Characterization of an NLO crystal-Diphenlamine

Indian Journal of Science

ANALYSIS

International Weekly Journal for Science ISSN 2319 – 7730

EISSN 2319 – 7749

© 2015 Discovery Publication. All Rights Reserved

Characterization of an NLO crystal - Diphenlamine Publication History Received: 28 December 2014 Accepted: 15 January 2015 Published: 25 March 2015

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Citation Raja R, Seshadri S, Santhanam V, Gnanasambandan T. Characterization of an NLO crystal - Diphenlamine. Indian Journal of Science, 2015, 14(43), 119-134

CHARACTERIZATION OF AN NLO CRYSTAL - DIPHENLAMINE R.Rajaa, S.Seshadrib*, V.Santhanamc, T. Gnanasambandand a

Department of Physics,SCSVMV University,Kanchipuram 631561, India b Department of Physics,L.N.Govt. Arts college, Ponneri 601204, India c Department of Physics,SCSVMV University,Kanchipuram 631561, India d Department of Physics, Pallavan college of Engineering, Kanchipuram-631501, India ABSTRACT

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1. Introduction Optical materials with excellent nonlinearities have been studied extensively for their applications in abundance for telecommunications, optic data storage, optical computing, optical bistability, optical information processing, color displays, etc. [1-3]. The NLO phenomena occur when the optical properties of molecules change in the presence of strong external electric fields, i.e., high energy laser beams. New organic crystals have been shown to have potential applications[4]. Advantages of organic materials involve amenability for synthesis, multifunctional substitution, higher resistance to optical damage and manoeuvrability for device application etc[5]. Molecular flexibility of organic materials is an added advantage to enhance the nonlinear optical properties in a desired manner[6]. In addition, they have large structural diversity. The sub networks induce non-centrosymmetry in the bulk and enhance the thermal and mechanical stabilities through hydrogen bonding interactions[7,8]. It has been demonstrated that organic crystals can have very large non-linear susceptibilities compared to inorganic crystals [9]. Second harmonic generation (SHG) measurements of organic nonlinear optical materials have already produced results, which by far, supersede those obtained from all the known inorganic alternatives. The polar organic materials from symmetric crystal structure which gives rise to

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The organic nonlinear optical crystal of Diphenylamine(DPA) has been successfully grown by slow evaporation technique. Functional groups of the Diphenylamine(DPA) were confirmed by FTIR. The optical transmittance of DPA recognized by UV-Vis-NIR studies and the lower cutoff wavelength of the single crystal and thus it could be perfomed as NLO material. The NLO property of the DPA crystal has been confirmed by second harmonic generation (SHG) technique and the efficiency of the grown crystal over KDP and urea. The thermal stability of DPA crystal has been studied by thermogravimetric analysis(TGA) and differential thermal analysis(DTA). The mechanical strength of the crystal has been measured by Vickers Microhardenss testing. A study on the Mulliken atomic charges, the electronic properties were performed by time-dependent DFT (TD-DFT) approach. The stability of molecule has been analyzed by using NBO/NLMO analysis. The molecular electrostatic potential has been mapped primarily for predicting sites and relative reactivities towards electrophilic and nucleophilic attack. The calculated HOMO and LUMO energies show that charge transfer occurs within these molecules. The temperature dependance of thermodynamic properties has been analyzed. Global and local reactivity descriptors have been calculated in order to have a deep insight into the molecule for further applications. Keywords: XRD, B3LYP, MEP, NLO,TGA Corresponding author: [email protected]

second-order nonlinear optical properties [10,11]. The main reason for enhanced SHG activity in organic materials is the chirality, wide transparency ranges in the visible and UV spectral regions and hydrogen bonds of the material [12]. DPA and its derivatives are studied by several authors. Thermodynamic properties and isomerization of DPA has been studied using Ab-initio method by Jimei Xiao etal[13]. The structure of DPA reported by Mark A. Rodriguez and Scott D. Bunge[14]. Yan Li etal to evaluvate the role of DPA in liver injuries[15]. The vibrational spectra of DPA have been reported by V. A. Naumov etal[16] and Torsional deformation effect on the N—H bond dissociation energy in diphenylamine studied by Peter Poliak, Adam Vaganek[17]. To the best of our knowledge, neither crystal growth, nor NLO studies of DPA has been reported. In this paper, we present the crystal studies and optical characterisation of Di Phenyl Amine(DPA). Basic characterization such as single crystal and powder X-ray diffraction analyses, Fourier transform infrared (FT-IR) analysis, thermo gravimetric analysis (TGA), differential thermal analysis (DTA), etching and UV–Vis spectroscopy studies have been carried out. In addition, the SHG response of the crystal has been tested.Calculations were performed with Gaussian 09W software by using TD-DFT methods with 6-31G (d,p) basis set. In order to provide templates for molecular modeling studies, experimental results obtained from X-ray crystallography and those from B3LYP methods have been compared. Theoretically predicted values have been compared with the experimentally measured data and also the results have been discussed.The crystal has non-centrosymmetric triclinic space group P1.

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3. Computational method The DFT calculations are important for understanding the fundamental vibrational properties and the electronic structure of the compounds. The entire calculations of DPA were carried out to utilizing the gradient corrected density functional theory (DFT) [21] with the Becke’s threeparameter hybrid functional (B3) [22] for the exchange part and the Lee–Yang–Parr (LYP) correlation function [23], accepted as a cost-effective approach, for the computation of molecular structure, vibrational frequencies and energies of optimized structures by using Gaussian 09 suite of quantum chemical codes [24]. Density functional theory (DFT) approaches using hybrid functional are frequently used to study the structural characteristics, vibrational and electronic properties, such as HOMO– LUMO energies, dipole moment, absorption wavelengths, and oscillator strengths have been calculated using B3LYP method of the TD-DFT [25–28], interactions among different orbitals,

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2. Sample Preparation For crystal growth, the standard method for growing is dissolving the precursor materials in stoichiometric ratio and then slowly evaporating the solvent [18,19]. For growth of single crystal from organic materials, purification of starting materials is an important step [20]. The commercially available AR grade DPA was taken to grow in the form of single crystal in ethanol as solvent. It was purified by recrystallization process. The saturation of DPA has been obtained by dissolving the recrystallized material with continuous stirring of the solution using a magnetic stirrer. The saturated solution has been further purified by filtering through the filter paper provided with fine pores of 1-micrometer porosity. The filtered solution has been tightly closed with thick filter paper so that the rate of evaporation could be minimized. Transparent optical quality single crystals of dimensions 0.53x0.10x0.10 mm3 have been obtained after 15 days. The grown crystal is shown in Figure 1.

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4. Experimental analysis 4.1 Molecular structure The single crystal of DPA have been subjected to X –ray diffraction studies using an Enraf Nonius Cad4 X-ray diffractometer, using MoKα radiation (λ =0.71073 Å) to determine the unit cell parameters and morphology. Details of the measurement and refinement are given in Table 1. From the single crystal XRD data for the grown (DPA) crystals it is observed that the crystal belongs to triclinic system with the space group of P1, With the following cell dimensions a=9.900(6), b=19.75(2), c=39.04(3) Ǻ and cell volume V=7379(11) Ǻ3. The density ρ was calculated from crystallographic data. The value obtained for ρ was 1.033 mg/m3. The DPA crystal is recognized as non centrosymmetric, thus satisfying one of the essential material requirements for the SHG activity of the crystals. 4.2 Second Harmonic Generation (SHG) The second harmonic generation (SHG) efficiency of DPA crystal has been determined by Kurtz and Perry powder technique[30,31]. The crystal in the form of powder and it has been packed densely between two transparent glass slides. Nd:YAG laser has been used as a light source. A fundamental laser beam of 1064 nm wavelength, 8 ns pulse in depth with 10Hz pulse rate was made to fall on sample cell. The power of the incident beam is 5.7 m J/pulse. The transmitted fundamental wave has been passed over a monochromater which separates 532 nm (SHG signal) from 1064 nm. The generation of SHG was confirmed by the emission of green light. KDP crystal has been powdered to the identical size of DPA and has been used as reference material in the SHG measurement. The SHG efficiency of DPA (1.8 mJ) is approximately 0.2 times that of KDP (8.8 mJ). 4.3 Non-linear optical effects The NLO activity provide the key functions for frequency shifting, optical modulation,optical switching and optical logic for the developing technologies in areas such as communication, signal processing and optical interconnections [32,33,34]. The key factors in the second-order NLO materials to provides a guideline for the design and synthesis of organic materials from to find Experimental measurements and theoretical calculations on molecular hyperpolarizability β [35,36,37]. Theoretical determination of hyperpolarizability is quite useful both in understanding the relationship between the molecular structure and nonlinear optical properties. Nonlinearity in organic chromophores can be synthetically modulated by varying the composition or length of conjugated p-systems and by

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and they are found to yield consistent results. The molecular electrostatic potential surface (MEPs) of the present molecule is illustrated and evaluated. The natural bonding orbital (NBO) calculation are performed using NBO 3.1 program as implemented in the GAUSSIAN 09W [24] package at DFT level in order to understand various second-order interactions between the filled orbital of subsystem and vacant of another subsystem, which is measure of the intermolecular delocalization or hyperconjugation. To calculate the NLO properties such dipole moment, mean polarizability and first static hyperpolarizability of the headline molecule the finite field approach DFT have been used. Moreover, GaussSum 2.2 [29] was used to calculate group contributions of the molecular orbitals and to prepare TDOS or DOS spectra. Finally, the calculated normal mode of vibrational frequencies will provide the thermodynamic properties using the principle of statistical mechanics.

evaluating the effects of various electron-donor and electron acceptor groups. The isotropic (or

average) linear polarizability is defined as [38]: The 27 components of 3D matrix can be reduced to 10 components due to Kleinman symmetry [39].

The calculations of the total molecular dipole moment (), linear polarizability () and first-order hyperpolarizability () from the Gaussian output have been explained in detail previously [40] and the DFT has been extensively used as an effective method to investigate the organic NLO materials [41]. The calculated first hyperpolarizability of DPA is about 0.6 times greater than those of urea (0.3728X10-30), compound having the higher βtot value, correspond to the low HOMO-LUMO energy gap. The above results show that DPA might have the NLO applications.

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4.4.2 Global and local reactivity descriptors The chemical reactivity descriptors has gained significant momentum due to their applications in various areas of chemistry, biology, rational drug design and computer-aided toxicity prediction [43]. Several systematic linear relationships between substituent groups and chemical properties have been developed [44-47]. In this regard it is necessary to mention that development of conceptual DFT has evolutionized various aspects of chemical reactivity by providing strong foundations for the qualitative concepts. With the help of global and local

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4.4 OTHER MOLECULAR PROPERTIES 4.4.1 Electronic properties of DPA The organic single crystals are mainly used in optical applications, the optical transmittance and the cutoff wavelength are important. The absorption spectra of the grown DPA are shown in Fig. 3. The optical absorption of DPA single crystals has been recorded in the region 200–1100 nm using Shimadzu UV–Vis spectrophotometer, which includes near UV, visible and far IR regions [42]. In the entire visible region, there are no characteristic absorptions of DPA. This nature in the visible region is required for nonlinear optical applications. The cut off wavelength of the DPA crystal is around 300 nm. The electronic absorption spectrum of DPA was measured in ethanol and water at room temperature. It is obvious that to use TD-DFT calculations to predict the electronic absorption spectra is a quite reasonable method. Because of this the excitation energies, absorbance and oscillator strengths for the title molecule at the optimized geometry in the ground state were obtained in the framework of TD-DFT calculations with the B3LYP/6-31G(d,p) method. The experimental absorption wavelengths (energies) and computed electronic values, such as absorption wavelength (k), excitation energies (E), oscillator strengths (f), and major contributions of the transitions and assignments of electronic transitions are tabulated in Table 3. The strong transition at 301.28 (nm) with an oscillator strength f=0.0797, energy 4.1153 eV in ethanol, the 302.60 (nm) with an oscillator strength f=0.0621, energy 4.0973 eV in gas phase. The comparison between the measured and computed UV-Vis data show at 278 (nm) experimental shows good agreement as shown in Table 3 with computed at 276 (nm) in ethanol. The observed transition from HOMO-LUMO is π → π*.

reactivity descriptors, it is now possible to analyze the chemical reactivity of the whole molecule as well as the site selectivity of an atom in it. Various reactivity descriptors as chemical potential, global hardness, electrophilicity have been calculated using the standard working equations and are listed in Table 4. Ionization potential and electron affinity are obtained as negative HOMO and LUMO energies respectively utilizing Koopman’s theorem [48] If the electron cloud is strongly held by the nucleus, the chemical species is ‘hard’ but if the electron cloud is loosely held by the nucleus, the system is ‘soft’. It is not physical observable. It is useful for the theoretical prediction of several physicochemical properties like the fundamentals of chemical bonding and aromaticity. It is shown that the aromaticity of peripheral topological path may be well described by superior finite difference schemes of electronegativity and chemical hardness indices in certain calibrating conditions. The hardness has been associated with the stability of chemical system. It corresponds to the gap between the HOMO and LUMO orbital energies. The larger the HOMO–LUMO energy gap the harder the molecule. From the HOMO LUMO energy gap, one can find whether the molecule is hard or soft. The soft molecules are more polarizable than the hard ones because they need small energy to excitation. Softness (S) is a property of a molecule that measures the extent of chemical reactivity.

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4.4.5 NBO/NLMO analysis NBO analysis is a powerful technique capable of generating intuitive chemical representations of otherwise complex quantum mechanical electronic structure results, yielding a localized ‘‘Lewis- like’’ description of bonding and reactivity. A useful aspect of the NBO method is that it gives information about interactions of both filled and virtual orbital spaces that could enhance the analysis of intra and inter molecular interactions. The second-order Fock-matrix was carried out to evaluate the donor-acceptor interactions in the NBO basis. The interactions result in a loss of occupancy from the localized NBO of the idealized Lewis structure into an empty non-Lewis orbital [51]. For each donor (i) and acceptor (j) the stabilization energy (E2) associated with the delocalization ij is determined as E2= -qi (Fij)2/ (j-i) Where qi is the donor orbital occupancy, i, j are diagonal elements (orbital energies) and Fij is the off-diagonal NBO Fock matrix element[52,53]. In NBO analysis large E(2) value shows the intensive interaction between electrondonors and electron-acceptors and greater the extent of conjugation of the whole system, the

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4.4.3 Molecular Electrostatic Potential The electrostatic potential has been used primarily for predicting sites, relative reactivities towards electrophilic attack, in the studies of biological recognition and hydrogen bonding interactions [49,50]. To predict reactive sites for electrophilic and nucleophilic attack for the investigated molecule, the MEP at the B3LYP/ 6-31+G(d,p) optimized geometry was calculated. The negative (red and yellow) regions of the MEP are related to electrophilic reactivity and the positive (blue) regions to nucleophilic reactivity as shown in Fig. 5. The importance of MEPs lies in the fact that it simultaneously displays molecular size, shape as well as positive, negative and neutral electrostatic potential regions in terms of color grading and is very useful in research of molecular structure with its physicochemical property relationship. The extreme limits of the electron density observed in DPA are – 7.706 x 10-3 (red) and +7.706 x 10-3 (blue). The MEP of DPA clearly indicates the electron rich centers of nitrogen atom.

possible intensive interactions are given in Table 5. In DPA, the interactions between the first lone pair of oxygen N1 and the antibonding of C8-C13 have the highest E(2) value around 30.19 kcal/mol. The Table 6 gives the occupancy of electrons and p-character [54] in significant NBO natural atomic hybrid orbitals. In C–H bonds, the hydrogen atoms have almost 0% of p character. On contrary, almost 100% p-character was observed in both the atoms of all the  bonding and antibonding between C2–C3, C4–C5, C6–C7, C8–C13, C9–C10, C11–C12. Similarly, 100% pcharacter was observed in the first lone pair of nitrogen N1. The natural localized molecular orbital (NLMO) analysis has been carried out since they show how bonding in a molecule is composed from orbitals localized on different atoms. The derivation of NLMOs from NBOs gives direct insight into the nature of the localized molecular orbital’s ‘‘delocalization tails’’ [55,56]. Table 6 shows significant NLMO’s occupancy, percentage from parent NBO and atomic hybrid contributions of DPA calculated at B3LYP level using 6-31G(d,p) basis set. The NLMO of bonding atom C8-C13 is the most delocalized NLMO and has only 81% contribution from the localized BD(2)of parent NBO, and the delocalization tail (19%) consists of the hybrids ofC9,C10,C11 and C12. Among the bonded orbitals, NLMO due to BD(2) C2–C3 has 82% contribution from the parent NBO and the delocalization tail consists of the hybrids of C4, C5, C6 and C7. This delocalization can also be observed in the perturbation theory energy analysis given in Table 5. 4.4.6 TGA Analysis The thermal stability of the grown crystal was identified by Thermo Gravimetric analysis(TGA) and Differential Thermal analysis (DTA) studies. The TGA deals with the change in the mass of a substance, continuously monitored as a function of temperature when it is heated. The DTA shows the variation of heat flow with temperature. The powdered sample of DPA was used for this analysis. The thermal gravimetric analysis of the compound was carried out between 20 and 600˚C at a heating rate of 10˚C /min in the nitrogen atmosphere using Netzsch instrument [57,58]. The characteristic curve of TGA-DTA are shown in figure 7. The results obtained from TGA and DTA thermal studies are shown in Fig. 8. There is a major weight loss between 150 and 230 ◦C with a maximum around 210 ◦C. This weight loss corresponds to 98.8%. This nature of weight loss illustrates that there is no volatilization with no fragmentation. The material is stable up to 140 ◦C and no phase transition occurs till the melting point of the crystal. From the differential thermal analysis, two sharp endothermic peaks are observed at 56.2 and 219◦C. The first endothermic peak at 56.2 ◦C represents the melting point of the DPA crystal and the second endothermic peak at 219 ◦C represents its boiling point.

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Optically good quality Single crystals of DPA were grown successfully using the slow evaporation technique. Single crystal X-ray diffraction studies were carried out to calculate the lattice parameters. FT-IR spectrum confirms the presence of functional groups and their vibrational assignments in DPA crystal. Optical transmission studies conform that DPA is transparent in the entire visible region. The TD-DFT calculations on the molecule provided deep insight into their electronic structures and properties. In addition, the calculated UV–Vis results are all in good agreement with the experimental data. The studies on the NLO property confirmed SHG efficiency of DPA crystal to be comparable to urea and KDP. The stability and

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5. Conclusion

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References [1] R.W. Boyd, Nonlinear Optics, Academic Press,Inc., San Diego, 1992. [2] B.E.A.Saleh, M.C.Teich, Fundamentals of Photonics,John Wiley& Sons, New York,1991. [3] M.H. Jiang, Q. Fang, Adv. Mater. 11 [4] Mallik T and Kar T 2007Mater. Lett.613826. [5] Sun Z H, Zhang G H, Wang X Q, Cheng X F, Liu X J, Zhu L, Fan Y, Yu G and Xu D 2008J. Cryst. Growth310 2842. [6] Datta A and Pati S K 2003J. Chem. Phys.1188420. [7] Criado A, Dianez M J, Garrido S P L, Fernandes I M, Belsley M E and De Gomes M 2000Acta Crystallogr. C 56888. [8] Zaccaro J, Salvestrini J P, Ibanez A, Ney P and Fontana M D 2000J. Opt. Soc. Am.17427. (1999)1147. [9] Narayan Bhat M and Dharmaprakash SM. J Cryst Growth 2002; 243:526. [10] S.G. Bhat, S.M. Dharmaprakash, J. Cryst. Growth 181,4 (1997) 390-394. [11] W.B. Hou, D. Xu, D.R. Yuan, M.G. Liu, Cryst. Res. Tech. 29 (1994) 939-944. [12] P. Sreeramana Aithal, H.S. Nagaraja, P. Mohan Rao, D.K. Avashi, A. Sharma, J. Appl Phys. 81 (1997) 7526-7528. [13] Jimei Xiao, Xuedong Gong, Yingnan Chiu, Heming Xiao,Journal of Molecular Structure (Theochem) 489 (1999) 151–157 [14] Mark A. Rodriguez and Scott D. Bunge, Acta Cryst. (2003). E59, o1123-o1125 [15] Yan Lib, Xin-ming Qi, Xiang Xue, Xiong-feiWu, Yuan-fengWu, Min Chen, Guo-zhen Xing, Yang Luan, Jin Ren,∗ Toxicology Letters 186 (2009) 111–114 [16] V. A. Naumov, M. A. Tafipol’skii, A. V. Naumov, and S. Samdal, Russian Journal of General Chemistry, Vol. 75, No. 6, 2005, pp. 923�932. [17] Peter Poliak, Adam Vaganek Acta Chimica Slovaca, Vol. 6, No. 2, 2013, pp. 182-186. [18] L. Zeng, M. Zha, M. Ardoino, P. Franzosi, L. Zanotti, G. Zuccalli, C. Paorici, J. Cryst. Growth 166(1996) 528-532. [19] P.M. Ushasree, R. Jayavel, C. Subramanian, P. Ramasamy, 197(1999) 216-220. [20] B.J. McArdle, J.N. Sherwood, The Growing of Organic Crystals in Advanced Crystal Growth, Prentice-Hall, New York,1987, pp.208. [21] P. Hohenberg, W. Kohn, Phys. Rev. 136 (1964) B864–B871. [22] A.D. Becke, J. Chem. Phys. 98 (1993) 5648–5652. [23] C. Lee, W. Yang, R.G. Parr, Phys. Rev. B 37 (1988) 785–789. [24] M.J. Frisch et al., GAUSSIAN 09, Revision A.1, Gaussian Inc., Wallingford, CT,2009. [25] M. Petersilka, U.J. Gossmann, E.K.U. Gross, Phys. Rev. Lett. 76 (1966) 1212–1215. [26] E. Runge, E.K.U. Gross, Phys. Rev. Lett. 52 (1984) 997–1000. [27] R. Bauernschmitt, R. Ahlrichs, Chem. Phys. Lett. 256 (1996) 454–464. [28] M. Karabacak, M. Cinar, A. Coruh, M. Kurt, J. Mol. Struct. 919 (2009) 26–33.

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intramolecular interactions have been interpreted by NBO/NLMO analysis and the transactions that give stabilization to the structure have been identified by second order perturbation energy calculations. The calculation of first order hyperpolarizability reveals that the title compound possesses good NLO properties. The TGA curve of this sample indicates that the sample is stable up to 140˚C and from DTA studies,the sharpness of the endothermic peak shows good degree of crystallinity of the grown crystal for possible applications in laser.

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[29] N.M. O’Boyle, A.L. Tenderholt, K.M. Langner, J. Comp. Chem. 29 (2008) 839–845. [30] D.S. Chemla, J. Zyss, Nonlinear optical properties of Organic Molecules and Crystals, vol.1-2,Academic Press Orlando, New York,1987. [31] S.K. Kurtz, T.T. Perry. J. Appl. phys. 39 (1968) 3798 [32] C. Andraud, T. Brotin, C. Garcia, F. Pelle, P. Goldner, B. Bigot, A. Collet, J. Am. Chem. Soc. 116 (1994) 2094–2101. [33] V.M. Geskin, C. Lambert, J.L. Bredas, J. Am. Chem. Soc. 125 (2003) 15651– 15658. [34] D. Sajan, H. Joe, V.S. Jayakumar, J. Zaleski, J. Mol. Struct. 785 (2006) 43–49. [35] Kechen Wu, Jaap G. Snijders, and Chensheng Lin, J. Phys. Chem B 106, 8954 (2002). [36] Rice JE, Handy NC (1991) J Chem Phys 94:4959–4971 [37] Li H, Han K, Shen X, Lu Z, Huang Z, Zhang W, Zhang Z, Bai L (2006) J Mol Strut (Theochem) 767:113–118 [38] R. Zhang, B. Du, G. Sun, Y.X. Sun, Spectrochim. Acta A 75 (2010) 1115–1120. [39] D.A. Kleinman, Phys. Rev. 126 (1962) 1977–1982. [40] K.S. Thanthiriwatte, K.M. Nalin de Silva, J. Mol. Struct.:THEOCHEM617 (2002)69-75 [41] Y.X. Sun, Q.L. Hao, Z.X. Yu, W.X. Wei, L.D. Lu, X. Wang, Mol. Phys.107(2009) 223– 229. [42] C.N.R. Rao, Ultraviolet and Visible Spectroscopy of Organic Compound, Printice Hall of India Pvt. Ltd., New Delhi, 1984. [43] P.K. Chattaraj, S. Nath, B. Maiti, Reactivity descriptors, in: J. Tollenaere, P.Bultinck, H.D. Winter, W. Langenaeker (Eds.), Computational Medicinal Chemistry for Drug Discovery, Marcel Dekker, New York, 2003, pp. 295–322. ch. 11. [44] C. Hansch, D. Hoekman, A. Leo, D. Weininger, C.D. Selassie, Chembioinformatics: comparative QSAR at the interface between chemistry and biology, Chem. Rev. 102 (2002) 783–812. [45] Y. Li, N.S. Evans, The Fukui function: a key concept linking frontier molecular orbital theory and the hard-soft-acid-base principle, J. Am. Chem. Soc. 117 (1995) 7756–7759; [46] P. Perez, Y. Simon- Manso, A. Aizman, P. Fuentealba, R. Contreras, Empirical Energy density relationships for the analysis of substituent effects in chemical reactivity, J. Am. Chem. Soc. 122 (2000) 4756–4762; [47] P. Thanikaivelan, V. Subramanian, R.J. Raghava, B.U. Nair, Application of quantum chemical descriptor in quantitative structure activity and structure property relationship, Chem. Phys. Lett. 323 (2000) 59–70. [48] T.A. Koopmans, Uber die Zuordnung von Wellenfunktionen und Eigenwerten zu den Einzelnen Elektronen Eines Atoms, Physica 1 (1993) 104–113. [49] J.S. Murray, K. Sen, Molecular Electrostatic Potentials, Concepts and Applications, Elsevier, Amsterdam, 1996. [50] E. Scrocco, J. Tomasi, in: P. Lowdin (Ed.), Advances in Quantum Chemistry,Academic Press, New York, 1978. [51] F. Weinhold, C.R. Landis, Chem. Educ. Res. Pract. Eur. 2 (2001) 91–104. [52] D.W. Schwenke, D.G. Truhlar, J. Chem. Phys. 82 (1985) 2418–2427. [53] M. Gutowski, G. Chalasinski, J. Chem. Phys. 98 (1993) 4728–4738 [54] A.E. Reed, L.A. Curtiss, F. Weinhold, Chem. Rev. 88 (1988) 899–926. [55] A.E. Reed, P.V.R. Schleye, Inorg. Chem. 27 (1988) 3969–3987. [56] R.J. Xavier, E. Gobinath, Spectrochim. Acta A 91 (2012) 248–255. [57] F.Q.Meng, M.K.Lu, Z.H.Yang, H.Zeng, Mater. Lett. 33 (1998) 265

[58] M. Krishnamohan, K. Jagannathan, S. Ponnusamy and C. Muthamizhchelvan J. Phy. and Chem. Solids, 72 (2011) 1273-1278.

Table 1 XRD data of DPA CRYSTAL Details of the experimental diffraction data collections and refinements. Empirical formula Formula weight Color, shape Temperature (K) Crystal size (mm) Crystal system Space group Lattice constants a (Å) b (Å) c (Å) α () β () γ () Volume (Å3) ρ Z

C12H11N

169.23 white, block 326 0.53x0.10x0.10 Triclinic P1 9.900(6) 19.75 (2) 39.04 (3) 103.41 (9) 96.20 (6)

90.05(7) 7379(11) 1.2 Mg/m3 16

6-31G(d,p) -1.0424

Parameters xxx

6-31G(d,p) -488.856

y

-0.3657

xxy

264.988

z

0.5443

xyy

40.3695



1.2315

yyy

-26.117

xx

202.142

xxz

-126.448

xy

-6.18411

xyz

-51.0133

yy

125.053

yyz

5.50328

xz

10.5931

xzz

5.58675

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Parameters x

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Table 2 The calculated ,  and  components of DPA using B3LYP/6-31G(d,p) method

yz

2.18873

yzz

-4.30693

zz

73.3948

zzz

3.80093

tot

400.5898

tot(esu)

0.23237X10-30

(esu)

0.3180x10-30

Table 3 UV-Vis excitation energy and oscillator strength of PNA calculated by TD-B3LYP/6-31G(d,p)

States cal S1 S2 S3

TD-B3LYP/6-31G(d,p) Gas Phase Water f E(eV) cal E(eV)

301.28 293.58 276.86

4.1153 4.2231 4.4783

0.0797 0.1123 0.0609

302.60 296.74 272.01

4.0973 4.1782 4.5580

Expt. f

obs 0.0621 298 0.0694 290 0.0422 278

Major Contributions HOMO->LUMO (92%) HOMO->L+1 (92%) HOMO->L+2 (84%)

Table 4 Molecular properties of DPA Molecular properties EHOMO(eV) ELUMO(eV) EHOMO-LUMO gap(eV) Ionisation potential(I)eV Electron affinity(A)eV

B3LYP 6-31G(d,p) -5.09918 -0.14500 -4.95418 5.09918 0.14500

Molecular properties Chemical hardness() Softness(S) Chemical potential() Electronegativity () Electrophilicity index ()

B3LYP 6-31G(d,p) 2.47709 0.4037 -2.62209 2.62209 -3.4377

Table 5 Second order perturbation theory analysis of Fock matrix in NBO basis of DPA

BD (2) C2 - C3 BD (2) C2 - C3 BD (2) C4 - C5 BD (2) C4 - C5 BD (2) C6 - C7 BD (2) C6 - C7 BD(2) C8-C 13

BD* (2) C4 - C5 BD *(2) C6 - C7 BD *(2) C2 - C3 BD *(2) C6 - C7 BD *(2) C2 - C3 BD *(2) C4 - C5 BD*(2) C9- C10

E(2)akJ/mol) E(j)–E(i)b (a.u.) F(i, j)c(a.u.)

19.62 18.96 19.28 20.02 20.10 19.04 16.83

0.27 0.27 0.27 0.27 0.27 0.27 0.27

0.066 0.065 0.065 0.066 0.066 0.064 0.061

129

Acceptor(j)

Page

Donor(i)

BD(2) C8-C 13 BD(2) C9- C10 BD(2) C9- C10 BD(2) C11- C12 BD(2) C11- C12 LP(1) N1 a

BD*(2) C11- C12 BD*(2) C8-C 13 BD*(2) C11- C12 BD*(2) C8-C 13 BD*(2) C9- C10 BD*(2) C8-C 13

21.99 21.93 16.75 16.69 21.63 30.19

0.28 0.27 0.27 0.26 0.27 0.27

0.070 0.070 0.061 0.060 0.068 0.084

E(2) means energy of hyper conjugative interaction (stabilization energy).

b

Energy difference between donor and acceptor I and j NBO orbitals. F(i, j) is the fork matrix element between i and j NBO orbitals.

c

Occupancy

BD (2) C2 - C3

2.0000

% from parent NBO 82.2791

BD (2)C4- C5

2.0000

82.4962

BD (2) C6- C7

2.0000

82.5278

BD (2) C8 – C 13

2.0000

81.2891

BD(2) C9 – C 10

2.0000

83.4286

BD(2) C11 – C 12

2.0000

83.0025

LP(1) N1

2.0000

89.6854

Hybrid contributions Atoms % C4 7.367 C5 2.405 C6 3.445 C7 3.849 C2 3.469 C3 4.064 C6 7.425 C7 2.327 C2 7.283 C3 2.488 C4 3.517 C5 3.940 C9 3.763 C10 3.485 C11 2.711 C12 8.413 C8 7.746 C11 3.393 C12 3.363 C13 1.985 C8 3.306 C9 2.550 C10 7.799 C13 3.233 C2 1.357 C8 3.586 C9 1.238 C13 1.325

Page

Bond

130

Table 6 Occupancy, percentage of p character of significant natural atomic hybrid of the NBO of DPA calculated at B3LYP/6-31G(d,p)

Table 7 Significant NLMO’s occupancy, percentage from parent NBO and atomic hybrid contributions of DPA calculated using B3LYP/6-31G(d,p) basis set Hybrid 1.00 1.00 0.7098(sp )C +0.7044 (sp )C

BD (2) C4 - C5

1.6655

0.7039(sp

1.00

BD (2) C6 - C7

1.6718

0.7042(sp

1.00

BD(2) C8-C 13

1.64508

0.6821(sp

1.00

BD(2) C9- C10

1.70045

0.7254(sp

1.00

1.00

BD(2) C11- C12

1.67802

0.7216(sp

1.00

1.00

LP(1) N 1

1.79496

sp

Fig. 1 DPA Crystal

1.00

)C+0.7103 (sp

1.00

)C

) C + 0.7100 (sp )C + 0.7312(sp

1.00

)C

1.00

) C + 0.6883 (sp ) C + 0.6923 (sp

)C )C )C

Atom C2 C3 C4 C5 C6 C7 C8 C13 C9 C10 C11 C12 N1

p.% 99.97 99.96 99.96 99.96 99.96 99.94 99.96 99.97 99.97 99.96 99.97 99.96 100

131

ED(e) 1.6605

Page

Bond BD (2) C2 - C3

Fig. 2 Optimized Structure of DPA

Page

132

Fig. 3 UV-Visible spectrum of DPA

Page

Fig. 5 MEP diagram of DPA

133

Fig. 4 DOS spectrum of DPA

10 0 .0 3 0 .0 0

9 0 .0

98.8%

8 0 .0 2 5 .0 0 7 0 .0

6 0 .0 219.0Cel 17.86u V

5 0 .0

15 .0 0

TG %

4 0 .0 10 .0 0

3 0 .0

2 0 .0 5 .0 0 10 .0

0 .0

56.2Cel -1.22u V 10 0 .0

2 0 0 .0

3 0 0 .0 T em p C el

4 0 0 .0

5 0 0 .0

6 0 0 .0

Fig.6.TGA/DTA analysis of DPA

134

0 .0 0

Page

DTA uV

2 0 .0 0