown by employing the slow solvent evaporation solution growth technique at room temperature. The single crystal XRD analysis revealed that the crystal belongs to monoclinic crystal system, P21/n. The UVVisible spectrum exhibits bands attributed to π-π* transitions of the constituent species present in the salt crystal. The UV-Vis-NIR transmission spectrum shows that the title crystal is good candidate for optical applications. The presence of various functional groups in the title crystal was confirmed by FT-IR spectrum. The formation of the salt and molecular structure was confirmed by 1H and 13C NMR spectroscopic technique. The thermal stability of the crystal was established by TG/DTA studies. Micro hardness studies indicated that the DASA crystal belongs to the soft-material category. The low value of dielectric constant and dielectric loss at high frequencies recommend that the grown crystal possesses better optical prominence with less defects. Hence, good transparency with wide band gap, thermal and stabilities, low dielectric loss and hydrogen bonding interactions of the title crystal indicate that it would be promising material for optical applications. Supplementary data

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CCDC 966862 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html (or from the Cambridge Crystallographic Data Centre, 12, Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033) or E-mail: [email protected]. Acknowledgements The authors gratefully acknowledge the School of Chemistry, University of Hyderabad, Hyderabad for providing instrumental facilities. One of the authors M. Rajkumar thanks the UGC Networking Centre, School of Chemistry, University of Hyderabad, for the award of visiting research fellowship to use the facilities at school of chemistry, University of Hyderabad, Hyderabad and grateful to Prof. S. K. Das, University of Hyderabad, Hyderabad for his support and help. References [1] E.D. D’silva, G.K. Podagatlapalli, S. Venugopal Rao, S.M. Dharmaprakash, Study on third-order nonlinear optical properties of 4-methylsulfanyl chalcone derivatives using picosecond pulses, Mater. Res. Bull. 47(2012)3552-3557. [2] M. Shkir, B. Riscob, V. Ganesh, N. Vijayan, Rahul Gupta, J.L. Plaza, E. Dieguez, G. Bhagavannarayana, Crystal growth, structural, crystalline perfection, optical and mechanical properties of Nd3+ doped sulfamic acid (SA) single crystals, J. Cryst. Growth 380(2013)228-235.

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Figure captions Fig.1. Reaction scheme of DASA crystal Fig.2. As-grown single crystals of DASA Crystal Fig.3.UV-Visible Spectrum of DASA Crystal Fig.4.UV-Vis-NIR Transmission Spectrum of DASA Crystal (Inset: Plot of (αhν) 2 versus photon energy) Fig.5. FT-IR Spectrum of DASA Crystal Fig.6. 1H NMR Spectrum of DASA Crystal Fig.7. 13C NMR Spectrum of DASA Crystal Fig.8. ORTEP view of the molecule drawn at 50% probability thermal displacement ellipsoids with the atom numbering scheme Fig.9. Packing arrangement of molecule viewed down the b-axis showing the hydrogen bonding (dashed blue lines) Fig.10. TG/DTA Thermogram of DASA Crystal Fig.11. Vicker’s hardness profile of DASA crystal as a function of applied load Fig.12. Plot of log d Vs log p for DASA crystal Fig.13. Plot of dielectric constant versus Log f at different temperatures for DASA crystal Fig.14. Plot of dielectric Loss versus Log f at different temperatures for DASA crystal

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C2H5 COOH

C2H5

N

C2H5

COO

OH

O2N

H OH

NO2

O2N

3,5-dinitrosalicylic acid N,N-diethylaniline

N

C2H5

NO2

N,N-diethylanilinium 3,5-ditrosalicylate

Fig.1. Reaction scheme of DASA crystal

Fig.2. As-grown single crystals of DASA Crystal

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Fig.3.UV-Visible Spectrum of DASA Crystal

Fig.4.UV-Vis-NIR Transmission Spectrum of DASA Crystal (Inset: Plot of (αhν) 2 versus photon energy)

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Fig.5. FT-IR Spectrum of DASA Crystal

Fig.6. 1H NMR Spectrum of DASA Crystal

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Fig.7. 13C NMR Spectrum of DASA Crystal

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Fig.8. ORTEP view of the molecule drawn at 50% probability thermal displacement ellipsoids with the atom numbering scheme

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Fig.9. Packing arrangement of molecule viewed down the a, b and c-axis showing the hydrogen bonding (dashed blue lines)

Fig.10. TG/DTA Thermogram of DASA Crystal

Fig.11. Vicker’s hardness profile of DASA crystal as a function of applied load

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Fig.12. Plot of log d Vs log p for DASA crystal

Fig.13. Plot of dielectric constant versus Log f at different temperatures for DESA crystal

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Fig.14. Plot of dielectric Loss versus Log f at different temperatures for DESA crystal

ACCEPTED MANUSCRIPT Highlights  Single crystals were grown by slow evaporation solution growth technique.  The NMR technique establishes the molecular structure of the crystal.  Formation of the salt was confirmed by single crystal X-ray diffraction analysis.  The crystal components were held together by N-H…O and O-H…O Hydrogen bonding.  The mechanical properties have been found out by Vicker’s microhardness study.

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Table captions Table 1 FT-IR Spectral Data of DASA Crystal Table 2 1H and 13C NMR chemical shift values of DASA crystal Table 3 Crystal data and structure refinement of DASA crystal Table 4 Bond lengths [Å] and angles [°] of DASA crystal Table 5 Hydrogen bonding geometry of DASA crystal

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Table 1 FT-IR Spectral data of DASA Crystal Wavenumber (cm-1)

Assignment

3439

O-H asymmetric stretching vibration

3078

Aromatic C-H stretching vibration

2961

C-H asymmetric stretching vibration of methyl group C-H symmetric stretching vibration of methyl group N+-H symmetric stretching vibration

2629 2482 1964&1885 1583

Combination and overtone vibration bands of aromatic ring COO- asymmetric stretching vibration

1530

NO2 asymmetric stretching vibration

1451

COO- symmetric stretching vibration

1344

NO2 symmetric stretching vibration

1279

C-O stretching vibration

1160

O-H inplane bending vibration

1073

C-H in-plane-bending vibration

923

O-H out of plane bending vibration

826

C-N stretching vibration

735

Aromatic C-H out of plane bending vibration

701

C-N-O in-plane-bending vibration

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Table 2 1H and 13C NMR chemical shift values of DASA crystal δ value (ppm) 1H

Assignments

NMR 10.98 8.6 7.58 7.5

13C

Phenolic OH proton signal of the 3, 5-dinitrosalicylate moiety C4 and C6 aromatic protons of the same kind in 3,5dinitrosalicylate moiety C3 and C5aromatic protons of the same kind in N,N-Diethyl aniline moiety C2, C4 and C6 aromatic protonsprotons of the same kind in N,N-Diethyl anilinium moiety

3.5

Methylene protons of N,N-Diethyl anilinium moiety

0.9

Methyl protons of N,N-Diethyl anilinium moiety

NMR 169.4

Carboxyl carbon of the 3,5-dinitrosalicylate moiety

167.3

C2 carbon of the 3,5-dinitrosalicylate moiety

139

C5 carbon of the 3,5-dinitrosalicylate moiety

134.8

C3 carbon of the 3,5-dinitrosalicylate moiety

130.9

C6 carbon of 3,5-dinitrosalicylate moiety

130.4

C4 carbon of the 3,5-dinitrosalicylate moiety

126

C1 carbon of the 3,5-dinitrosalicylate moiety

122.5

C1 carbon of N, N-Diethyl anilinium moiety

47.1

C2, C4 and C6 carbons of the same kind inN, N-Diethyl anilinium moiety Methylene carbon of N, N-Diethyl anilinium moiety

8.2

Methyl carbon N, N-Diethyl anilinium moiety

120.8

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Table 3 Crystal data and structure refinement of DASA crystal Empirical formula

C17 H19 N3 O7

Formula weight

377.35

Temperature

296(2) K

Wavelength

0.71073Å

Crystal system

Monoclinic

space group

P21/n

Unit cell dimensions

Volume

a = 6.8546(5) Å alpha = 90° b = 13.1589(10) Å beta = 98.66° c = 20.4455(12) Å gamma = 90° 1823.1(2) A3

Z, Calculated density

4, 1.375 Mg/m3

Absorption coefficient

0.108 mm-1

F(000)

792

Crystal size

0.35 x 0.30 x 0.20 mm

Theta range for data collection

1.85 to 28.12 deg.

Limiting indices

-9<=h<=8, -14<=k<=17, 26<=l<=27

Reflections collected / unique

13310 / 4375 [R(int) = 0.0370]

Completeness to theta = 28.12

98.4 %

Absorption correction

Semi-empirical from equivalents

Max. and min. transmission

0.9787 and 0.9631

Refinement method

Full-matrix least-squares on F2

Data / restraints / parameters

4375 / 0 / 246

Goodness-of-fit on F2

1.029

Final R indices [I>2sigma(I)]

R1 = 0.0635, wR2 = 0.1765

R indices (all data)

R1 = 0.1329, wR2 = 0.2138

Largest diff. peak and hole

0.343 and -0.325 e.A-3

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Table 4 Bond lengths [Å] and angles [°] of DASA crystal O(1)_ C(1)

1.293(3)

O(6) - C(3) - C(2)

120.4(2)

O(5) _ N(1)

1.185(4)

N(1) - C(4) - C(3)

121.2(2)

N(2) _ C(5)

1.451(3)

N(2) - C(5) - C(6)

119.4(2)

C(3) _ C(4)

1.416(3)

C(4) - C(6) - C(5)

119.3(2)

O(6) _ H(61)

0.82

C(3) - O(6) - H(61)

109

O(2) _ N(1)

1.175(4)

C(2) - C(7) - H(7)

120

O(6) _ C(3)

1.285(3)

O(2) - N(1) - C(4)

119.4(3)

C(1) _ C(2)

1.489(3)

O(3) - N(2) - C(5)

118.7(2)

C(4) _ C(6)

1.371(3)

O(1) - C(1) - C(2)

115.9(2)

C(6) _ H(6)

0.93

C(1) - C(2) - C(7)

118.9(2)

O(3) _ N(2)

1.211(3)

O(6) - C(3) - C(4)

123.7(2)

O(7) _ C(1)

1.221(3)

N(1) - C(4) - C(6)

116.7(2)

C(2) _ C(3)

1.413(3)

N(2) - C(5) - C(7)

119.4(2)

C(5) _ C(6)

1.366(3)

C(2) - C(7) - C(5)

119.7(2)

C(7) _ H(7)

0.93

C(4) - C(6) - H(6)

120

O(4) _ N(2)

1.213(3)

C(5) - C(7) - H(7)

120

N(1) _ C(4)

1.455(3)

O(5) - N(1) - C(4)

119.8(3)

C(2) _ C(7)

1.368(3)

O(4) - N(2) - C(5)

118.2(2)

O(7) - C(1) - C(2)

121.0(2)

C(5) _ C(7)

1.379(3)

O(1) _ C(1)

1.293(3)

C(3) - C(2) - C(7)

121.6(2)

O(5) _ N(1)

1.185(4)

C(2) - C(3) - C(4)

115.99(19)

N(2) _ C(5)

1.451(3)

C(3) - C(4) - C(6)

122.1(2)

C(3) _ C(4)

1.416(3)

C(6) - C(5) - C(7)

121.3(2)

O(2) - N(1) - O(5)

120.7(3)

C(5) - C(6) - H(6)

120

O(3) - N(2) - O(4)

123.1(2)

O(2) - N(1) - O(5)

120.7(3)

O(1) - C(1) - O(7)

123.1(2)

O(3) - N(2) - O(4)

123.1(2)

C(1) - C(2) - C(3)

119.47(19)

O(1) - C(1) - O(7)

123.1(2)

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Table 5 Hydrogen bonding geometry of DASA crystal S.No Donor-H...Acceptor

D-H

H...A

D...A

1

N(3)-H(3)…O(7)

0.91

1.83

2.738(3)

172

2

Intra O(6)- H(61)…O(1)

0.82

1.66

2.413(3)

152

3

C(14)-H(14C) …O(3)

0.96

2.58

3.360(3)

138

4

C(15)-H(15B) …O(6)

0.97

2.50

3.414(4)

156