308 American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) ISSN (Print) 2313-4410, ISSN (Online) 2313-4402 © Global Society of Scientific Research and Researchers http://asrjetsjournal.org/ Determination of Reactive Properties of a Series of Mono- Functionalized Bis-tetrathiafulvalene Employing DFT Calculations Amel Bendjeddoua*, Tahar Abbazb, Abdelkrim Gouasmiac, Didier Villemind a,bLaboratory of Aquatic and Terrestrial Ecosystems, Org. and Bioorg. Chem. Group, University of Mohamed- Cherif Messaadia, Souk Ahras, 41000, Algeria cLaboratory of Organic Materials and Heterochemistry, University of Larbi Tebessi, Tebessa, 12000, Algeria dLaboratory of Molecular and Thio-Organic Chemistry, UMR CNRS 6507, INC3M, FR 3038, Labex EMC3, ensicaen & University of Caen, Caen 14050, France a,bEmail: amel.bendjeddou@univ-soukahras.dz; tahar.abbaz@univ-soukahras.dz cEmail: akgouasmia@hotmail.com dEmail: didier.villemin@ensicaen.fr Abstract Density functional Theory (DFT) calculations at the B3LYP/6-31G (d,p) level of theory are carried out to investigate the equilibrium geometry of the novel compounds 3(a-e). Moreover, The Molecular electrostatic Potential (MEP) analysis reveals the sites for electrophilic attack and nucleophilic reactions within the molecules. Additionally, the reactivity and reactive site within the mono-functionalized bis-tetrathiafulvalenes, dipole moment, theoretical study of the electronic structure, nonlinear optical properties (NLO), and natural bonding orbital (NBO) analysis are performed and discussed. Keywords: Tetrathiafulvalenes; density functional theory; computational chemistry; electronic structure; quantum chemical calculations. ------------------------------------------------------------------------ * Corresponding author. http://asrjetsjournal.org/ American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 29, No 1, pp 308-326 309 1. Introduction Tetrathiafulvalene (TTF) chemistry has a long history since the first discovery of its conductivity within the Nineteen Seventies [1,2]. Interests within the related molecules have spread into varied fields concerned with electroactive materials due to their potential for the electronic devices like field effect transistors (FETs) [3,4], and photovoltaic cells [5,6]. Carrier generation is the primary concern in order to obtain electroactive organic materials. The carriers in molecular conductors [7,8] are usually generated based on a charge-transfer mechanism between the electron donor and acceptor molecules, a mechanism that was proposed by Mulliken within the Fifties [9]. This mechanism is the underlying conception for carrier generation within the current molecular conductors, and thereafter has been extensively adopted for single-component molecular conductors [10]. Intensive search for interesting and promising organic materials to indicate highly conducting or even superconducting properties, unique magnetic ordering or interesting optical characteristics has resulted within the synthesis of new electron donor and acceptor molecules. An enormous majority of organic metal-like materials is derived of tetrathiafulvalene (TTF) including its symmetrical and unsymmetrical derivatives. By means of increasing development of computational chemistry within the past decade, the research of theoretical modeling of drug design, functional material design, etc., has become much more mature than ever. Several important physico-chemical properties of biological and chemical systems can be predicted from the first principles by varied computational techniques [11]. In recent years, density functional theory (DFT) has been a shooting star in theoretical modeling. the development of higher and better exchange-correlation functionals made it possible to calculate several molecular properties with comparable accuracies to traditional correlated ab initio ways, with a lot of favorable computational costs [12]. Literature survey disclosed that the DFT has a great accuracy in reproducing the experimental values of in geometry, dipole moment, vibrational frequency, etc. [13,14]. In recent years organic nonlinear optical (NLO) materials have attracted attention, due to their second or third order hyper-polarizabilities compared to those of inorganic NLO materials [15]. Several studies are being carried out to synthesize new organic materials with large second-order optical nonlinear property in order to satisfy present and future technological needs [16]. They find innumerable applications within the various fields like telecommunications, optical computing, and optical data storage. In the present work the geometrical parameters, Natural Bond Orbital (NBO) analysis and electrostatic potential were calculated using B3LYP method with 6-31G (d,p) as basis set. The electronic dipole moment (µ) and first order hyperpolarizability (β) value of the molecules are computed to study the Non-Linear Optical (NLO) property. NBO analyses were performed to provide valuable information regarding various intermolecular interactions. The calculated Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) energies show that charge transfer occurs within the molecules. Finally electronegativity (ϰ), hardness (η), softness (Ѕ) and Molecular electrostatic Potential maps (MEP) properties were calculated. 2. Materials and methods All the quantum chemical calculations have been carried out with Gaussian 09 program package to predict the molecular structure, NBO, NLO and energy of the optimized structures using B3LYP functional and 6-31G (d,p) basis set, which invokes Becke’s three parameter hybrid exchange functional (B3), with Lee-Yang-Parr correlational functional (LYP). The basis set 6-31G (d,p) with ‘d’ polarization functions on heavy atoms and ‘p’ American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 29, No 1, pp 308-326 310 polarization functions on hydrogen atoms are used for better description of polar bonds of molecule. 3. Results and discussion 3.1. Chemistry In a precedent work [17], we have explained the synthesis of bis-tetrathiafulvalenes indicated in Figure 4. The synthetic route used to lead to the target functional linker between TTF units, is based on the reaction between two different functions respectively attached to a specific TTF ring. To incorporate an ester function in a link between TTF units, a reaction involving an acid chloride function of a TTF and one hydroxyl group of another TTF ring was used. As shown in Figure 4, the use of monohydroxyTTF 2 [18-20] with 1.5 equiv. of acid chloride TTF 1 [21-23] led to a series of mono-functionalized bisTTF 3(a-e). S S S SR1 R1 O O S S S SE R R2 R2 with E= -CH2- 3a: R1= R2, R2 = S(CH2)2, R=H 49% 3b: R1=SMe,R2, R2=S(CH2)2,R=H 90% with E= p-C6H4 - 3c: R1=SMe,R2, R2=-CH=CH-CH=CH-, R=Me 57% with E= S(CH2)2 3d: R1=SMe, R2=Me, R=SMe 66% 3e: R1=SMe, R2,R2=S(CH2)2S, R=SMe 64% S S S SR1 R1 Cl O S S S SR2 R2 E OH R 1 2 3 Figure 4: Synthetic route for the preparation of mono-functionalized bisTTF 3(a-e) 3.2. Molecular geometry The optimized DFT geometries by B3LYP/6-31G (d,p) of the bis-TTF with atom numbering are shown in Figure 1. The internal coordinates describe the position of the atoms in terms of distances, angles and dihedral angles with respect to an origin atom. The symmetry coordinates are constructed using the set of internal coordinates. In this study, the standard internal coordinates for compounds 3(a-e) are presented in Tables 1-5. By allowing the relaxation of all parameters, the calculations converge to optimized geometries, which correspond to true energy minima, as revealed by the lack of imaginary frequencies in the vibrational mode calculation. American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 29, No 1, pp 308-326 311 Compound 3a Compound 3b Compound 3c Compound 3d Compound 3e Figure 1: Optimized molecular structure of mono-functionalized bisTTF 3(a-e) Table 1: Optimized geometric parameters of compound 3a Bond Length(Å) Bond Angles (°) Dihedral Angles (°) R(1,2) 1.350 A(2,1,7) 123.507 D(7,1,2,6) 178.288 R(1,7) 1.783 A(2,1,8) 123.849 D(2,1,7,24) 156.897 R(1,8) 1.781 A(7,1,8) 112.629 D(1,2,6,3) 169.553 R(2,5) 1.787 A(1,2,5) 123.142 D(6,3,4,22) 176.171 R(2,6) 1.782 A(1,2,6) 123.289 D(4,3,9,20) 102.355 R(3,4) 1.341 A(5,2,6) 113.563 D(6,3,9,10) 164.044 R(3,6) 1.779 A(13,12,20) 112.058 D(22,4,5,2) 176.572 R(3,9) 1.499 A(13,12,21) 123.526 D(1,8,23,29) 173.077 R(9,20) 1.452 A(20,12,21) 124.415 D(11,9,20,12) 153.158 R(12,13) 1.473 A(24,23,29) 123.841 D(20,12,13,14) 178.571 R(12,20) 1.356 A(7,24,30) 115.375 D(21,12,13,25) 175.893 R(12,21) 1.216 A(23,29,34) 96.395 D(13,12,20,9) 177.213 R(30,31) 1.862 A(24,30,31) 103.831 D(14,13,25,26) 177.544 R(31,32) 1.095 A(29,34,31) 113.017 D(13,14,16,17) 169.103 R(31,33) 1.092 A(37,42,44) 105.867 D(14,16,17,18) 178.211 American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 29, No 1, pp 308-326 312 Table 2: Optimized geometric parameters of compound 3b Bond Length(Å) Bond Angles (°) Dihedral Angles (°) R(1,2) 1.350 A(2,1,7) 123.526 D(7,1,2,5) 178.206 R(1,7) 1.783 A(2,1,8) 123.825 D(8,1,2,6) 156.955 R(1,8) 1.781 A(7,1,8) 112.633 D(6,2,5,4) 169.559 R(2,5) 1.787 A(1,2,5) 123.145 D(6,3,4,5) 176.224 R(2,6) 1.782 A(1,2,6) 123.293 D(4,3,9,11) 102.788 R(3,4) 1.341 A(5,2,6) 113.557 D(4,3,9,20) 164.498 R(3,6) 1.779 A(4,3,6) 116.574 D(3,4,5,2) 176.518 R(3,9) 1.499 A(4,3,9) 124.739 D(1,8,23,24) 172.973 R(9,10) 1.091 A(2,5,4) 94.687 D(10,9,20,12) 152.630 R(12,13) 1.472 A(2,6,3) 94.966 D(11,9,20,12) 177.370 R(12,20) 1.356 A(1,7,24) 93.592 D(21,12,13,25) 177.806 R(12,21) 1.216 A(1,8,23) 93.508 D(21,12,20,9) 175.362 R(13,25) 1.347 A(20,12,21) 124.397 D(25,13,14,16) 177.882 R(38,43) 1.837 A(28,37,39) 101.790 D(25,15,16,14) 169.738 R(39,40) 1.091 A(27,38,43) 101.648 D(15,16,17,18) 179.590 Table 3: Optimized geometric parameters of compound 3c Bond Length(Å) Bond Angles (°) Dihedral Angles (°) R(1,2) 1.350 A(2,1,7) 123.474 D(7,1,2,6) 179.255 R(1,7) 1.777 A(2,1,8) 123.451 D(2,1,7,10) 168.988 R(1,8) 1.777 A(7,1,8) 113.066 D(1,2,6,3) 160.155 R(2,5) 1.782 A(1,2,5) 123.839 D(6,3,4,46) 175.432 R(2,6) 1.784 A(1,2,6) 123.881 D(46,4,5,2) 171.541 R(3,4) 1.355 A(5,2,6) 112.274 D(3,4,46,42) 114.963 R(3,6) 1.781 A(12,11,13) 110.436 D(1,8,9,47) 173.541 R(3,17) 1.773 A(3,17,11) 101.290 D(47,9,10,7) 178.861 R(9,10) 1.345 A(18,19,20) 112.210 D(8,9,47,49) 174.507 R(18,19) 1.354 A(27,28,30) 94.526 D(10,9,47,50) 116.193 R(19,21) 1.215 A(27,29,31) 94.517 D(9,10,51,53) 124.011 R(23,26) 1.083 A(31,30,32) 125.697 D(13,11,12,15) 177.096 R(27,28) 1.779 A(30,32,34) 101.727 D(14,11,12,16) 177.404 R(27,29) 1.779 A(31,33,35) 101.807 D(17,11,12,18) 177.534 R(30,32) 1.766 A(32,34,37) 110.713 D(12,11,17,3) 165.179 American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 29, No 1, pp 308-326 313 Table 4: Optimized geometric parameters of compound 3d Bond Length(Å) Bond Angles (°) Dihedral Angles (°) R(1,2) 1.350 A(2,1,7) 123.430 D(7,1,2,6) 178.119 R(1,7) 1.783 A(2,1,8) 123.764 D(2,1,7,10) 158.535 R(1,8) 1.781 A(7,1,8) 112.773 D(1,2,6,3) 162.733 R(2,5) 1.781 A(1,2,5) 123.745 D(6,3,4,54) 175.459 R(2,6) 1.782 A(1,2,6) 123.723 D(54,4,5,2) 172.543 R(3,4) 1.355 A(5,2,6) 112.507 D(3,4,54,50) 115.052 R(3,6) 1.781 A(4,3,6) 117.056 D(1,8,9,11) 173.449 R(3,25) 1.773 A(1,8,9) 93.615 D(11,9,10,7) 171.756 R(9,10) 1.350 A(9,11,16) 96.355 D(7,10,12,13) 150.808 R(9,11) 1.763 A(10,12,13) 103.807 D(10,12,13,14) 127.959 R(10,12) 1.764 A(11,16,18) 107.939 D(21,19,20,23) 176.699 R(16,17) 1.094 A(17,16,18) 108.596 D(22,19,20,24) 177.055 R(26,27) 1.354 A(26,27,29) 124.093 D(25,19,20,26) 177.093 R(27,28) 1.474 A(38,40,42) 101.699 D(20,19,25,3) 163.877 R(27,29) 1.215 A(39,41,43) 101.844 D(19,20,26,27) 179.965 Table 5: Optimized geometric parameters of compound 3e Bond Length(Å) Bond Angles (°) Dihedral Angles (°) R(1,2) 1.368 A(2,1,25) 121.362 D(2,1,25,26) 141.099 R(1,25) 1.395 A(1,2,3) 110.943 D(1,2,3,5) 179.069 R(2,3) 1.472 A(1,2,4) 125.252 D(2,3,5,7) 175.122 R(2,4) 1.211 A(3,2,4) 123.805 D(2,3,6,8) 177.935 R(3,5) 1.776 A(2,3,5) 116.115 D(10,7,8,6) 169.580 R(3,6) 1.348 A(2,3,6) 126.269 D(8,7,10,12) 179.438 R(5,7) 1.785 A(10,11,13) 94.596 D(7,10,12,14) 158.762 R(6,8) 1.741 A(10,12,14) 94.604 D(10,11,13,15) 172.487 R(6,9) 1.083 A(13,15,17) 101.738 D(15,13,14,12) 172.903 R(7,10) 1.349 A(14,16,18) 101.877 D(14,13,15,17) 123.319 R(18,22) 1.091 A(1,25,27) 123.281 D(13,15,17,19) 177.341 R(42,43) 1.404 A(26,25,27) 120.991 D(1,25,26,28) 176.411 R(44,45) 1.086 A(28,26,29) 121.114 D(26,25,27,31) 179.216 R(46,48) 1.396 A(42,44,46) 119.408 D(25,26,28,33) 179.446 R(48,49) 1.085 A(54,53,56) 107.304 D(25,27,30,34) 178.127 American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 29, No 1, pp 308-326 314 3.3. Molecular electrostatic potential The molecular electrostatic potential V(r) that is created in the space around a molecule by its nuclei and electrons is well established as a guide to molecular reactive behavior. It is defined by: ''/)'(/)( rdrrrρrRZrV AA 3∫ −−−∑= In which ZA is the charge of nucleus A, located at RA, ρ(r') is the electronic density function for the molecule and r' is the dummy integration variable [24,25]. MEP is related to the electronic density and is a very useful descriptor in determining sites for electrophilic and nucleophilic reactions as well as hydrogen bonding interactions [26,27]. Being a real physical property, V(r) can be determined experimentally by diffraction or by computational methods [28]. However, identification of reactivity patterns based on the MEP exhibits intrinsic drawbacks, since the MEP is obtained through the classical electrostatic potential [29]. Then it is not possible to determine sites for nucleophilic attack because the zones of positive potential are not necessarily expressing affinity for nucleophiles but the concentrated nature of the nuclear charges. Molecular electrostatic potential mapping is very useful in the investigation of the molecular structure with its physiochemical property relationships [30-32]. The MEP map of bis-TTF 3(a-e) visibly suggests that the region around carbon atoms linked through double bond with oxygen atom represents the most negative potential region (red). The hydrogen atoms attached to the ends of the molecular chain beat the maximum bang of positive charge (blue). The color scheme for MEP surface is red, electron rich, partially negative charge; blue, electron deficient, partially positive charge; light blue, slightly electron deficient region; yellow, slightly electron rich region, respectively. The negative (red) region of MEP was related to electrophilic reactivity and the positive (blue) region to nucleophilic reactivity (Figure 2). -4.250e-2 4.250e-2 -4.044e-2 4.044e-2 Compound 3a Compound 3b -4.673e-2 4.673e-2 -4.593e-2 4.593e-2 Compound 3c Compound 3d American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 29, No 1, pp 308-326 315 -4.075e-2 4.075e-2 Compound 3e Figure 2: Molecular electrostatic potential surface of mono-functionalized bisTTF 3(a-e) 3.4. Frontier molecular orbitals (FMOs) The frontier molecular orbitals can offer a reasonable qualitative prediction of the excitation properties and the ability of electron transport [33,34]. The electronic absorption basically means the transition from the ground to the first excited state and is mainly described by one electron transition from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO). In other words, HOMO is the orbital that acts as an electron donor whereas LUMO is an orbital that acts as electron acceptor. The energy values of HOMO and LUMO and their energy gap reflect the chemical activity of the molecules. Figure 3 show the distributions and energy levels of the HOMO-1, HOMO, LUMO and LUMO+1 orbitals computed at the B3LYP/6-31G (d,p) level for compound 3c. Figure 3: HOMO-LUMO Structure with the energy level diagram of compound 3c 3.5. Global reactivity descriptors Global chemical reactivity descriptors of compounds such as hardness, chemical potential, softness, electronegativity and electrophilicity index as well as local reactivity has been defined [35-37]. Pauling introduced the concept of electronegativity as the power of an atom in a compound to attract electrons. Hardness American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 29, No 1, pp 308-326 316 (η), chemical potential (µ) electronegativity (χ) and softness are defined follows: ( ) ( ) ( ) ( )rvrv NENμη 22 2 1 2 1 ∂∂=∂∂= // ( ) ( ) χNEμ rv −=∂∂= / where E and ν(r) are the electronic energy and external potential of an N-electron system respectively. Softness is a property of compound that measures the extent of chemical reactivity. It is the reciprocal of hardness ηS 21 /= Using Koopman’s theorem for closed-shell compounds η, µ and χ can be defined as, ( ) ( ) χEEEAIEμ NN −=−=+−= −+ 22 11 // where A and I are the ionization potential and electron affinity of the compounds respectively. Electron affinity refers to the capability of legend to accept precisely one electron from a donor. However, in many kinds of bonding viz. covalent hydrogen bonding, partial charge transfer takes places. Recently Parr and his colleagues have defined a new descriptor to quantity the global electrophilic power of the compound as electrophilicity index (ω), which defines a quantitative classification of global electrophilic nature of a compound. Parr and his colleagues have proposed electrophilicity index (ω) as a measure of energy lowering due to maximal electron flow between donor and acceptor. They defined electrophilicity index (ω) as follows: ημω 22 /= Electrophilicity index is one of the important quantum chemical descriptors in describing toxicity or biological activities of the molecules in the context of development of Quantitative Structure-Activity Relationship (QSAR) parlance. Quantitative Structure-Activity Relationship (QSAR) methodology is one of the most powerful tools for describing the relationships between biological activity and the physicochemical characteristics of molecules. The molecular descriptor is the final result of a logic and mathematical procedure which transforms chemical information encoded within a symbolic representation of a molecule into a useful number or the result of some standardized experiment. Many of the descriptors are based directly on the results of quantum–mechanical calculations or can be derived from the electronic wave function or electrostatic field of the molecule [38]. Since the electrophilicity index is a chemical reactivity descriptor and it has been used as appropriate descriptor of QSAR study. Recently the electrophilicity index has been used as a possible descriptor of biological activity confirming the fact that the electrophilicity properly quantifies the biological activity. A previous QSAR study made with Multiple Linear Regression and found that the HOMO and LUMO energies are the most important descriptors for describing the drug-receptor interaction of the molecules [39]. It has found that electrophilicity is sufficient enough to describe the toxicity of the molecule. The usefulness of this new reactivity quantity has recently demonstrated in understanding the toxicity of various pollutants in terms of their reactivity and site selectivity [40]. HOMO and LUMO related properties are presented in Table 6. American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 29, No 1, pp 308-326 317 Table 6: Quantum chemical descriptors of mono-functionalized bisTTF 3(a-e) Parameters 3a 3b 3c 3d 3e EHOMO (eV) -4.798 -4.835 -4.721 -4.772 -4.943 ELUMO (eV) -1.666 1.712 -1.905 -1.627 -1.657 ΔEgap(eV) 3.132 6.548 2.816 3.144 3.285 IE (eV) 4.798 4.835 4.721 4.772 4.943 EA (eV) 1.666 -1.712 1.905 1.627 1.657 µ (eV) -3.232 -1.562 -3.313 -3.200 -3.300 χ (eV) 3.232 1.562 3.313 3.200 3.300 ƞ (eV) 1.566 3.274 1.408 1.572 1.643 S (eV) 0.319 0.153 0.355 0.318 0.304 ω (eV) 3.334 0.372 3.898 3.256 3.315 3.6. Local reactivity descriptors The site selectivity of a chemical system cannot be studied using the global reactivity descriptors. For this purpose, appropriate local reactivity descriptors as Fukui function to describe the reactivity of an atom in a molecule are needed to be defined. The local reactivity descriptors [41-43] such as Fukui functions (f +, f - , f 0) are calculated using the following equations as: ( ) ( )[ ]NqNqf −+=+ 1 , for nucleophilic attak, ( ) ( )[ ]1−−=− NqNqf , for electrophilic attak, ( ) ( )[ ] 2110 −−+= NqNqf , for radical attak. In these equations, q is the atomic charge (evaluated from Mulliken population analysis, electrostatic derived charge, etc.) at the kth atomic site is the neutral (N), anionic (N + 1) or cationic (N - 1) chemical species. Fukui functions for selected atomic sites in compounds 3(a-e) are shown in Tables 7-9. Table 7: Order of the reactive sites on compounds 3a and 3b Compound 3a Compound 3b Atom 24 C 28 C 2 C 16 C 27 C Atom 27 C 24 C 2 C 16 C 3 C f + 0.024 0.020 0.019 0.017 0.014 f + 0.050 0. 028 0.018 0.016 0.009 Atom 16 C 2 C 4 C 27 C 23 C Atom 16 C 2 C 4 C 23 C 27 C f - 0.056 0.020 0.013 0.009 0.006 f - 0.059 0.020 0.014 0.006 0.006 Atom 0.036 0.020 0.013 0.013 0.012 Atom 16 C 27 C 2 C 24 C 23 C f 0 16 C 2 C 24 C 28 C 27 C f 0 0.038 0.028 0.019 0.016 0.006 American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 29, No 1, pp 308-326 318 Table 8: Order of the reactive sites on compounds 3c and 3d Compound 3c Compound 3d Atom 3 C 1 O 32 C 13 C 43 C Atom 30 C 24 C 1 C 3 C 20 C f + 0.159 0.157 0.128 0.112 0.086 f + 0.050 0.015 0.014 0.010 0.006 Atom 7 C 25 C 36 C 37 C 14 C Atom 24 C 2 C 31 C 3 C 9 C f - 0.048 0.024 0.015 0.009 0.007 f - 0.039 0.026 0.007 0.003 0.002 Atom 3 C 1 O 32 C 13 C 7 C Atom 24 C 30 C 2 C 3 C 9 C f 0 0.076 0.073 0.058 0.058 0.057 f 0 0.027 0.025 0.013 0.007 0.003 Table 9: Order of the reactive sites on compound 7e Compound 3e Atom 38 C 10 C 9 C 32 C 2 C f + 0.049 0.015 0.015 0.015 0.010 Atom 32 C 2 C 19 C 9 C 39 C f - 0.037 0.027 0.012 0.006 0.004 Atom 32 C 38 C 2 C 9 C 10 C f 0 0.026 0.026 0.019 0.010 0.009 3.7. Natural bond orbital analysis (NBO) The stabilization energies of the title compounds were computed by using second-order perturbation theory in order to investigate the intra and intermolecular interactions, interaction among bonds, conjugative interactions. For each donor NBO(i) (Natural Bond Orbital) and acceptor NBO(j), the stabilization energy E(2) associated with electron delocalization between donor and acceptor is estimated as [44,45]. ij 2 iij E-E j)(i,FqΔE)E( ==2 where qi is the donor orbital occupancy, Ei, Ej are diagonal elements (orbital energies) and Fij is the off-diagonal NBO Fock matrix element. The results of second-order perturbation theory analysis of the Kohn-Sham Matrix at B3LYP/6-31G (d,p) level of theory are presented in Tables 10-14. American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 29, No 1, pp 308-326 319 Table 10: Second order perturbation theory analysis of Fock matrix on NBO of compound 3a Donor(i) ED/e Acceptor(j) ED/e E Kcal/mol E(j)-E(i) a.u F(i.j) a.u LP(2)O20 1.79953 π*C12-O21 0.27738 46.99 0.33 0.113 LP(2)O21 1.84092 δ*C12-O20 0.10457 33.49 0.62 0.131 LP(2)S15 1.73305 π*C13-C25 0.25974 25.61 0.26 0.072 LP(2)S5 1.76194 π*C3-C4 0.23117 23.11 0.26 0.069 LP(2)S14 1.77661 π*C13-C25 0.25974 21.12 0.25 0.065 LP(2)S6 1.78107 π*C3-C4 0.23117 20.76 0.26 0.066 LP(2)S19 1.79602 π*C27-C28 0.36707 19.58 0.24 0.063 LP(2)S8 1.79987 π*C23-C24 0.36681 19.42 0.24 0.063 LP(2)S7 1.80019 π*C23-C24 0.36681 19.39 0.24 0.063 LP(2)S18 1.79869 π*C27-C28 0.36707 19.30 0.24 0.063 πC13-C25 1.90090 π*C12-O21 0.27738 18.46 0.31 0.070 LP(2)O21 1.84092 δ*C12-C13 0.06571 18.36 0.70 0.103 LP(2)S37 1.85590 π*C27-C28 0.36707 17.41 0.24 0.061 LP(2)S30 1.85679 π*C23-C24 0.36681 17.30 0.24 0.061 LP(2)S14 1.77661 π*C16-C17 0.37904 17.25 0.25 0.062 LP(2)S6 1.78107 π*C1-C2 0.38033 16.95 0.26 0.062 LP(2)S5 1.76194 π*C1-C2 0.38033 16.87 0.26 0.061 LP(2)S15 1.73305 π*C16-C17 0.37904 16.30 0.26 0.060 LP(2)S18 1.79869 π*C16-C17 0.37904 13.23 0.25 0.054 LP(2)S19 1.79602 π*C16-C17 0.37904 13.16 0.25 0.054 Table 11: Second order perturbation theory analysis of Fock matrix on NBO of compound 3b Donor(i) ED/e Acceptor(j) ED/e E Kcal/mol E(j)-E(i) a.u F(i.j) a.u LP(2)O20 1.79971 π*C12-O21 0.27779 47.06 0.33 0.113 LP(2)O21 1.84103 δ*C12-O20 0.10462 33.49 0.62 0.131 LP(2)S15 1.73486 π*C13-C25 0.25983 25.63 0.26 0.072 LP(2)S5 1.76231 π*C3-C4 0.23109 23.08 0.26 0.069 LP(2)S14 1.77933 π*C13-C25 0.25983 21.11 0.25 0.065 LP(2)S6 1.78100 π*C3-C4 0.23109 20.79 0.26 0.066 LP(2)S8 1.80003 π*C23-C24 0.36694 19.39 0.24 0.063 LP(2)S19 1.78788 π*C27-C28 0.31178 19.36 0.25 0.063 LP(2)S7 1.80040 π*C23-C24 0.36694 19.35 0.24 0.063 LP(2)S18 1.79148 π*C27-C28 0.31178 18.98 0.25 0.063 πC13-C25 1.90102 π*C12-O21 0.27779 18.48 0.31 0.070 LP(2)O21 1.84103 δ*C12-C13 0.06562 18.34 0.70 0.103 LP(2)S30 1.85645 π*C23-C24 0.36694 17.48 0.24 0.061 LP(2)S14 1.77933 π*C16-C17 0.37934 17.10 0.26 0.061 LP(2)S6 1.78100 π*C1-C2 0.38029 16.94 0.26 0.062 LP(2)S5 1.76231 π*C1-C2 0.38029 16.84 0.26 0.061 LP(2)S15 1.73486 π*C16-C17 0.37934 16.18 0.27 0.06 LP(2)S19 1.78788 π*C16-C17 0.37934 13.79 0.25 0.055 LP(2)S18 1.79148 π*C16-C17 0.37934 13.71 0.26 0.055 LP(2)S8 1.80003 π*C1-C2 0.38029 12.84 0.26 0.054 American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 29, No 1, pp 308-326 320 Table 12: Second order perturbation theory analysis of Fock matrix on NBO of compound 3c Donor(i) ED/e Acceptor(j) ED/e E Kcal/mol E(j)-E(i) a.u F(i.j) a.u π*C43-C50 0.40147 π*C46-C48 0.34645 204.23 0.02 0.083 π*C42-C44 0.40165 π*C46-C48 0.34645 203.18 0.02 0.083 LP(2)O1 1.78787 π*C2-O4 0.26951 42.78 0.34 0.109 LP(2)O4 1.83434 δ*O1-C2 0.11477 36.52 0.61 0.135 LP(2)S8 1.73259 π*C3-C6 0.26286 25.91 0.25 0.073 πC46-C48 1.66399 π*C42-C44 0.40165 21.65 0.26 0.069 πC46-C48 1.66399 π*C43-C50 0.40147 21.64 0.26 0.069 πC26-C28 1.67780 π*C25-C27 0.37240 21.45 0.28 0.070 LP(2)S5 1.78027 π*C3-C6 0.26286 21.10 0.24 0.065 πC25-C27 1.64899 π*C30-C32 0.37522 20.65 0.29 0.070 πC30-C32 1.64612 π*C26-C28 0.32020 20.54 0.28 0.068 πC30-C32 1.64612 π*C25-C27 0.37240 20.44 0.27 0.067 LP(2)S38 1.78315 π*C37-C52 0.24718 19.45 0.27 0.066 LP(2)S12 1.78711 π*C13-C14 0.31289 19.33 0.25 0.063 πC25-C27 1.64899 π*C26-C28 0.32020 19.31 0.29 0.068 LP(2)S11 1.79087 π*C13-C14 0.31289 18.95 0.25 0.063 πC43-C50 1.68329 π*C42-C44 0.40165 18.72 0.28 0.066 πC42-C44 1.68350 π*C43-C50 0.40147 18.71 0.28 0.066 πC26-C28 1.67780 π*C30-C32 0.37522 18.64 0.28 0.066 πC3-C6 1.89840 π*C2-O4 0.26951 18.50 0.31 0.070 Table 13: Second order perturbation theory analysis of Fock matrix on NBO of compound 3d Donor(i) ED/e Acceptor(j) ED/e E Kcal/mol E(j)-E(i) a.u F(i.j) a.u LP(2)O18 1.80391 π*C19-O21 0.27379 47.07 0.33 0.114 LP(2)O21 1.84121 δ*O18-C19 0.10285 33.96 0.63 0.132 LP(2)S25 1.73800 π*C20-C23 0.25889 25.34 0.26 0.072 LP(2)S6 1.77855 π*C3-C4 0.31286 21.64 0.23 0.065 LP(2)S22 1.77796 π*C20-C23 0.25889 21.25 0.25 0.065 LP(2)S5 1.78613 π*C3-C4 0.31286 20.71 0.23 0.064 LP(2)S8 1.78918 π*C9-C10 0.23221 19.66 0.27 0.066 LP(2)S7 1.79030 π*C9-C10 0.23221 19.55 0.27 0.066 LP(2)S29 1.78831 π*C30-C31 0.31265 19.33 0.25 0.063 LP(2)S28 1.79189 π*C30-C31 0.31265 18.95 0.25 0.063 LP(2)O21 1.84121 δ*C19-C20 0.06706 18.75 0.69 0.104 πC20-C23 1.90481 π*C19-O21 0.27379 17.91 0.31 0.070 LP(2)S22 1.77796 π*C24-C27 0.37890 17.06 0.25 0.061 LP(2)S8 1.78918 π*C1-C2 0.38191 16.98 0.26 0.062 LP(2)S7 1.79030 π*C1-C2 0.38191 16.93 0.26 0.062 LP(2)S25 1.73800 π*C24-C27 0.37890 16.10 0.26 0.060 LP(2)S29 1.78831 π*C24-C27 0.37890 13.68 0.25 0.055 LP(2)S28 1.79189 π*C24-C27 0.37890 13.60 0.26 0.055 LP(2)S6 1.77855 π*C1-C2 0.38191 13.50 0.26 0.055 LP(2)S5 1.78613 π*C1-C2 0.38191 13.22 0.26 0.055 American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 29, No 1, pp 308-326 321 Table 14: Second order perturbation theory analysis of Fock matrix on NBO of compound 3e Donor(i) ED/e Acceptor(j) ED/e E Kcal/mol E(j)-E(i) a.u F(i.j) a.u LP(2)O26 1.80464 π*C27-O29 0.27348 46.89 0.33 0.114 LP(2)O29 1.84110 δ*O26-C27 0.10313 34.05 0.63 0.132 LP(2)S33 1.73746 π*C28-C31 0.25938 25.42 0.26 0.072 LP(2)S6 1.76857 π*C3-C4 0.31247 21.82 0.23 0.065 LP(2)S30 1.77822 π*C28-C31 0.25938 21.25 0.25 0.065 LP(2)S5 1.77589 π*C3-C4 0.31247 20.90 0.23 0.064 LP(2)S8 1.79305 π*C9-C10 0.36710 19.61 0.24 0.063 LP(2)S7 1.79465 π*C9-C10 0.36710 19.47 0.24 0.063 LP(2)S37 1.78805 π*C38-C39 0.31280 19.35 0.25 0.063 LP(2)S36 1.79211 π*C38-C39 0.31280 18.91 0.25 0.063 LP(2)O29 1.84110 δ*C27-C28 0.06701 18.76 0.69 0.104 πC28-C31 1.90449 π*C27-O29 0.27348 17.96 0.31 0.070 LP(2)S12 1.85693 π*C9-C10 0.36710 17.29 0.24 0.061 LP(2)S30 1.77822 π*C32-C35 0.37896 17.06 0.26 0.061 LP(2)S33 1.73746 π*C32-C35 0.37896 16.11 0.27 0.06 LP(2)S6 1.76857 π*C1-C2 0.37299 15.01 0.26 0.058 LP(2)S5 1.77589 π*C1-C2 0.37299 14.74 0.26 0.057 LP(2)S37 1.78805 π*C32-C35 0.37896 13.69 0.25 0.055 LP(2)S36 1.79211 π*C32-C35 0.37896 13.63 0.26 0.055 LP(2)S8 1.79305 π*C1-C2 0.37299 13.52 0.26 0.055 3.8. Nonlinear optical properties (NLO) Non-linear optics deals with the interaction of applied electromagnetic fields in various materials to generate new electromagnetic fields, altered in wave number, phase or other physical properties [46]. Organic molecules able to manipulate photonic signals efficiently are of importance in technologies such as optical communication, optical computing and dynamic image processing [47,48].In this context the first hyperpolarizability of the title compounds are also calculated in the present study. The first hyperpolarizability of these novel molecular systems is calculated using DFT method based on the finite field approach. In the presence of an applied electric field, the energy of a system is a function of the electric field. First hyperpolarizability is a third rank tensor that can be described by a 3 × 3 × 3 matrix. The 27 components of the 3D matrix can be reduced to 10 components due to the Kleinman symmetry [49].The components of β are defined as the coefficients in the Taylor series expansion of the energy in the external electric field. When the electric field is weak and homogeneous, this expansion becomes ...1/61/2 += kjiijkjiijii 0 FFFβ-FFα-Fμ-EE Where E0 is the energy of the unperturbed molecules, Fi is the field at the origin and µi, αij, βijk are the components of dipole moment, polarizability, and first hyperpolarizability, respectively. The total static dipole moment (µ0), anisotropy of the polarizability (α0), mean polarizability (Δα) and the total first hyperpolarizability (β0) using (x, y, z) components are defined as [50]: American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 29, No 1, pp 308-326 322 [ ] 21222 / zyxtot μμμμ ++= ( ) 3/αααα zzyyxx ++= ( ) ( ) ( )[ ] 2122222221 6662 / yzxyxz xxzz zzyy yyxx / αααααααααΔα +++−+−+−= − ( ) 21222 / zyxtot ββββ ++= xzzxyzxxxx ββββ ++= yzzxxyyyyy ββββ ++= yyzxxzzzzz ββββ ++= The total molecular dipole moment and first order hyperpolarizability are depicted in Table 15. The calculated hyperpolarizability of the title compounds is 35 times that of the standard NLO material urea (0.13 × 10 -30 esu) [51]. We conclude that the title compound is an attractive object for future studies of nonlinear optical properties. Table 15: The dipole moments µ (D), polarizability α, the anisotropy of the polarizability Δα (esu), and the first hyperpolarizability β (esu) of mono-functionalized bisTTF 3(a-e) Parameters 3a 3b 3c 3d 3e βxxx -209.359 -778.587 -580.589 1118.394 1189.897 Βyyy 8.506 -31.028 -1.019 53.188 68.992 Βzzz 26.877 24.484 14.619 70.880 48.589 Βxyy 70.081 -60.440 16.835 -30.674 -62.454 Βxxy -309.639 -352.577 -137.981 93.809 94.802 Βxxz -367.971 -41.763 152.570 146.644 -13.529 Βxzz -14.926 77.194 101.103 -0.310 18.116 Βyzz 6.951 -16.369 2.679 18.449 24.573 Βyyz 1.798 -30.645 26.160 6.765 16.505 Βxyz 28.556 -23.692 -3.285 64.776 86.647 Βtot(esu)x10-33 4232.154 3745.054 4644.659 10498.923 11311.488 µx -0.301 -4.020 -0.684 5.192 4.415 µy -2.455 -3.153 -1.715 3.733 4.096 µz -0.627 -1.399 1.925 2.083 0.576 µtot(D) 2.551 5.298 2.668 6.725 6.050 αxx -175.240 -265.272 -278.053 -230.246 -255.669 αyy -268.402 -246.876 -268.195 -281.183 -306.831 αzz -264.279 -262.969 -290.406 -277.582 -302.777 αxy -11.554 8.443 4.701 -18.614 -26.527 αxz 6.460 6.237 39.426 -21.237 -36.121 αyz 7.265 -1.468 2.619 7.068 8.736 α(esu)x10-24 -34.971 -38.291 -41.331 -38.977 -42.745 ∆α(esu)x10-24 14.056 3.744 10.606 10.444 13.808 American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 29, No 1, pp 308-326 323 4. Conclusion From the whole of the results presented in this contribution it has been clearly demonstrated that the sites of interaction of the title compounds 3(a-e) can be predicted by using DFT-based reactivity descriptors such as the hardness, softness, and electrophilicity, as well as Fukui-function calculations. These descriptors were used in the characterization and successfully description of the preferred reactive sites and provide a firm explanation for the reactivity of the mono-functionalized bis-tetrathiafulvalenes. NBO and NLO analysis reveals that the some important intramolecular charge transfer can induce large nonlinearity to the title molecules and the intramolecular conjugative interaction around the tetrathiafulvalene core can induce the large conductivity in the compounds. Finally we hope that these consequences will be of assistance in the quest of the experimental and theoretical evidence for the title compounds in molecular bindings. Acknowledgments This work was generously supported by the (General Directorate for Scientific Research and Technological Development, DGRS-DT) and Algerian Ministry of Scientific Research. References [1] Wudl F, Wobschall D, Hufnagel E J. Electrical conductivity by the bis(1,3-dithiole)-bis(1,3-dithiolium) system. J. Am. Chem. Soc. 94: 670-672; 1972. [2] Ferraris J, Cowan D O, Walatka VV, Perlstein JH. Electron transfer in a new highly conducting donor- acceptor complex. J. Am. Chem. Soc. 95: 948-949; 1973. [3] Torrent MM, Durkut M, Hadley P, Ribas X, Rovira C. High Mobility of Dithiophene- Tetrathiafulvalene Single-Crystal Organic Field Effect Transistors. J. Am. Chem. Soc. 126: 984-985; 2004. [4] Bendikov M, Wudl F, Perepichka DF. Tetrathiafulvalenes, Oligoacenenes, and Their Buckminsterfullerene Derivatives:  The Brick and Mortar of Organic Electronics. Chem. Rev. 104: 4891-4945; 2004. [5] Hou Y, Chen Y, Liu Q, Yang M, Wan X, Yin S, Yu A. A Novel Tetrathiafulvalene- (TTF-) Fused Poly(aryleneethynylene) with an Acceptor Main Chain and Donor Side Chains: Intramolecular Charge Transfer (CT), Stacking Structure, and Photovoltaic Property. Macromolecules. 41: 3114-3119; 2008. [6] Kanato H, Narutaki M, Takimiya K, Otsubo T, Harima Y. Synthesis and Photovoltaic Properties of Tetrathiafulvalene-Oligothiophene-Fullerene Triads. Chem. Lett. 35: 668-669; 2006. [7] Yamada J, Akutsu H, Nishikawa H, Kikuchi K. New trends in the synthesis of π-electron donors for molecular conductors and superconductors. Chem. Rev. 104: 5057-5083; 2004. [8] Mori H. Materials Viewpoint of Organic Superconductors. J. Phys. Soc. Jpn. 75: 051003; 2006. [9] Mulliken RS. Molecular Compounds and their Spectra. J. Am. Chem. Soc. 74: 811-824; 1952. [10] Kobayashi A, Fujiwara E, Kobayashi H. Single-Component Molecular Metals with Extended-TTF Dithiolate Ligands. Chem. Rev. 104: 5243-5264; 2004. [11] Zhang Y, Guo ZJ, You XZ. Hydrolysis Theory for Cisplatin and Its Analogues Based on Density American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 29, No 1, pp 308-326 324 Functional Studies. J. Am. Chem. Soc. 123: 9378-9387; 2001. [12] Proft FD, Geerlings P. Conceptual and Computational DFT in the Study of Aromaticity. Chem. Rev. 101: 1451-1464; 2001. [13] Fitzgerald G, Andzelm J. Chemical applications of density functional theory: comparison to experiment, Hartree-Fock, and perturbation theory. J. Phys. Chem. 95: 10531-10534; 1991. [14] Tanak H. Crystal Structure, Spectroscopy, and Quantum Chemical. Int. J. Quant. Chem. 112: 2392- 2402; 2012. [15] Gupte SS, Marcano A, Pradhan RD, Desai CF, Melikechi J. Pump-probe thermal lens near-infrared spectroscopy and Z-scan study of zinc (tris) thiourea sulfate. J. Appl. Phys. 89: 4939-4943; 2001. [16] Karna SP. (Ed.), Electronic and Nonlinear Optical Materials:  The Role of Theory and Modeling. J. Phys. Chem. A. 104: 4671-4673; 2000. [17] Carcel C, Kaboub L, Gouasmia AK, Fabre JM. Synthesis and redox properties of several new oligoTTF containing functional spacer. Synthetic Metals. 156: 1271-1279; 2006. [18] Binet L, Fabre JM. Synthesis of New Functionalized π-Electron Donors: Primary Hydroxy and Primary Amino Multisulfur Tetrathiafulvalenes. Synthesis. 10: 1179 -1184; 1997. [19] Blanchard P, Salle M, Duguay G, Jubault M, Gorgues A. A simple 1,5 → 1,3-diketone rearrangement. Tetrahedron Lett. 33: 2685-2688; 1992. [20] Moore AJ, Bryce MR, Batsanov AS, Cole JC, Howard JAK. Functionalised Trimethyltetrathiafulvalene (TriMe-TTF) Derivatives via Reactions of Trimethyl- tetrathiafulvalenyllithium with Electrophiles: X-ray Crystal Structures of Benzoyl-TriMe-TTF and Benzoylthio-TriMe-TTF. Synthesis. 6: 675-682; 1995. [21] Heuze K, Fourmigue M, Batail P. The crystal chemistry of amide-functionalized ethylenedithio- tetrathiafulvalenes: EDT-TTF-CONRR′ (R, R′ = H, Me). J. Mater. Chem. 9: 2373-2379; 1999. [22] Heuze K, Meziere C, Fourmigue M, Batail P, Coulon C, Canadell E, Auban-Senzier P, Jerome D. Directing the Structures and Collective Electronic Properties of Organic Conductors: The Interplay of π-Overlap Interactions and Hydrogen Bonds. Chem. Eur. J. 5: 2971; 1999. [23] Heuze K, Fourmigue M, Batail P, Canadell E, Auban-Senzier P. An Efficient, Redox-Enhanced Pair of Hydrogen-Bond Tweezers for Chloride Anion Recognition, a Key Synthon in the Construction of a Novel Type of Organic Metal based on the Secondary Amide-Functionalized Ethylenedithiotetrathiafulvalene, β-(EDT-TTF-CONHMe)2[Cl·H2O]. Chem. Mater. 12: 1898-1904; 2000. [24] Politzer P, Laurence PR, Jayasuriya K. Molecular electrostatic potentials: an effective tool for the elucidation of biochemical phenomena, in: J. McKinney (Ed.), Structure Activity Correlation in Mechanism Studies and Predictive Toxicology, Environ. Health Perspect. 61: 191-202; 1985. [25] Politzer P, Lane P. A computational study of some nitrofluoromethanes. Struct. Chem. 1: 159-164; 1990. [26] Scrocco E., Tomasi J., Electronic Molecular Structure, Reactivity and Intermolecular Forces: An Euristic Interpretation by Means of Electrostatic Molecular Potentials. Adv. Quantum Chem. 11: 115- 193; 1979. [27] Luque FJ, Lopez JM, Orozco M. Perspective on “electrostatic interactions of a solute with a American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 29, No 1, pp 308-326 325 continuum. A direct utilization of ab initio molecular potentials for the prevision of solvent effects”, Theor. Chem. Acc. 103: 343-345; 2000. [28] Politzer P, Truhlar DG. Chemical Applications of Atomic and Molecular Electrostatic Potentials, Plenum Press, New York, 1981. [29] Bader RFW. A quantum theory of molecular structure and its applications, Chem. Rev. 91: 893-928; 1990. [30] Murray JS, Sen K. Molecular Electrostatic Potentials. Concepts and Applications, Elsevier, Amsterdam, 1996. [31] Seminario JM. Recent Development and Applications of Modern Density Functional Theory. Elsevier. 4: 800-806; 1996. [32] Yesilkayanak T, Binzet G, Mehmet Emen F, Florke U, Kulcu N, Arslan H. Eur. J. Chem. 1: 1-5; 2010. [33] Belletete M., Morin J.F., Leclerc M., Durocher G., A Theoretical, Spectroscopic, and Photophysical Study of 2,7-Carbazolenevinylene-Based Conjugated Derivatives. J. Phys. Chem. A. 109: 6953-6959; 2005. [34] Zhenming D, Heping S, Yufang L, Diansheng L, Bo L. Experimental and theoretical study of 10- methoxy-2-phenylbenzo[h]quinoline. Spectrochim. Acta A. 78: 1143-1148; 2011. [35] Parr RG, Szentpaly LV, Liu SJ. Electrophilicity Index. Am. Chem. Soc. 121: 1922-1924; 1999. [36] Chaltraj PK, Maiti B, Sarbar UJ. Philicity:  A Unified Treatment of Chemical Reactivity and Selectivity. J. Phys. Chem. A. 107: 4973-4975; 2003. [37] Parr RG,Donnelly RA, Levy M, Palke WE. Am. Chem. Soc. 68: 3801-3807; 1978. [38] Puzyn T, Leszczynski J, Cronin MTD. Recent Advances in QSAR Studies, Springer, New York, NY, USA, 2010. 30-41. [39] Garrido AP, Helguera AM, Guillén AA, Cordeiro MNDS, Escudero AG. Convenient QSAR model for predicting the complexation of structurally diverse compounds with β-cyclodextrins. Bioorgan. Med. Chem. 17: 896-904; 2009. [40] Parthasarathi R, Padmanabhan J, Subramanian V, Sarkar U, Maiti B, Chattraj PK. Toxicity analysis of benzidine through chemical reactivity and selectivity profiles: a DFT approach. Int. Electron. J. Mol. Des. 2: 798-813; 2003. [41] Srivastava A, Rawat P, Tandon P, Singh RN. A computational study on conformational geometries, chemical reactivity and inhibitor property of an alkaloid bicuculline with γ-aminobutyric acid (GABA) by DFT. Comp. Theor. Chem. 993: 80-89; 2012. [42] Singh RN, Baboo V, Rawat P, Kumar A, Verma D. Molecular structure, spectral studies, intra and intermolecular interactions analyses in a novel ethyl 4-[3-(2-chloro-phenyl)-acryloyl]-3,5-dimethyl-1H- pyrrole-2-carboxylate and its dimer: A combined DFT and AIM approach. Spectrochim. Acta Part A. 94: 288-301; 2012. [43] Singh RN, Kumar A, Tiwari RK, Rawat P, Manohar R. Synthesis, molecular structure, and spectral analyses of ethyl-4-[(2,4-dinitrophenyl)-hydrazonomethyl]-3,5-dimethyl-1H-pyrrole-2-carboxylate . Struct. Chem. 24: 713-724; 2013. [44] Schwenke DW, Truhlar DG. Systematic study of basis set superposition errors in the calculated interaction energy of two HF molecules. J. Chem. Phys. 82: 2418-2426; 1985. American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2017) Volume 29, No 1, pp 308-326 326 [45] Gutowski M, RakPawel J, Blazejowski D. Theoretical Studies on the Geometry, Thermochemistry, Vibrational Spectroscopy, and Charge Distribution in TiX62- (X = F, Cl, Br, I). Coulombic Energy in hexahalogenotitanate Lattices. J. Chem. Phys. 98: 6280-6286; 1994. [46] Shen YR. The Principles of Non-linear Optics, Wiley, New York, 1984. [47] Eaton DF. Nonlinear optical materials. Science. 253: 281-287; 1991. [48] Kolinsky PV. New materials and their characterization for photonic device applications. Opt. Eng. 31: 1676-1684; 1992. [49] Kleinman DA. Nonlinear Dielectric Polarization in Optical Media. Phys. Rev. 126: 1977-1979; 1962. [50] Karna SP, Prasad PN, Dupuis M. Nonlinear optical properties of p-nitroaniline: an ab initio time- dependent coupled perturbed Hartree-Fock study. J. Chem. Phys. 94: 1171-1181; 1991. [51] Adant C, Dupuis M, Bredas JL. Ab initio study of the nonlinear optical properties of urea: Electron correlation and dispersion effects. Int. J. Quantum Chem. 56: 497-507; 2004. Acknowledgments