Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 136 (2015) 852–863

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Spectroscopic and quantum chemical analysis of Isonicotinic acid methyl ester D. Shoba a,b, S. Periandy c, M. Govindarajan d,⇑, P. Gayathri a a

Department of Physics, Periyar Maniammai University, Thanjavur, India Department of Physics, Alpha College of Engineering & Technology, Puducherry, India c Department of Physics, Tagore Arts College, Puducherry, India d Department of Physics, Bharathidasan Government College for Women, Puducherry, India b

h i g h l i g h t s

g r a p h i c a l a b s t r a c t

 Vibrational properties of Isonicotinic

acid methyl ester was examined by FT-IR, FT-Raman and NMR techniques and DFT methods.  The geometrical parameters are in agreement with experimental values.  NLO and NBO analysis of the molecule were studied.  HOMO and LUMO energies, molecular electrostatic potential distribution of the molecule were calculated.

a r t i c l e

i n f o

Article history: Received 2 June 2014 Received in revised form 27 July 2014 Accepted 24 September 2014 Available online 2 October 2014 Keywords: HF DFT Vibrational analysis HOMO LUMO

a b s t r a c t In this present study, an organic compound Isonicotinic acid methyl ester (INAME) was structurally characterized by FTIR, FT-Raman, and NMR and UV spectroscopy. The optimized geometrical parameters and energies of all different and possible conformers of INAME are obtained from Density Functional Theory (DFT) by B3LYP/6-311++G(d,p) method. There are three conformers (SI, SII-1, and SII-2) for this molecule (ground state). The most stable conformer of INAME is SI conformer. The molecular geometry and vibrational frequencies of INAME in the ground state have been calculated by using HF and density functional method (B3LYP) 6-311++G (d,p) basis set. Detailed vibrational spectral analysis has been carried out and assignments of the observed fundamental bands have been proposed on the basis of peak positions and relative intensities. The computed vibrational frequencies were compared with the experimental frequencies, which yield good agreement between observed and calculated frequencies. A study on the electronic properties, such as HOMO and LUMO energies were performed by time independent DFT approach. Besides, molecular electrostatic potential (MEP) and thermodynamic properties were performed. The electric dipole moment (l) and first hyper polarizability (b) values of the investigated molecule were computed using ab initio quantum mechanical calculations. The calculated results show that the INAME molecule may have microscopic nonlinear optical (NLO) behavior with non zero values. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by gauge independent atomic orbital (GIAO) method. Crown Copyright Ó 2014 Published by Elsevier B.V. All rights reserved.

⇑ Corresponding author. Tel.: +91 9443525988. E-mail address: [email protected] (M. Govindarajan). http://dx.doi.org/10.1016/j.saa.2014.09.104 1386-1425/Crown Copyright Ó 2014 Published by Elsevier B.V. All rights reserved.

D. Shoba et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 136 (2015) 852–863

Introduction Isonicotinic acid methyl ester (INAME) is a natural heterocyclic aromatic organic compound. It is a methyl acetate substituted derivative of pyridine. It is also called as methyl; 4-pyridylacetate with molecular formula C8H9NO2 has been isolated from the basic fraction of coal tar and from bone oil. Methyl pyridines have been used for synthesis of polymers with thermal and fire resistance properties. It has been detected in waste water from oil shale processing sites and former creosoting facilities. It has been evaluated for use as a food additive owing to its nutty aroma when present in solution at very low concentrations; however the neat solvent has a pungent, noxious odor [1–5]. INAME is weakly nucleophilic, due to the steric effects of the two methyl groups on the ring nitrogen. Pyridine acid and its derivatives have biological activities. Many drugs found with pyridine compounds. Bromopyridine find wide application in pharmacological industry and in chemical laboratories. Therefore, the spectral and vibrational analysis of substituted pyridine has been the subject of several investigations. Chattopadhyay et al. have been studied the surface-enhanced Raman spectroscopy of 2,5-dibromopyridine and 2,6-dibromopyridine. Halogen substituted pyridine compounds were studied by Green et al. [6–12]. The molecule under study is an isomer of nicotinic. Isonicotinoyl hydrazide (Isoniazid) is one of the anti-tuberculosis drugs and used to kill the mycobacterium tuberculosis. Isonicotinoyl hydrazone derivatives containing heterocyclic moiety have found. It is also used in manufacturing pharmaceuticals and agrochemicals. Niacin acts to reduce plasma cholesterol as a vasodilator and to treat pellagra and also is used for the Prophylaxis. Many substituted pyridines are involved in bioactivities with applications in pharmaceutical drugs and agricultural products (pyridine derivatives act as anesthetic agents, drugs for certain brain diseases, and drugs for treating neuronal damage caused by stroke. Nicotinic acid and its derivatives have biological activities; have been studies extensively over the past decade. The structure of many of the complexes that have been reported show nicotinic acid and its derivatives acting as bridging ligands through the carboxylate group and pyridyl N atom [13]. Nicotinic acid and its complexes with different metals were thoroughly investigated in different methods [14,15]. Extensive experimental and theoretical investigations have focused on elucidating the structure and normal vibrations of nicotinic acid derivatives. Vibrational assignment based FT-IR and Raman spectra and theoretical DFT calculations have been studied for nicotinic and isonicotininc acids [16]. Karaback and Kurt [17] investigated vibrational modes of 6-chloro nicotinic acid by both experimental and theoretical methods. Nagabalasubramanian et al. [18] investigated conformational stability and vibrational modes of nicotinic acid ethyl ester using both experimental and theoretical methods. Sala et al. [19] investigated vibrational modes of nicotinic acid by both experimental and theoretical methods; however, literature survey reveals that to the best of our knowledge, neither quantum chemical calculations nor the vibrational spectra of Isonicotinic acid methyl ester have been reported, as yet. Therefore the present investigation was under taken to study the vibrational spectra of this molecule completely and to identify the various modes with greater wave number accuracy. The interaction energies, NMR spectral analysis, molecular electrostatic potential, thermodynamic and nonlinear optical properties of the title compound were investigated at the B3LYP/6-311++G (d,p) level. In general, the DFT methods yield sufficiently good and consistent results at moderate computational costs. Due to some systematic errors, such as the neglect of anharmonicity and electron correlations, the calculated frequencies are scaled to

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compensate to the approximate treatment of electron correlation for basis set deficiencies and for anharmonicity effects. Experimental details The spectra of Isonicotinic acid methyl ester was purchased from spectral library of Sigma–Aldrich Chemicals, USA. The FT-IR spectrum of the compound was recorded in Perkin-Elmer 180 Spectrometer in the range of 4000–400 cm1. The spectral resolution is ±2 cm1. The FT-Raman spectrum of the compound was also recorded in the same instrument with FRA 106 Raman module equipped with Nd: YAG laser source operating at 1.064 lm line widths with 200 mW powers. The spectra were recorded with scanning speed of 30 cm1 min1 of spectral width 2 cm1. The frequencies of all sharp bands are accurate to ±1 cm1. Quantum chemical calculations The entire quantum chemical calculations have been performed at HF and DFT (B3LYP) methods using the Gaussian 03W program [20]. The optimized geometrical parameters have been evaluated for the calculations of vibrational frequencies at different levels. The computed vibrational modes do not contain any imaginary frequency. Thus, the structures obtained are real minima on the potential energy surface. As a result, the vibrational calculated frequencies, reduced masses, force constants, infrared intensities, Raman activities and depolarization ratios are obtained. In order to improve the calculated values in agreement with the experimental values, it is necessary to scale down the calculated harmonic frequencies. Hence, the vibrational frequencies are scaled using 0.906 for HF and 0.953 used for B3LYP methods [21,22]. After scaling the calculated frequencies, the deviation from the observed values are less than 10 cm1 with a few exceptions. Gauss view program [23] has been considered to get visual animation and for the verification of the normal modes assignment. Results and discussion Potential energy surface (PES) scan, conformational isomers The INAME has one substituent group (carboxyl group) attached to the pyridine ring and methoxy group. The carboxyl group was chosen to investigate the possible conformers of the molecule under investigation. In order to describe conformational flexibility of the title molecule, the energy profile as a function of CACACAO torsion angle was achieved with AM1 method (Fig. 1). All the geometrical parameters were simultaneously relaxed during the calculations while the CACACAO torsional angle was varied in steps of 10°. As can be seen from Fig. 1, the local minima at 0° (or 360°) and 180° were obtained for S1 (C1) and S2 (C1 and Cs) conformers, respectively, for T(CACACAO). This result shows that INAME molecule has three possible structures; depend on the positions of the carbon atom bonded to oxygen and symmetry, whether it is directed away from or toward the ring. The resulted potential energy curve depicted in Fig. 1 shows S1 (C1) form for minimum energy. In this study, calculations were done for two conformers (S1 and S2) of title molecule, however, tables and figures were prepared only for the most stable conformer S1(C1 form). Geometrical analysis The molecular geometry states the position of the atoms in terms of bond lengths, bond angles and dihedral angles with

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The CACAC bond angles are calculated 118.5° which are smaller hexagonal angle of 120° for studied molecule. But CACAN bond angle found to be bigger than 3° hexagonal angles similar values found to be other pyridine derivatives. The symmetry of the benzene ring is disturbed to a small extent and is evident by the CACAC and CANAC angles. The value of bond angle calculated by HF and B3LYP are having excellent agreement with experimental values. FT-IR and FT-RAMAN spectral analysis

Fig. 1. PES scan for the selected degree, T(C–C–C–O) torsional freedom.

respect to an origin atom. The theoretical possible optimized geometric structures with atoms numbering of INAME are shown in Fig. 2. Molecular structure INAME is shown in Fig. 2 (S1) with minimum energy 476.27971881 a.u. as stable conformer. 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. The optimized geometrical bond lengths and bond angles of this compound are calculated by HF and DFT methods with 6-311++G(d,p) are listed in Table 1, along with available experimental data. All the CAC band lengths except C3AC11 in HF/6-311G++(d,p) is 1.38 where as in B3LYP is 1.39 Å which are good agreement with experimental value. The bond length C3AC11 at substitution is 1.49 Å in all the basis sets. The average computed bond lengths CAN and CAH in pyridine ring are 1.33 Å and 1.08 Å where as in methyl group CAH is 1.09 Å. The experimental values of CAN bond length good fit with DFT values. All calculated ring CAH bond lengths in HF and DFT are lesser than substituted methyl group CAH. The C1AC2, C4AC5 and C3AC4 bond lengths computed with HF within 1% error and those at B3LYP/6-311++G(d,p) are in good agreement with experimental data [24]. The calculated CAC, CAN, CAO C@O and CAH bond length value of title compound were found to good agreement with literature.

The maximum number of potentially active observable fundamentals of a non-linear molecule which contains N atoms is equal to (3N-6), apart from three translational and three rotational degrees of freedom [25]. The INAME consists of 17 atoms and belongs to C1 point group symmetry hence the number of normal modes of vibrations for this molecule has 45 normal modes of vibrations. 30 Modes of vibrations are in-plane and remaining 15 is out-of-plane bending vibrations. The bands that belongs to the in-plane modes are represented as A0 while the out-of-plane modes A00 . Thus the 39 normal modes of vibrations are distributed as Vib = 30 A0 + 15 A00 . All the 45 fundamental vibrations are active both in Raman scattering and in IR absorption. The observed and simulated infrared and Raman spectra of INAME is shown in Figs 3 and 4 respectively. The observed and scaled theoretical frequencies using HF and DFT (B3LYP) with 6-311++G(d,p) basis sets are listed in Table 2. Carbon–Hydrogen vibration The hetero aromatic organic compounds commonly exhibit multiple bands in the region 3100–3000 cm1 due to CAH stretching vibrations [26]. In the title molecule, there are four hydrogen atom surrounded by pyridine ring hence four CAH stretching vibration is possible. The C-H stretching has been assigned at 3075 and 3025 cm1 in FTRaman spectrum with strong and medium intensities and at 3065 and 3030 cm1 in FTIR spectrum with medium intensities. The computed scaled values by B3LYP/6311++G(d,p) level are presented at 3079, 3071, 3027 and 3026 cm1 coincide well with the literature value. The CAH in-plane bending vibrations normally occur as a number of strong to weak intensity sharp bands in the region 1300–1000 cm1 [27]. The bands for CAH in-plane bending vibrations of the title compound identified at 1290, 1190, 1160 and 1110 cm1. The CAH out-of-plane bending vibrations are strongly coupled

Fig. 2. The theoretical possible optimized geometric structures with atoms numbering of Isonicotinic acid methyl ester.

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D. Shoba et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 136 (2015) 852–863 Table 1 Optimized geometrical parameters of Isonicotinic acid methyl ester. Parameters Bond length C1H7 C2H8 C4H9 C5H10 C14H15 C14H16 C14H17 O13C11 N6C1 N6C5 C2C1 C3C4 C4C5 O12C11 C11C3 O12C14 Bond angle C3C4C5 H7C1N6 H8C2C1 H9C4C5 H10C5N6 H15C14H17 H16C14H15 H17C14H16 O13C11O12 C1N6C5 a

B3LYP/6-311++G(d,p)

HF/6-311++G(d,p)

Expta

1.0861 1.0816 1.0826 1.0860 1.0875 1.0906 1.0906 1.2084 1.3363 1.3372 1.3932 1.3954 1.3920 1.3467 1.4962 1.4406

1.0760 1.0720 1.0727 1.0759 1.0791 1.0814 1.0814 1.1843 1.3185 1.3201 1.3857 1.3846 1.3840 1.3168 1.4988 1.4190

– – – – – – – 1.253 1.346 1.346 1.393 1.393 1.393 1.260 1.503 –

118.5 116.1 120.8 121.4 116.1 110.7 110.7 109.3 123.6 117.4

118.2 116.4 120.6 121.2 116.4 110.5 110.5 109.4 123.8 118.0

118.6 – – – – – – – 121.0 117.5

Parameters Bond angle C2C1N6 C4C5N6 O12C11C3 C11C3C4 C14O12C11 Dihedral angle H7C1N6C5 H8C2C1N6 H9C4C5N6 H10C5N6C1 H15C14O12C11 H16C14O12C11 H17C14O12C11 C1N6C5C4 C2C1N6C5 C3C4C5N6 O12C11C3C2 C14O12C11C3 O13C3O12C11 C11C2C4C3

B3LYP/6-311++G(d,p)

HF/6-311++G(d,p)

Expta

123.7 123.6 112.3 118.6 115.9

123.5 123.4 112.8 118.7 117.4

123.1 123.1 – – –

180.0 180.0 180.0 180.0 180.0 60.4 60.4 0.0 0.0 0.0 0.0 180.0 0.0 0.0

180.0 180.0 180.0 180.0 180.0 60.6 60.6 0.0 0.0 0.0 0.0 180.0 0.0 0.0

Ref. [24].

Fig. 3. Experimental and simulated Infrared spectra of Isonicotinic acid methyl ester.

Fig. 4. Experimental and simulated Raman spectra of Isonicotinic acid methyl ester.

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Table 2 Experimental and theoretical wavenumbers with vibrational assignments of INAME. No

Experimentala IR

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. a b

HF 6-311++G(d,p) Raman

Unscaled

Scaled

Unscaled

Scaled

IIR

SRaman

3075 vs

3385 3378 3332 3329 3309 3288 3209 1971 1797 1757 1662 1622 1611 1608 1552 1462 1437 1335 1332 1286 1250 1240 1170 1143 1122 1097 1091 1081 989 965 918 857 783 740 730 516 515 439 376 348 224 173 172 116 54

3069 3063 3022 3018 3001 2981 2909 1787 1629 1593 1507 1470 1461 1458 1407 1326 1303 1211 1208 1166 1133 1124 1061 1036 1017 995 989 980 896 875 832 777 710 671 661 468 467 398 341 315 203 157 156 106 49

3214 3205 3160 3159 3155 3126 3052 1777 1632 1602 1520 1497 1482 1471 1438 1350 1293 1277 1238 1212 1171 1139 1102 1088 1011 1008 992 986 900 869 839 772 722 689 681 480 469 387 353 320 208 160 129 106 49

3079 3071 3027 3026 3022 2995 2924 1703 1605 1575 1494 1471 1457 1446 1414 1327 1271 1255 1217 1192 1151 1120 1083 1069 994 990 975 969 884 854 825 759 710 677 670 472 461 381 347 315 205 158 127 104 49

1.92 2.52 11.10 8.45 27.83 16.49 31.89 255.69 6.20 25.44 2.50 9.99 10.06 20.16 28.12 14.42 370.00 68.51 14.82 39.05 0.81 105.86 6.34 19.11 3.78 0.07 0.57 19.41 0.35 10.99 5.50 28.64 27.60 18.90 1.46 3.91 4.42 0.00 0.74 18.66 10.14 0.68 0.13 0.13 1.14

90.43 88.35 86.48 119.55 107.96 53.07 172.35 54.53 50.80 2.57 4.81 7.12 12.41 1.92 1.62 3.92 44.61 11.83 9.48 1.87 2.99 15.34 0.61 2.43 33.46 0.03 0.07 4.42 0.04 1.24 12.76 0.08 0.76 2.22 7.26 0.92 0.34 0.04 4.72 0.40 0.70 0.15 1.22 0.13 1.17

3065 m 3030 m 3025 m 3001vw 2920vw 1710 vs 1605 m 1570s 1495w

1495w 1475vw 1455vw

1445s 1410s 1330 m 1275s 1245vw 1215 m 1195 m 1150vw 1120 m 1080vw 1065 m 995 m

Vibrational assignmentb

B3LYP 6-311++G(d,p)

1120 m

990s 975 m 970vw 885vw 855 m 825 m 760s 710s 675vs 669vw 470vw 460vw 380vw 350vs 210 m

cCH cCH cCH cCH cCH (CH3) cCH (CH3) cCH (CH3) cC@O cC@C cC@C cCN cCC cC-C cC-O bCH3

asym. in plane

cC-C bCH3

sym. bending

cCAN cCAO bHCH bHCH bHCH bHCH bCCC uCH uCH3 rocking uCH uCH uCH bCCC bC@O bCCN bCO CACH3 wagging bCO uCH uC@O uCCC uCO uCO uCCC uCNC uCCC uCCN uCH3 torsion

s: strong; vs: very strong; m: medium; w: weak; vw: very weak. c: stretching; b: in-plane bending; u: out-of-plane bending; IIR: IR intensity, SRaman: Raman scattering activity.

vibrations and normally observed in the region 950–809 cm1 [28]. In the present case, the bands are identified at 995, 975, 970 and 885 cm1 for CAH out-of-plane bending. Except last band, the assigned frequencies are found to be out of their characteristic regions. Methyl group vibration The compounds under investigation possess a CH3 group substituted to Carboxylate ester. For the assignments of CH3 group frequencies one can expect that nine fundamentals can be associated to CH3 group. The CAH stretching is at lower frequencies than those of the aromatic ring. Usually the symmetrical bands are sharper than the asymmetrical bands. Methyl group vibrations are generally referred to as electron-donating substituent in the aromatic rings system, the asymmetric CAH stretching mode of CH3 is expected around 2980 cm1 and CH3 symmetric stretching is expected at 2870 cm1 [29–32]. In INAME, the modes appear at 3001 and 2920 (CH3 asymmetric stretching) are assigned stretching of CAH in CH3 group. The theoretically scaled values by HF and B3LYP/6-311++G(d,p) method at 3000, 2981 2909 in

HF and 3022, 2995 and 2924 cm1 in B3LYP are in good agreement with the experimental values. Except one, remaining two vibrations are having very weak intensities in Raman spectrum. In the present investigation, the bands at 1410 and 1275 cm1 in FT-IR with strong intensities are observed as CH3 asymmetric deformation and symmetric deformation vibrations for INAME. The methyl rocking and wagging modes of vibrations are observed at 990 cm1 and 675 cm1 in Raman and infrared spectrum. In this study, CACH3 stretching vibrations are observed at 840 and 730 cm1 in FT-Raman. The torsional modes appear at in the low-wavenumber regions. In the present case, the computed values are presented at 49 cm1 in HF and B3LYP. Carbon–Carbon vibration C@C stretching vibrations are assigned in the region 1650–1400 cm1 [33,34]. Most of the ring modes are altered by the substitution to aromatic ring. Generally the C@C stretching vibrations in aromatic compounds form the strong bands. For the present molecule two C@C vibrations in the ring are observed at 1605 and 1570 cm1. These two vibrations are appeared in FTIR

D. Shoba et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 136 (2015) 852–863

spectrum with medium and strong intensities. All bands are observed in the expected range. The other three CAC vibrations are appeared at 1455, 1445 and 1330 cm1. The theoretically computed values are at 1461, 1458 and 1327 cm1 by B3LYP/6311++G(d,p) method. The values show excellent agreement with experimental data. Two bands at 1065 and 855 cm81 are assigned to CACAC in-plane bending vibrations in FTIR with medium intensities. The CACAC out-of-plane bending vibrations are observed at 370 and 210 cm1 in INAME respectively. Carbon–Nitrogen vibration CAN vibrations are mixed with several other bands and so it is more difficult to identify in a possible region. Silverstein [35] assigned CAN stretching absorption in the region 1382–1266 cm1 for aromatic amines. In 2-formylpyridine the bands observed at 1569 and 1469 cm1 is assigned to be due to C@N stretching [36]. In the present work, the bands observed at 1495 cm1 in FT-IR spectrum have been assigned to C@N and CAN stretching vibrations observed at 1245 cm1 respectively. It is observed that C@N is within the range, whereas the CAN occurred less than 26 cm1 than the literature. This is due to the effect of substitution. The theoretically calculated values of C@N and CAN stretching vibrations are observed at 1494 and 1255 cm1 respectively by B3LYP/6-311++G(d,p) method. The CCN in-plane bending is observed at 760 cm1 in FTIR and theoretically computed scaled B3LYP 6-311++G(d,p) wave number at 759 cm1. Carbon–oxygen vibration The title molecule, C@O is a functional group and the carbonyl stretching frequency has been most extensively studied by infrared spectroscopy [37]. It is a highly polar band and therefore gives rise to an intense infrared absorption band. The carbon–oxygen double band is formed by p–p bonding between carbon and oxygen– intermolecular hydrogen bonding, reduces the frequencies of the C@O stretching absorption to a greater degree than does inter molecular H bonding because of the different electro negative of C and O, the bonding are not equally distributed between two atoms. The loan pair of electrons on oxygen also determines the nature the carbonyl group. The most characteristic feature of carboxylic acids C@O band shows a strong absorption between 1700–1800 cm1 [38]. The C@O stretching bands of carboxylic acids are considerably more intense than ketonic C@O stretching bands. In the present investigation, a very strong band is appeared at 1710 cm1 in FT-IR shows the presence of carboxylic acid. This C@O vibration appears in the expected range shows that it is not affected by other vibrations. The theoretically computed frequency by B3LYP method is presented at 1703 cm1 respectively, which gives the strong support to the experimental data. The CAO stretching vibrations are assigned at 1445 and 1215 cm1 in FTIR and FT-Raman spectra and the computed values are presented at 1446 and 1217 cm1 by B3LYP method. The medium and strong bands in FTIR spectrum at 825 and 710 cm1 are assigned to in-plane bending of C@O and C-O vibrations. The out-of-plane vibrations are assigned at 460 and 350 cm1.

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LUMO determines the kinetic stability, chemical hardness–softness of a molecule [42,43]. The energy gap of HOMO–LUMO explains the eventual charge transfer interaction within the molecule, which influences the biological activity of the molecule. Furthermore, it is going from the gas phase to the solvent phase, the decreasing value of the energy gap. The plots of the HOMO and LUMO orbitals are computed by B3LYP/6-311++G(d,p) level for INAME, nicotic acid and pyridine molecules are illustrated in Fig. 5 (in gas). HOMO–LUMO gap is very least in nicotic acid. The HOMO figs of all three molecules are almost same. In LUMO figs of three molecules is contradiction to HOMO Fig. 5. The HOMO–LUMO transition implies an electron density transfer from the pyridine ring to the CO through the CC groups. The energy gap of INAME, nicotic acid and pyridine were calculated by using B3LYP/6-311++G(d,p) basis set are 5.4447 eV, 4.9519 eV and 5.8496 eV and reflects the chemical activity of the molecule. The soft molecules are more polarizable than the hard ones because they need small energy to excitation. In order to evaluate the energetic behavior of the title compound, we carried out calculations in DMSO, chloroform and gas phase. The energies of four important molecular orbitals of INAME, the second highest and highest occupied MO’s (HOMO and HOMO1), the lowest and the second lowest unoccupied MO’s (LUMO and LUMO+1) were calculated using B3LYP/6-311++G(d,p) and are presented in Table 3. The 3D plots of HOMO and LUMO orbitals computed at B3LYP level for INAME, nicotic acid and pyridine molecules (in gas phase) are illustrated in Fig. 5. It is clear from the figure that, while the HOMO is localized on almost the whole molecule, LUMO is especially localized on the ring. Both the HOMOs and the LUMOs are mostly-anti-bonding type orbitals. The calculated energies of the HOMO are 7.5005, 7.4951 and 7.4406 eV in gas phase, DMSO and chloroform, respectively. Similarly, the LUMO energies are 2.0558, 1.4993 and 2.0346 eV. The energy gap between HOMO and LUMO indicates the molecular chemical stability. In this molecule, the value of energy separation between the HOMO and LUMO are 5.447, 5.996 and 5.4061 eV in gas phase, DMSO and chloroform, respectively. The electronic properties of the molecules are calculated from the total energies and the Koopmans’ theorem. The ionization potential is determined from the energy difference between the energy of the compound derived from

Frontier molecular orbitals (FMOs) The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) represent the ability to denote or accept an electron [39,40]. These orbitals are named as frontier molecular orbitals (FMO). The FMO plays an important role in optical and electric properties as well as in quantum chemistry and UV–Vis. Spectra [41]. The HOMO represents the ability to donate an electron, LUMO as an electron acceptor represents the ability to obtain an electron. The energy gap between HOMO and

Fig. 5. Energies for the HOMO and LUMO Isonicotinic acid methyl ester, nicotinic acid and pyridine.

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absorption spectra of title molecule were computed in gas, DMSO and chloroform. The excitation energies, absorbance and oscillator strengths for the INAME at the optimized geometry were obtained by using the B3LYP/6-311++G(d,p) method. The predicted UV spectra results were depicted in Table 4 such as absorption wavelengths (k), excitation energies (E), oscillator strengths (f). From the TD-DFT calculation, the computed absorption bands are presented at 289.60, 257.20 and 251.43 nm in gas phase and the excitation energy 4.281 ev, 4.820 ev and 4.931 ev. The other theoretical absorption bands are presented at 289.79, 257.28 and 251.68 nm in DMSO and 292.27, 258.53 and 251.45 nm in chloroform phase. From the results it is found that the energy transition due p–p⁄ for the title molecule. The major contribution is also calculated using Gauss sum program, from the result the major contribution obtained for H?L transitions is 99% for the absorption wave length 289.60 nm.

Table 3 Calculated energies values of INAME in solvent DMSO, chloroform and gas phase. D-DFT/B3LYP/6-311++G(d,p)

DMSO

Chloroform

Gas

Etotal (Hartree) EHOMO (eV) ELUMO (eV) DEHOMOLUMO gap (eV) EHOMO1 (eV) ELUMO+1 (eV) DEHOMO1LUMO+1 gap (eV) EHOMO2 (eV) ELUMO+2 (eV) DEHOMO2LUMO+2 gap (eV) Electronegativity, v (eV) Chemical hardness, g (eV) Softness, f (eV)1 Electrophilicity index, w (eV) Dipole moment (Debye)

476.2915 7.4978 2.0547 5.4431 7.6521 0.7861 6.8660 8.2072 0.9802 9.1874 4.7762 2.7215 0.1837 4.1911 2.9578

476.2895 7.4407 2.0346 5.4061 7.6415 0.7733 6.8682 8.1664 1.0014 9.1678 4.7376 2.7030 0.1849 4.1518 2.7881

476.2916 7.5005 2.0558 5.4447 7.6527 0.7870 6.8657 8.2094 0.9791 9.1885 4.7781 2.7223 0.1836 4.1932 2.9666

Natural bond orbital analysis electron-transfer (radical cation) and the respective neutral compound; IP = Ecation  En; IP = EHOMO while the electron affinity is computed from the energy difference between the neutral molecule and the anion molecule: EA = En  Eanion; EA = ELUMO, respectively. The other important quantities such as electro negativity (v), hardness (g), softness (f), and Electrophilicity index (w) were deduced from ionization potential and electron affinity values [44–46].

In order to investigate the intra and inter-molecular interactions, the stabilization energies of the title compound were performed by using second-order perturbation theory. For each donor NBO (i) and acceptor NBO (j), the stabilization energy E(2) associated with electron delocalization between donor and acceptor is estimated as [47,48] 2

Eð2Þ ¼ DEij ¼ qi

IP þ EA Electro negativityðvÞl  v ¼  2 Chemical hardnessðgÞ 

SoftnessðfÞ ¼

where qi is the donor orbital occupancy, ei, ej are diagonal elements (orbital energies) and F(i,j) is the off-diagonal NBO Fock Matrix element. The results of second-order perturbation theory analysis of the Fock Matrix at B3LYP/6-31G++(d,p) level of theory are presented in Table 5. The larger the E(2) value, the more intensive is the interaction between electron donors and electron acceptors, i.e., the more donating tendency from electron donors and electron acceptors, and greater the extent of conjugation of the whole system. In our title molecule, the intramolecular hyper conjugative interactions are formed by orbital overlap among r(CAC), r⁄(CAC), r(CAN), r⁄(CAN), p(CAC), p⁄(CAC) and p⁄(CAN) orbitals. These interactions are observed as increase in electron density (ED) in antibonding CAC orbital that weakens the respective bonds. The intermolecular hyper conjugative interactions of p–p⁄ transition from C1AC2 ? C3AC4 (22.84 kJ mol1), C5AN6 (19.09 kJ mol1); C5AN6 ? C1AC2 (24.99 kJ mol1) C3AC4 (14.98 kJ mol1); C3AC4 ? C1AC2 (18.25 kJ mol1), C5AN6 (26.53 kJ mol1) and C11AO12 (20.35 kJ mol1) and p bonds in pyridine ring leads to strong delocalization. As well as r–r⁄ transition occur from various bonds in our molecule, r(C1AC2), (C1AN6), (C5AN6), (C4AC5), (C11AO12) and (C11AO13) with antibonding r⁄(C2AC3), (C3AC11), (C4AC5), (C3AC4), (C3AC11), (C3AC11) and (C3AC4) and contribution of energies 3.35, 3.62, 2.08, 2.13,3.46, 4.28, 3.02 and 4.80 kJ mol1 respectively. The most interactions energy, related to the resonance in the molecule, electron donating from

IP  EA 2

1 2g

Electrophilicity indexðwÞ ¼

Fði; jÞ ej  ei

l2 2g

The values of electro negativity, chemical hardness, softness, and Electrophilicity index are 4.7781, 2.7235, 0.1835 and 1.6156 eV in gas phase, respectively for the title molecule. The dipole moment in a molecule is another important electronic property. For example, the bigger the dipole moment, the stronger will be the intermolecular interactions. The calculated dipole moment values for the molecules are also given in Table 3. Based on predicted dipole momentValues, it is found that, in going from the gas phase (2.9666 Debye) to the solvent phase (2.7203 Debye), the dipole moment value decreases. UV–Visible spectral analysis The broad absorption bands associated to a strong p–p⁄ and a weak r–r⁄ transition characterize the UV–Vis absorption spectra. Natural bond orbital analysis indicates that molecular orbitals are mainly composed of r and p atomic orbitals. The electronic

Table 4 Theoretical electronic absorption spectra of INAME (absorption wavelength k (nm), excitation energies E (eV) and oscillator strengths (f)) using TD-DFT/B3LYP/6-311++G(d,p) method in gas phase, DMSO and chloroform. Gas

a

DMSO

Chloroform

Gas

k (nm)

E (eV)

(f)

k (nm)

E (eV)

(f)

k (nm)

E (eV)

(f)

Major contributiona

289.60 257.20 251.43

4.2812 4.8205 4.9312

0.0026 0.0000 0.0584

289.79 257.28 251.68

4.2784 4.8190 4.9263

0.0026 0.000 0.0614

292.27 258.53 251.45

4.2421 4.7958 4.9308

0.0026 0.0000 0.0617

H ? L (99%) H2 ? L (97%) H1 ? L (91%)

H: Homo, L: Lumo.

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D. Shoba et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 136 (2015) 852–863 Table 5 Second Order Perturbation theory analysis of Fock Matrix in NBO.

Table 5 (continued)

Donor (i)

Type

ED/e

Acceptor (J)

Type

ED/e

E(2) (kJ mol1)

C1AC2

r

1.9835

C1AN6 C1AH7 C2AC3 C2AH8 C3AC11

r⁄ r⁄ r⁄ r⁄ r⁄

0.017 0.026 0.024 0.016 0.068

1.79 1.10 3.35 1.21 3.62

C1AC2

p

1.6131

C3AC4 C5AN6

p⁄ p⁄

0.353 0.367

22.84 19.09

C1AN6

r

1.9865

C1AC2 C2AH8 C5AN6 C5AH10

r⁄ r⁄ r⁄ r⁄

0.026 0.016 0.017 0.027

2.08 1.67 1.07 2.15

C1AH7

r

1.9809

C2AC3 C2AH8 C5AN6

r⁄ r⁄ r⁄

0.024 0.016 0.017

3.81 0.53 5.25

C2AC3

r

1.9719

C1AC2 C1AH7 C2AH 8 C3AC4 C3AC11 C4AH9 C11AO12

r⁄ r⁄ r⁄ r⁄ r⁄ r⁄ r⁄

0.026 0.026 0.016 0.025 0.068 0.015 0.098

2.81 2.44 1.24 5.18 2.21 2.66 1.84

C2AH8

r

1.9780

C1AC2 C1AN6 C1AH7 C2AC3 C3AC4

r⁄ r⁄ r⁄ r⁄ r⁄

0.026 0.017 0.026 0.024 0.353

0.75 4.05 0.63 0.96 4.62

C3AC4

r

1.9734

C2AC3 C2AH8 C3AC11 C4AC5 C4AH9 C5AH10 C11AO13

r⁄ r⁄ r⁄ r⁄ r⁄ r⁄ r⁄

0.024 0.016 0.068 0.027 0.015 0.027 0.018

5.26 2.42 2.10 2.86 1.29 2.37 1.83

C3AC4

p

1.6313

C1AC2 C5AN6 C11AO13

p⁄ p⁄ p⁄

0.278 0.367 0.249

18.25 26.52 20.35

C3AC11

r

1.9708

C1AC2 C2AC3 C3AC4 C4AC5 C11AO13 O12AC14

r⁄ r⁄ r⁄ r⁄ r⁄ r⁄

0.026 0.024 0.025 0.027 0.018 0.015

2.49 2.17 2.79 1.97 2.33 4.05

C4AC5

r

1.9831

C3AC4 C3AC11 C4AH 9 C5AN6 C5AH10

r⁄ r⁄ r⁄ r⁄ r⁄

0.025 0.068 0.015 0.367 0.027

3.46 4.28 1.18 1.82 1.09

C4AH9

r

1.9785

C2AC3 C3AC4 C4AC 5 C5AN6 C5AH10

r⁄ r⁄ r⁄ r⁄ r⁄

0.024 0.025 0.027 0.017 0.027

4.45 0.91 0.75 4.09 0.63

C5AN6

r

1.9866

C1AN6 C1AH7 C4AC5 C4AH9

r⁄ r⁄ r⁄ r⁄

0.017 0.026 0.027 0.015

1.07 2.13 2.10 1.64

C5AN6

p

1.7013

C1AC2 C3AC4

p⁄ p⁄

0.278 0.353

24.99 14.98

C5AH10

r

1.9807

C1AN6 C3AC4 C4AH9

r⁄ r⁄ r⁄

0.017 0.025 0.015

5.26 3.88 0.57

C11AO12

r

1.9918

C2AC3 C11AO13 C14AH15

r⁄ r⁄ r⁄

0.024 0.018 0.010

1.68 0.64 0.52

r

1.9953

C3AC4 C3AC11 C3AC4 C11AO13

r⁄ r⁄ r⁄ r⁄

0.025 0.068 0.025 0.018

1.23 3.02 4.80 0.69

C11AO13

Donor (i)

Type

ED/e

Acceptor (J)

Type

ED/e

E(2) (kJ mol1)

O12AC14 C14AH15 N6 O12 O12 O13 O13

r r

1.6607 1.9915 1.9994 1.9647 1.7853 1.9785 1.8514

C3AC11 C11AO12 C1AC2 C11AO13 C11AO13 C11AO12 C11AO12

r⁄ r⁄ r⁄ r⁄ r⁄ r⁄ r⁄

0.068 0.098 0.026 0.018 0.249 0.098 0.098

3.02 3.61 9.50 6.83 48.36 1.37 31.67

LP LP(1) LP(2) LP(1) LP(2)

the LP (2) O12 to the antibonding p⁄ (C11AO13) leads to moderate stabilization energy of 48.36 kJAmol1 is shown in Table 5. In addition to, the interaction are calculated at p⁄ (C5AN6), with p⁄ (C1AC2), (C3AC4) and (C11AO13) with (C3AC4) shows enormous stabilization energy of 138.80, 223.42 and 127.26AkJAmol1respectively. Molecular electrostatic potential The molecular electrostatic potential surfaces demonstrate the charge distributions of molecules three dimensionally. This map allows us to visualize variably charged regions of a molecule. Information of the charge distributions can be used to determine how molecules interact with one another and it is also be used to determine the nature of the chemical bond. There is a great deal of intermediary potential energy, the blue region indicate that the electro negative difference is not very great. In a molecule with a great electronegative difference, charge is very polarized, and there are significant differences in electron density in different region of the molecule. This great electro negativity difference leads to regions that are almost entirely red and almost entirely blue. Greater regions of intermediary potential, yellow and green, and smaller or no regions of extreme potential, red and blue, are key indicators of smaller electro negativity. To predict reactive sites of electrophilic and nucleophilic attack for the investigated molecule, MEP at the B3LYP/6-311++G(d,p) optimized geometry was calculated. The negative (red and yellow) regions of MEP were related to electrophilic reactivity and the positive (blue1) regions to nucleophilic reactivity shown in Fig. 6. Negative regions in the studied molecule were found around the oxygen atoms of the carboxylic groups. Also, a negative electrostatic potential region is observed around the N atoms. The elctronegativity of oxygen atom (O12) decreases due to nearest methyl group. But, the other oxygen atom O13 shows more electronegativity due to its atomic environment. The hydrogen atoms in methyl group more positive than ring hydrogen. The same trend is observed in carbon atoms. The observations from contour map show three closed contour maps. It is identified around ring, COOA and methyl groups. The color code of these maps is in the range between 0.04447e to and 0.04447e. According to these calculated results, the MEP map shows that the negative potential sites are on electronegative atoms (O &N atoms) as well as the positive potential sites are around the (H & C atoms). These sites give information about the region from where the compound can have intermolecular interactions. Non linear optical (NLO) effect NLO properties has been of great interest of current research because of its importance in providing the key functions of frequency shifting, optical modulation, optical switching, optical logic, and optical memory for the emerging technologies in areas 1 For interpretation of color in Fig. 6, the reader is referred to the web version of this article.

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D. Shoba et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 136 (2015) 852–863

Fig. 6. Molecular electrostatic potential and contour map of Isonicotinic acid methyl ester.

such as telecommunications, potential applications in modern communication technology, optical signal processing and data storage [49–52]. Non linear effect arise from the interactions of electromagnetic fields in various media to produce new fields altered in phase, frequency, amplitude or other propagation characteristics from incident fields [53]. The first hyperpolarizability b, dipole moment l and polarizability a is calculated using B3LYP/6-311++G(d,p) basis set on the basis of the finite-field approach. The complete equations for calculating the magnitude of total static dipole moment l, the mean polarizability a0, the anisotropy of the polarizability Da and the mean first hyperpolarizability b0, using the x, y, z components from Gaussian09W program output is as follows.

atot ¼

 1 axx þ ayy þ azz 3

i12 1 h Da ¼ pffiffiffi ðaxx  ayy Þ2 þ ðayy  azz Þ2 þ ðazz  axx Þ2 þ 6a2xz þ 6a2xy þ 6a2yz 2 1

hbi ¼ ½ðbxxx þ bxyy þ bxzz Þ2 þ ðbyyy þ byzz þ byxx Þ2 þ ðbzzz þ bzxx þ bzyy Þ2 2

Table 6 The electric dipole moment, polarizability and first hyperpolarizability of INAME.

axx axy ayy axz ayz azz aTotal Da lx ly lz ltotal

a.u

esu (1024)

114.863 1.07498 94.2284 0.00039 0.0038 43.7025 84.2647 63.4399 0.7529 0.5506 3.7E05 0.93257

17.0227 0.1593 13.9646 5.7E05 0.0006 6.4767 12.488 9.4018

bxxx bxxy bxyy byyy bxxz bxyz byyz bxzz byzz bzzz bx by bz btotal

a.u

esu (1033)

130.76 38.2639 13.3822 29.4389 0.0046 0.0044 0.001 35.378 13.0387 0.00324 152.76 80.7382 0.0024 172.784

1129.7 330.573 115.613 254.331 0.0399 0.0378 0.0087 305.64 112.645 0.02799 1319.7 697.521 0.0206 1492.73

In Table 6, the calculated parameters described above and electronic dipole moment li (i = x, y, z) and total dipole moment for title compound were listed. The total dipole moment can be calculated using the following equation. 1

ltot ¼ ðl2x þ l2y þ l2z Þ2 It is well known that the higher values of dipole moment, molecular polarizability, and hyperpolarizability are important for more active NLO properties. The polarizabilities and hyperpolarizability are reported in atomic units (a.u), the calculated values have been converted into electrostatic units (esu) (for a; 1 a.u = 0.1482  1024 esu, for b; 1 a.u = 8.6393  1033 esu). Urea is one of the prototypical molecules used in the study of the NLO properties of molecular systems. Therefore it was used frequently as a threshold value for comparative purposes. The total molecular dipole moment and first order hyperpolarizability are 0.93257 Debye and 1492.733  1033 esu, respectively and are depicted in Table 6. Total dipole moment of title molecule is approximately one and half times lesser than that of urea and first order hyperpolarizability is 4 times greater than that of urea (l and b of urea are 1.3732 Debye and 0.3728  1033 esu) obtained by HF/6-311G++(d,p) method [54]. From the calculated value of b it is found that the title molecule exhibits the NLO activity. NMR spectra analysis The gauge-including atomic orbital (GIAO) 1H and 13C chemical shift calculations of the compound was made by the same method using 6-311++G(d,p) basis set in gas phase and DMSO solution. The theoretical 1H and 13C NMR chemical shifts have been compared with the experimental data of related molecules [55] which are presented in Table 7. The experimental NMR spectra of the INAME molecule chloroform solvent is presented in Fig 7. Aromatic carbons give signals in overlapped areas of the spectrum with chemical shift values from 100 to 150 ppm. In the present investigation, the experimental chemical shift values of aromatic carbons are in the range 125.42–153.67 ppm. On the basis of 13C NMR spectra, in which the ring carbons (C1 and C5) attached to the N atom have bigger chemical shift than the other

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D. Shoba et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 136 (2015) 852–863 Table 7 Experimental and calculated 1H and Atoms

C11 C5 C3 C4 C2

13

C NMR isotropic chemical shifts (ppm) of INAME.

B3LYP Calculated

Corrected

171.077 156.574 141.225 127.729 53.670

165.292 151.359 136.614 123.649 52.503

Expta

Atoms

165.407 150.999 136.958 123.564 52.493

H9 H8 H17 H15

Expta

B3LYP Calculated

Corrected

8.122 7.869 3.894 3.691

8.441 8.171 3.918

8.767 7.825 3.939 – –

Fig. 8. Correlation graph of NMR for Isonicotinic acid methyl ester.

Table 8 Thermodynamic functions of INAME at the B3LYP/6-311++G(d,p) level.

Fig. 7. Experimental 1H and

13

C NMR of Isonicotinic acid methyl ester.

carbon atoms. This shows that C1 and C5 atoms are deshielded than other carbon atoms. The chemical shift value of C14 is smaller than the other aromatic carbons because of the substitution of methyl group. Hence, C14 is highly shielded due the presence of methyl group protons. The computed chemical shift value of C14 is 53.16 ppm. The C11has the chemical shift of 170.18 ppm, which is also in downfield and deshielded. The studied molecule has hydrogen atoms attached to the ring and methyl groups. The chemical shifts calculated for the H atoms of methyl groups are quite low. It may be due to hydrogen atom attached or nearby electron-withdrawing atom or group can increase the shielding. All hydrogen atoms of methyl groups chemical shift values are 4.14 ppm due to the shielding effect. Hydrogen attached to ring are accumulated in the range of 8.11–9.02 ppm. They are in down field, hence deshielded. The correlation graph is drawn between experimental and computed NMR data and is shown in Fig. 8. The linear correlation equation is used to find nearest computed NMR values with experimental values.

T (K)

C (cal mol1 k1)

S (cal mol1 k1)

DH (kcal mol1)

100 150 200 250 300 350 400 450 500 550 600

13.494 17.999 21.749 26.442 30.784 34.466 39.976 42.953 47.182 51.411 54.964

67.985 75.078 81.235 86.126 91.653 97.216 103.237 107.731 113.266 118.800 123.267

1.157 1.487 3.115 5.445 7.084 8.948 10.792 12.795 14.360 16.226 19.656

ranging from 200 to 700 K due to the fact that the molecular vibrational intensities increase with temperature [56]. The correlation equations between heat capacities, entropies, enthalpy changes and temperatures were fitted by quadratic formulas and the corresponding fitting factors (R2) for these thermodynamic properties are 0.9972, 0.9821 and 0.95923 respectively. The corresponding fitting equations are as follows and the correlation graphics of those shows in Fig. 9

C ¼ 2:60586 þ 0:10646T  3:615  105 T 2 ðR2 ¼ 0:9972Þ

Thermodynamic properties

S ¼ 55:64071 þ 0:12836T  3:8088  105 T 2 ðR2 ¼ 0:9821Þ

On the basis of vibrational analysis at B3LYP/6-311G++(d,) level the standard statistical thermodynamic functions: heat capacities (C) entropies (S), and enthalpy changes (DH) for the title compounds were obtained from the theoretical harmonic frequencies and listed in Table 8. From Table 8, it can be observed that these thermodynamic functions are increasing with temperature

DH ¼ 81:7654 þ 0:0192T þ 2:04417  105 T 2 ðR2 ¼ 0:95923Þ All the thermodynamic data supply helpful information for the further study on the INAME. They can be used to compute the other thermodynamic energies according to relationships of thermodynamic functions and estimate directions of chemical

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D. Shoba et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 136 (2015) 852–863

Fig. 10. The Mulliken charge distribution of pyridine, nicotinic acid and Isonicotinic acid methyl ester.

Fig. 9. Correlation graph of themodynamic functions for Isonicotinic acid methyl ester.

reactions according to the second law of thermodynamics in thermo chemical field [57]. Notice: all thermodynamic calculations were done in gas phase and they could not be used in solution.

methyl group in Isonicotinic acid methyl ester. It indicates additional derivates added in the parent molecules make drastic change in the charge. The charges of hydrogen atoms connected to the ring of all three molecules are positive but there is slight variation in magnitude. The oxygen atoms O12 and O13 charge are negative with varying magnitude is observed for both nicotinic acid and Isonicotinic acid methyl ester.

Comparative Mulliken charge analysis The Mulliken population analysis of pyridine, Nicotinic acid and Isonicotinic acid are computed using B3LYP with 6-311++G(d,p) basis set and are listed in Table 9. The comparative graphs of Mulliken atomic charges of three molecules presented in Fig. 10. In the ring carbon atom the Mulliken charge of C3 in substitution position is deviated more with positive value in the nicotinic acid and Isonicotinic acid methyl ester, whereas in the pyridine it is more negative in nature. This shows that the substitution of Carboxylate in pyridine alter the charge distribution. Other ring carbon atom having same values in the all three molecules but only there is small variation in their magnitude. The charge of nitrogen atom N6 is high negative value for nicotinic acid compared to Isonicotinic acid methyl ester. This is due the additional substitution of

Table 9 Muliken atomic charge for pyridine, nicotinic acid and isonicotinic acid methyl ester. Pyridine

Nicotinic acid

Isonicotinic acid methyl ester

Atom

Charge

Atom

Charge

Atom

Charge

C1 C2 C3 C4 C5 N6 H7 H8 H9 H10 H11 – – – – – – – –

0.3436 0.0778 0.1889 0.0778 0.3436 0.0976 0.1669 0.1671 0.1585 0.1585 0.1671 – – – – – – – –

C1 C2 C3 C4 C5 N6 H7 H8 H9 H10 C11 O12 O13 H14

0.5341 0.3086 0.3595 0.1540 0.5352 0.1379 0.2076 0.2322 0.2491 0.2057 0.2572 0.3099 0.2665 0.3243

C1 C2 C3 C4 C5 N6 H7 H8 H9 H10 C11 O12 O13 C14 H15 H16 H17

0.0735 0.1303 0.1389 0.1094 0.0706 0.2779 0.1142 0.1187 0.1119 0.1134 0.4548 0.3158 0.3435 0.1218 0.1212 0.1247 0.1247





Conclusion In the present investigation, FT-IR and FT-Raman spectra of INAME are recorded and the observed vibrational frequencies are assigned depending upon their expected region. The hybrid computational calculations are carried out by HF and DFT methods and corresponding results are tabulated. The influences of methyl group and pyridine ring to the vibrational frequencies of the title compound were discussed. Various quantum chemical calculations help us to identify the structural and symmetry properties of the titled molecule. The excellent agreement of the calculated and observed vibrational spectra reveals the advantages of higher basis set for quantum chemical calculations. Furthermore, the thermodynamic and electronic absorption properties of the compounds have been calculated. The correlations between the statistical thermodynamics and temperature are also obtained. It was seen that the heat capacities, entropies and enthalpies increase with the increasing temperature owing to the intensities of the molecular vibrations increase with increasing temperature. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Besides frontier molecular orbitals (FMO), molecular electrostatic potential (MEP) was performed. NLO properties related to polarizability and hyper polarizability was also discussed. 13C and 1H NMR calculations were done using GIAO methods, and the results were compared with closely related molecule. Mulliken atomic charge were also calculated the charges are compared with parent and closely related molecules.

Acknowledgement We are thankful to honorable Vice Chancellor Professor. Dr.N.Ramachandiran, Periyar Maniammai University, Thanjavur and Dr. D.Kumar, Dean Research, Periyar Maniammai University for granting to do this Research work.

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Reference [1] V.M. Chapela, M.J. Percino, C.R. Barbarin, J. Chem. Crystallogr. 33 (2003) 77–83. [2] M.J. Percino, V.M. Chapela, Polym. Mater. Encycl., vol. 9, CRC Press, Boca Raton, 1996. [3] M. Ropars, B. Bloch, French Patent 2 (1974) 261, 296; U.S. Patent 3 S62, 1976. [4] B.P. Malassine, J.C.C. Gautier, S.H. Chevalier, G.R. Berteleau, U.S. Patent 4163, 1979. [5] J. Ratto, C.T. Hamermesh, U.S. Patent 4362, 1982. [6] S. Chattopadhyay, S.K. Brahma, Spectrochim. Acta A 48 (1992) 1789–1793. [7] J.H.S. Green, D.J. Harrison, Spectrochim. Acta 33 (1977) 81–82. [8] T.D. Klots, Spectrochim. Acta 54A (1998) 1481–1498. [9] K.Y. Rajpure, C.H. Bhosale, J. Mater. Chem. Phys. 64 (2000) 70–74. [10] S.P. Jose, S. Mohan, Spectrochim. Acta A 64 (2006) 205–209. [11] V. Krishnakumar, R.J. Xavier, Spectrochim. Acta A 61 (2005) 253–260. [12] N. Sundaraganesan, S. Kalaichelvan, C. Meganathan, B.D. Joshua, J. Cornard, Spectrochim. Acta A 71 (2008) 898–906. [13] S. Gao, J. Liu, L. Huo, Z. Sun, J. Gao, S. Weng Ng, Acta Cryst (2004) m363–m365. [14] C.L. Broadhurst, W.F. Schmidt, J.B. Reeves, M.M. Polansky, K. Gautsdhi, et al., J. Inorg. Biochem. 66 (1997) 119. [15] N.K. Singh, D.K. Singh, et al., Synth., React. Inorg Met. – Org. Chem. 32 (2002) 203. [16] P. Koczon, J.cz. Dobrowolski, W. Lewandowski, A.P. Mazurek, J. Mol. Struct. 655 (2003) 89–95. [17] M. Karaback, M. Kurt, SpectroChim. Acta A 71 (2008) 876–883. [18] P.B. Nagabalasubramanian, Mehmet Karabacak, S. Periandy, J. Mol. Struct. 1017 (2012) 1–13. [19] O. Sala, N.S. Goncalves, L.K. Noda, J. Mol. Struct. 565–566 (2001) 411–416. [20] M.J. Frisch et al., Gaussion 03 Program, Gaussian, Inc., Wallingford, CT, 2004. [21] A. Hakan, A. Öztekin, Int. J. Mol. Sci. 8 (2007) 760–776. [22] A. Nataraj, V. Balachandran, T. Karthick, M. Karabacak, A. Atac, J. Mol. Struct. 1027 (2012) 1–14. [23] R.I. Dennington, T. Keith, J. Millam, K. Eppinnett, W. Hovell, Gauss View Version, 2003. [24] T. Whitfield, L. Zheng, X. Wang, A.J. Jacobson, Solid State Sci. 3 (2001) 829–835. [25] M. Silverstein, G. Clayton Bassles, C. Morril, Spectroscopic Identification of Organic Compounds, John wiley, New York, 1981. [26] V. Krishnakumar, V. Balachandran, T. Chithambarathann, Spectrochim. Acta Part A 62 (2005) 918–925. [27] N. Sundaraganesan, H. Saleem, S. Mohan, M. Ramalingam, V. Sethuraman, Spectrochim. Acta Part A 62 (2005) 740–751. [28] S.J. Singh, S.M. Pandey, Ind. J. Pure Appl. Phys. 12 (1974) 300–304. [29] J. Sponer, P. Hobza, Int. J. Quant. Chem. 57 (1996) 959–970.

863

[30] N.B. Colthup, L.H. Daly, S.E. Wiberley, Introduction to Infrared and Raman Spectroscopy, Academic Press, New York, 1964. [31] G. Socrates, Infrared and Raman Characteristic Group Frequencies –Tables and Charts, third ed., Wiley, New York, 2001. [32] F.R. Dollish, W.G. Fateley, F.F. Bentley, Characteristic Raman Frequencies of Organic Compounds, Wiley, New York, 1997. [33] V. Krishnakumar, R.J. Xavier, Ind. J. Pure Appl. Phys. 41 (2003) 95–98. [34] N.P. Singh, R.V. Yadav, Ind. J. Phys. B 75 (4) (2001) 347–355. [35] M. Silverstein, G.C. Basseler, C. Morill, Spectrometric Identification of Organic Compounds, Wiley, New York, 1981. [36] Y. Umar, Spectrochim. Acta Part A 71 (2009) 1907–1913. [37] R.A. Yadav, I.S. Sing, Ind. J. Pure. Appl. Phys. 23 (1985) 626. [38] E.A. Velcheva, L.I. Daskalova, I.G. Binev, Bulg. Chem. Commun. 36 (2004) 230. [39] S. Subashchandrabose, A.R. Krishnan, H. Saleem, V. Thanikachalam, G. Manikandan, Y. Erdogdu, J. Mol. Struct. 981 (2010) 59–70. [40] S. Gunasekaran, R.A. Balaji, S. Kumerasan, G. Anand, S. Srinivasan, Can. J. Anal. Sci. Spectrosc. 53 (2008) 149–161. [41] I. Fleming, Frontier Orbitals and Organic Chemical Reactions, Wiley, London, 1976. [42] A.M. Asiri, M. Karabacak, M. Kurt, K.A. Alamry, Spectrochim. Acta A 82 (2011) 444–455. [43] B. Kosar, C. Albayrak, Spectrochim. Acta A 78 (2011) 160–167. [44] W. Kohn, A.D. Becke, R.G. Parr, J. Phys. Chem. 100 (1996) 12974–12980. [45] R.G. Parr, R.G. Pearson, J. Am. Chem. Soc. 105 (1983) 7512–7516. [46] P. Politzer, F.A. Awwad, Theor. Chem. Acc. 99 (1998) 83–87. [47] D.W. Schwenke, D.G. Truhlar, J. Chem. Phys. 82 (1985) 2418–2427. [48] M. Gutowski, G. Chalasinski, J. Chem. Phys. 98 (1993) 4728–4738. [49] C. Andraud, T. Brotin, C. Garcia, F. Pelle, P. Goldner, B. Bigot, A. Collet, J. Am. Chem. Soc. 116 (1994) 2094–2102. [50] V.M. Geskin, C. Lambert, J.L. Bredas, J. Am. Chem. Soc. 125 (2003) 15651– 15658. [51] M. Nakano, H. Fujita, M. Takahata, K. Yamaguchi, J. Am. Chem. Soc. 124 (2002) 9648–9655. [52] D. Sajan, I.H. Joe, V.S. Jayakumar, J. Zaleski, J. Mol. Struct. 785 (2006) 43–53. [53] Y.X. Sun, Q.L. Hao, W.X. Wei, Z.X. Yu, L.D. Lu, X. Wang, Y.S. Wang, J. Mol. Struct.: Theochem. 904 (2009) 74–82. [54] C. Jesintha John, M. Amalanathan, D. Sajan, K. Udaya Lakshimi, I.H. Joe, Spectrochim. Acta 78 A (2011) 264–272. [55] , Spectral Database for Organic Compounds, SDBS. [56] J. BevanOtt, J. Boerio-Goates, Calculations from Statistical Thermodynamics, vol. 5, Academic Press, 2000. p. 589. [57] R. Zhang, B. Dub, G. Sun, Y. Sun, Spectrochim. Acta A 75 (2010) 1115–1124.

Spectroscopic and quantum chemical analysis of Isonicotinic acid methyl ester.

In this present study, an organic compound Isonicotinic acid methyl ester (INAME) was structurally characterized by FTIR, FT-Raman, and NMR and UV spe...
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