Theoretical and experimental investigations on vibrational and structural properties of tolazamide

Journal of Molecular Structure 1095 (2015) 87–95

Contents lists available at ScienceDirect

Journal of Molecular Structure journal homepage: www.elsevier.com/locate/molstruc

Theoretical and experimental investigations on vibrational and structural properties of tolazamide Mustafa Karakaya a,⇑, Yusuf Sert b,c, Mehmet Kürekçi d, Buse Eskiyurt d, Çag˘rı Çırak d a

Department of Energy Systems, Faculty of Engineering & Architecture, Sinop University, Sinop 57000, Turkey Department of Physics, Faculty of Art & Sciences, Bozok University, Yozgat 66100, Turkey c Sorgun Vocational School, Bozok University, Yozgat 66100, Turkey d Department of Physics, Faculty of Art & Sciences, Erzincan University, Erzincan 24100, Turkey b

h i g h l i g h t s  FT-IR and Laser-Raman spectra of tolazamide were recorded in solid phase.  Theoretical harmonic vibrational frequencies and optimized molecular structure were given for the first time.  The complete assignments were performed on the basis of the potential energy distribution (PED).  HOMO–LUMO energies and related molecular properties were evaluated.

a r t i c l e

i n f o

Article history: Received 27 January 2015 Received in revised form 17 April 2015 Accepted 20 April 2015 Available online 30 April 2015 Keywords: Tolazamide FT-IR spectra Raman spectra Hartree–Fock method Density functional theory

a b s t r a c t In this paper, vibrational spectra of tolazamide have been investigated by ab initio techniques in combination with experimental studies. Data on the FT-IR spectra (400–4000 cm 1) and Laser-Raman spectra (100–4000 cm 1) of tolazamide have been obtained in the solid phase. Assignments corresponding to the vibrational frequencies have been found and interpreted by the contribution of the potential energy distributions. The theoretical results are compared X-ray experimental data for this. Structural parameters such as bond lengths and angles, frequencies and intensities regarding Raman and IR spectra of the compound have been computed by density functional theory and Hartree–Fock methods with 6-311G++(d,p) and 6-31G(d) basis sets. They have been observed that the computed vibrational frequencies and optimized structural parameters are consistent with the corresponding experimental results. In addition, the images of frontier molecular orbitals (highest occupied and lowest unoccupied) have been presented and interpreted. Ó 2015 Elsevier B.V. All rights reserved.

Introduction ‘‘Diabetes mellitus’’ is chronic and multifactorial disease analyzed with subheadings such as raised basal metabolic rate, damages in pancreatic beta cells, hyperglycemia. So, diabetes mellitus researches are increasing rapidly on the same rate as the increase of the disease all around the world in recent years. Drugs containing the biguanide and sulfonylurea structures for the purpose of reducing the hyperglycaemia are quite noteworthy in the field of diabetes. Because of the side effects of these drugs, the researches have been also focused on a new class of compounds. Sulfonylureas as the first-generation antidiabetic, such as tolazamide and tolbutamide, are still practiced in the treatment of diabetes but they are ⇑ Corresponding author. Tel.: +90 368 2715516; fax: +90 368 2714152. E-mail address: [email protected] (M. Karakaya). http://dx.doi.org/10.1016/j.molstruc.2015.04.028 0022-2860/Ó 2015 Elsevier B.V. All rights reserved.

less effective than the second-generation antidiabetics such as glipizide and glibenclamide. Besides, compounds with the inclusion of sulfonylurea are known for effective hypoglycemic activity. Such efficacious compounds are generally substituted on the urea groups and benzene rings. Tolazamide is an oral drug that lowers blood glucose in sulfonylurea class. The sulfonylurea derivatives are known to attract the attention on distinguishing biochemical and physical properties [1–13]. We aimed to contribute to the literature by theoretical and experimental analysis on tolazamide due to the interest in sulfonylurea groups in especially pharmaceutical industry. We have also reported a study on structural and vibrational analysis of similar anti-hyperglycemic biomolecules, gliclazide, previously [14]. Although X-ray diffraction method is one of the most frequently applied techniques for structural characterization of pharmaceutical compounds, but the utility of vibrational spectroscopy method

88

M. Karakaya et al. / Journal of Molecular Structure 1095 (2015) 87–95

has gained wide attention, due to its applicability to the shortrange structure of molecular solids; rather than X-ray techniques which are being sensible to the long range order. From another perspective, we could not be reached to work on vibrational and structural characteristics of tolazamide with the help of ab initio calculation methods in literature searches. Therefore, molecular structure, frontier molecular orbitals, vibrational frequencies and related assignments of tolazamide have been investigated in detail by density functional theory (B3LYP exchange–correlation energy functional) and Hartree–Fock (HF) methods with the support of 6-311G++(d,p) and 6-31G(d) levels. Experimental peak data on Raman and FT-IR spectra of the title compounds have been also recorded in this paper. Fig. 1. Optimized structure of tolazamide by density functional theory.

Experimental details Tolazamide sample was purchased from Sigma–Aldrich Co. (St. Louis, MO, USA). Fourier transforms infrared spectroscopic data (400–4000 cm 1) for a KBr disk of tolazamide were recorded by a Pelkin Elmer (Waltham, MA, USA) Spectrum One Fourier transform infrared spectrometer with a resolution of 4 cm 1 at room temperature. The Laser-Raman spectrum data (100–4000 cm 1) were recorded with the help of a spectrometer in specifications of 830 nm laser, Laser power 30 mW, and accumulation 1 and exposure time 10 s. Computational details Optimization steps, structure parameters, vibrational frequencies, infrared intensities, Raman scattering activities and molecular orbital visuals of tolazamide have been obtained by HF and DFT (B3LYP hybrid functional) methods with the 6-311G++(d,p) and 6-31G(d) basis set level. Gaussian 09 computer system [15] has been used for all computations. The values of 0.9051 (HF), 0.9614 (B3LYP) and 0.8929 (HF), 0.9613(B3LYP) for 6-311G++(d,p) and 6-31G(d) basis set levels, respectively, as the scale factors [16] have been used in the computed harmonic frequencies. Vibrational Energy Distribution Analysis (VEDA 4) program [17] has been preferred to identify the stretching, in plane bending, torsional and out-of-plane local modes by potential energy distribution (PED) analysis. The studies involving vibration modes have been enriched with PED analysis by many researchers, previously [18–22]. Results and discussions Tolazamide structure contains 42 atoms. A molecule consisting on N atoms has a total of 3 N degrees freedom, corresponding to the Cartesian coordinates of each atom in the molecule. In a nonlinear molecule, 3 of these degrees belong to the rotational, and 3 to the translational motions of the molecule, and so the remaining corresponds to its vibrational motions. The net number of the vibrational modes is 3 N-6. Therefore, for our molecule, three Cartesian displacements of 42 atoms provide 120 normal vibration modes. The molecule has C1 symmetry. Tolazamide electronic structures defined with atomic numbers after optimization have been presented shown in Fig. 1. The results in Table 1 contain the energies corrected for the zero point energy, dipole moments and frontier molecular orbital energies by different methods and basis set levels for the optimized compounds. Total energy values obtained by the B3LYP method are much lower than the HF method and the optimized geometry with minimal energy has resulted by B3LYP/6-311G++(d,p) level. Because in DFT/B3LYP, some correlation effects are taking into account through the effective exchange–correlation potential (the most stable method). In HF, each electron only sees the average electric field produced by

all the other electrons, while DFT/B3LYP uses a more exact treatment by using functionals to describe the potential environment for each electron. Geometric structure Tolazamide, C14H21N3O3S chemical formula, is an antidiabetic drug. Structure of the title compound consists of p-toly group, urea, sulfonyl amide and azepine group. One of the two N atoms of the urea is bounded to the azepine group while the other is bounded to the sulfonyl group which, in turn, is connected to the p-toly group. The structural parameters as bond lengths and angles resulted by using B3LYP and HF methods, 6-311G++(d,p) and 6-31G(d) basis set levels have been given in Table 2. Structure parameters of tolazamide have been compared with the experimental data from the literature [1]. They have been observed that the computed vibrational frequencies and optimized structural parameters are consistent with the corresponding experimental results. It can be said to be good agreement with the experimental data for the geometric parameters of tolazamide. Although the experimental data are obtained in the solid phase as single crystal for organics, the results of ab initio calculations are for its gas phase. Small mismatches between the structural parameters can be attributed to this situation. B3LYP hybrid functionals with 6-311G++(d,p) level have the highest correlations in both calculations bond lengths and angles when compared with the experimental ones. Vibrational assignments The experimental FT-IR and Laser-Raman spectra of the title compound have been given as Figs. 2 and 3, respectively, by combining theoretical IR and Raman spectra. Harmonic frequencies, IR intensities and Raman activities computed by B3LYP and HF approaches with 6-311G++(d,p) and 6-31G(d) basis sets are given in Table 3. Scale factors have been used in order to increase the correlations between theoretical and observed vibrational frequencies [23]. Also, the vibration modes assignments with the values higher than 10% in PED are situated in Table 3. CAH vibrations CAH stretching vibrations have been commonly observed as multiple weak bands in the region 3100–3000 cm 1 for aromatic structures [24–26]. Tolazamide has substituted aromatic system with four CAH adjacent moieties, stretching modes of C5AH3, C6AH4, C2AH1 and C3AH2, in this work. CAH stretching modes have been observed at 3108 and 3049 cm 1 in FT-IR spectra and 3077 and 3055 cm 1 in Raman spectra. These CAH modes are

89

M. Karakaya et al. / Journal of Molecular Structure 1095 (2015) 87–95 Table 1 Computational values for electronic and zero point energies, dipole moments, HOMO–LUMO energies of tolazamide. Methods B3LYP/6-311G++(d,p) B3LYP/6-31G(d) HF/6-311G++(d,p) HF/6-31G(d)

Energy (hartree/part.) 1334.46592692 1334.17370738 1327.99625932 1327.74183960

Dipole moment (Debye) 5.0709 4.7669 5.3106 5.2220

HOMO energy (a.u.) 0.24400 0.23281 0.36342 0.35836

LUMO energy (a.u.) 0.06113 0.04578 0.03032 0.09242

HOMO–LUMO energies gap (a.u.) 0.18287 0.18703 0.39374 0.45078

Table 2 Calculated geometric parameters of tolazamide. Geometric parameters

Experimental values [1]

Bond lengths (Å) C1AC2 C1AC6 C1AS1 C2AC3 C2AH1 C3AC4 C3AH2 C4AC5 C4AC7 C5AC6 C5AH3 C6AH4 C7AH5 C7AH6 C7AH7 S1AO1 S1AO2 S1AN1 N1AH8 N1AC8 C8AO3 C8AN2 N2AH9 N2AN3 N3AC9 N3AC10 C9AC11 C9AH10 C9AH11 C10AC12 C10AH12 C10AH13 C11AC13 C11AH14 C11AH15 C12AC14 C12AH16 C12AH17 C13AC14 C13AH18 C13AH19 C14AH20 C14AH21

Bond angles (°) C2AC1AC6 C2AC1AS1 C1AC2AC3 C1AC2AH1 C6AC1AS1 C1AC6AC5 C1AC6AH4 C1AS1AO1 C1AS1AO2 C1AS1AN1 C3AC2AH1 C2AC3AC4 C2AC3AH2 C4AC3AH2 C3AC4AC5

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

B3LYP/6-31G(d)

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

HF/6-31G(d)

1.392 1.395 1.794 1.393 1.082 1.398 1.085 1.402 1.508 1.389 1.085 1.083 1.095 1.091 1.093 1.463 1.456 1.693 1.014 1.431 1.210 1.364 1.019 1.402 1.474 1.474 1.531 1.106 1.091 1.535 1.103 1.091 1.537 1.095 1.096 1.541 1.097 1.094 1.538 1.098 1.095 1.095 1.095

1.396 1.397 1.791 1.393 1.084 1.402 1.087 1.403 1.510 1.392 1.087 1.085 1.098 1.094 1.095 1.468 1.461 1.695 1.016 1.431 1.214 1.369 1.021 1.404 1.473 1.473 1.533 1.109 1.094 1.536 1.105 1.093 1.538 1.098 1.098 1.542 1.099 1.097 1.539 1.100 1.098 1.097 1.097

1.381 1.390 1.765 1.387 1.073 1.387 1.075 1.395 1.509 1.378 1.076 1.074 1.086 1.083 1.086 1.425 1.420 1.645 0.998 1.412 1.186 1.351 0.999 1.387 1.461 1.462 1.526 1.096 1.083 1.530 1.092 1.082 1.532 1.087 1.088 1.536 1.089 1.086 1.533 1.090 1.087 1.087 1.086

1.383 1.390 1.765 1.386 1.072 1.387 1.075 1.395 1.510 1.378 1.076 1.074 1.085 1.083 1.085 1.431 1.426 1.650 1.000 1.409 1.190 1.354 1.000 1.388 1.460 1.461 1.527 1.094 1.082 1.531 1.091 1.081 1.533 1.086 1.088 1.536 1.088 1.085 1.534 1.089 1.086 1.087 1.085

R2=

0.9690

0.9677

0.9602

0.9619

120.0 119.6 118.2

121.1 119.7 119.0 120.1 119.1 119.0 120.2 107.8 108.1 106.9 120.9 121.2 119.2 119.6 118.4

121.0 119.8 119.0 120.0 119.2 119.1 120.1 107.8 108.1 106.8 120.9 121.2 119.3 119.5 118.4

120.7 120.1 119.3 120.2 119.3 119.3 120.3 107.9 108.3 107.0 120.5 121.0 119.1 119.8 118.6

120.7 120.1 119.3 120.1 119.2 119.3 120.2 107.8 108.4 106.8 120.5 121.0 119.2 119.8 118.6

1.384 1.360 1.756 1.381 1.374 1.364 1.510 1.367

1.433 1.423 1.656 1.392 1.213 1.322 1.423 1.475 1.466 1.512

1.467

1.522

1.535

1.482

120.4 120.2 109.4 109.2 105.3 122.3

117.4

(continued on next page)

90

M. Karakaya et al. / Journal of Molecular Structure 1095 (2015) 87–95

Table 2 (continued) Geometric parameters

Experimental values [1]

Bond lengths (Å) C3AC4AC7 C5AC4AC7 C4AC5AC6 C4AC5AH3 C4AC7AH5 C4AC7AH6 C4AC7AH7 C6AC5AH3 C5AC6AH4 H5AC7AH6 H5AC7AH7 H6AC7AH7 O1AS1AO2 O1AS1AN1 O2AS1AN1 S1AN1AH8 S1AN1AC8 H8AN1AC8 N1AC8AO3 N1AC8AN2 O3AC8AN2 C8AN2AH9 C8AN2AN3 H9AN2AN3 N2AN3AC9 N2AN3AC10 C9AN3AC10 N3AC9AC11 N3AC9AH10 N3AC9AH11 N3AC10AC12 N3AC10AH12 N3AC10AH13 C11AC9AH10 C11AC9AH11 C9AC11AC13 C9AC11AH14 C9AC11AH15 H10AC9AH11 C12AC10AH12 C12AC10AH13 C10AC12AC14 C10AC12AH16 C10AC12AH17 H12AC10AH13 C13AC11AH14 C13AC11AH15 C11AC13AC14 C11AC13AH18 C11AC13AH19 H14AC11AH15 C14AC12AH16 C14AC12AH17 C12AC14AC13 C12AC14AH20 C12AC14AH21 H16AC12AH17 C14AC13AH18 C14AC13AH19 C13AC14AH20 C13AC14AH21 H18AC13AH19 H20AC14AH21

122.2 120.3 121.8

119.9 109.2 105.3 123.4 122.4 113.5 124.1 121.2 110.2 110.9 115.8 118.1

119.9

113.6

114.5

118.9

111.6

R2=

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

B3LYP/6-31G(d)

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

HF/6-31G(d)

121.1 120.5 121.2 119.6 110.7 111.5 111.3 119.2 120.8 107.7 107.3 108.2 122.3 106.4 104.4 112.8 130.8 111.5 118.7 114.1 127.2 118.1 119.5 119.5 110.8 111.1 113.3 113.9 109.9 107.1 114.1 109.7 107.5 109.8 108.4 117.0 108.3 106.7 107.4 110.0 108.5 116.4 106.6 108.8 106.8 108.4 109.3 113.2 110.6 107.6 106.7 109.6 108.5 115.9 108.1 109.1 106.5 110.8 108.5 109.5 107.9 105.8 106.0 0.7860

120.9 120.7 121.2 119.5 110.9 111.5 111.4 119.3 120.9 107.4 107.2 108.2 122.2 106.5 104.4 113.1 130.6 111.6 118.8 113.9 127.2 117.5 118.6 119.2 110.8 110.8 113.2 113.9 110.3 107.0 114.0 109.9 107.3 109.8 108.3 117.0 108.2 106.7 107.4 110.0 108.6 116.3 106.6 108.8 106.8 108.4 109.3 113.1 110.6 107.6 106.7 109.7 108.5 115.8 108.1 109.0 106.5 110.8 108.6 109.5 107.9 105.9 106.0 0.7858

121.3 120.1 121.0 119.7 110.7 111.3 110.7 119.3 120.4 108.2 107.7 108.2 121.4 107.4 104.1 113.3 131.0 112.0 118.4 114.7 126.9 117.9 119.0 118.7 111.0 111.1 113.8 114.1 110.0 107.3 114.1 109.8 107.8 109.9 107.9 117.1 108.3 106.7 107.3 109.9 108.2 116.5 106.7 108.8 106.8 108.4 109.1 113.2 110.7 107.4 106.8 109.6 108.3 115.7 107.9 109.1 106.5 110.8 108.4 109.4 108.1 106.0 106.2 0.7833

121.3 120.1 121.0 119.6 110.9 111.4 110.8 119.3 120.4 108.1 107.6 108.0 121.5 107.5 103.9 113.6 131.4 112.6 118.5 114.6 126.9 117.8 118.5 118.4 111.3 111.2 113.9 113.8 110.3 107.3 113.9 109.9 107.7 110.0 107.9 116.9 108.2 106.9 107.3 110.0 108.4 116.3 106.9 108.8 106.8 108.4 109.1 113.1 110.7 107.5 106.8 109.6 108.3 115.6 108.0 109.0 106.5 110.8 108.5 109.4 108.2 106.0 106.2 0.7763

exclusively stretching modes as recognized in the PED% analysis column. All bands have been formed in the expected region, both theoretically and experimentally. CAH in-plane bending vibrations have been observed at 1470, 1371, 1286, 1279, 1156 and 1095 cm 1 in FT-IR and 1449, 1384, 1296, 1163 and 1098 cm 1 in Raman spectra for tolazamide

sample. CAH in-plane bending vibrations have been assigned to bands in observed region 1000–1300 cm 1 [27]. The higher correlations between scaled frequencies and experimental ones have been calculated in B3LYP hybrid functional approach. In analogy, CAH out-of-plane bending modes have been assigned to bands in observed region 900–675 cm 1 [26]. We have emphasized these

M. Karakaya et al. / Journal of Molecular Structure 1095 (2015) 87–95

91

generally assigned to 1601, 1504, 1384 and 1296 cm 1 frequencies in Raman spectra as not very strong. These modes have been computed as 1572, 1550, 1374, 1283 and 1279 cm 1 by B3LYP/6311++G(d,p) method and for example, the vibration corresponding to t23 mode is pure and computed as 56% contribution in PED analysis. Single Infrared band at 996 cm 1 and Raman band at 994 cm 1 have been assigned to CACAC in-plane bending vibrations of tolazamide with strong and medium intensity and activity. t80, t87, t91 and t103 modes have been calculated 779, 622, 514 and 319 cm 1 in B3LYP/6-311G++(d,p) level, respectively. CACAC outof-plane bending vibrations have been assigned to 951, 932, 677 and143 cm 1 in FT-IR and 958, 673 and 115 cm 1 in Raman spectra. These vibrations corresponds to values of 953, 935, 687, 399 and 100 cm 1 in B3LYP/6-311G++(d,p) level, theoretically. CH3 (methyl) vibrations

Fig. 2. Experimental FT-IR spectra and results obtained by using computational method for tolazamide.

CH stretching vibrations in methyl groups have been formed at lower frequencies in comparison with aromatic CH ones. These results are also reported for compounds containing different methyl aromatic ring [30]. The frequency of symmetric CH stretching mode on methyl is lower than asymmetric modes for the title compounds. Symmetric and antisymmetric CH stretching vibrations for methyl on aromatic rings have been reported at 2870 cm 1 and 2980 cm 1, respectively [31,32]. For tolazamide, the peaks at 2980 and 2960 cm 1 in FT-IR and 2947 cm 1 in Raman spectra have been assigned to CH3 asymmetric stretching vibration. CH3 symmetric stretching have been assigned at 2917 cm 1 in FT-IR, but symmetric stretching are not seen in Raman spectra. Symmetric and antisymmetric methyl deformations has been attributed to regions of 1390–1370 cm 1 and 1465–1440 cm 1, respectively, in methyl substituted aromatic structures [33–35]. The band at 1448 and 1438 and 1432 cm 1 in FT-IR and the bands at 1449 cm 1 in Raman are attributed to CH3 scissoring vibrations. In this study, the CH3 out-of-plane bending (torsion) vibrations cannot be observed in FT-IR and Raman spectra. This band have been calculated 45 cm 1. Also for C4AC7, tCC band have been observed 1179 and 654 cm 1 in FT-IR and 1191 and 635 cm 1 in Raman spectrum. SO2, NH, CS, SN (sulfonyl amide) group vibrations

Fig. 3. Experimental Laser-Raman spectra and results obtained by using computational method for tolazamide.

modes at 964, 951 and 799 cm 1 in FT-IR and 958, 800 cm 1 in Raman spectra. It can be argued that the CAH out-of-plane bending modes are within the characteristic region for the title compound.

Benzene ring vibrations C@C and CAC stretching vibrations have been attributed to the region of 1625–1400 cm 1 and 1380–1280 cm 1 [26,28] and ring stretchings to region 1620–1390 cm 1 [29] in aromatic ring for the most part. CAC bands, very strong and medium intensities, have been determined at 1560, 1553, 1371, 1286 and 1279 cm 1 in FT-IR spectra for tolazamide sample. CAC modes have been

Symmetric SAO stretching vibrations have been assigned to 1079, 1031 cm 1 (in FT-IR spectra) and 1098, 1033 cm 1 (in Raman spectra) in this work. Antisymmetric SAO stretching vibrations have been also assigned to frequency of 1232 cm 1 in FT-IR spectra and computed in 1258 cm 1 by B3LYP/6-311G++(d,p) basis set with high intensity and moderate PED (62%) contribution. SAO1,2 antisymmetric stretching modes have been recorded at 1341 and 1351 cm 1 (IR) and symmetric at 1150 cm 1 (IR) for N3-pyridinylmethanesulfonamide by Dodoff [36]. OASAO bending vibrations of OASAO have been assigned to 546 cm 1 in FT-IR and 543 cm 1 in Raman spectra and computed in 557 cm 1 by B3LYP/6-311G++(d,p) basis set with moderate intensity and low PED contribution. NAH vibrations normally focus on region of 3450–3250 cm 1 in previous studies [37]. NAH stretching mode in sulfonyl amide corresponds to 3443 cm 1 in B3LYP/6311G++(d,p) level with 100% PED contribution and experimentally 3377 cm 1 in FT-IR spectra for tolazamide. S–C stretching vibrations have been recorded in the region 780–510 cm 1 for aliphatic and aromatic sulfides [38,39]. In this study, this band has been seen in 654 cm 1 in FT-IR and 635 cm 1 in Raman spectrum. This band has been emphasized by Parimala and Balachandran [40] as a weak Raman band observed at 700 cm 1 (PED 70%). S–C stretching has been calculated 633 cm 1 by B3LYP/6-311G++(d,p) method in the present work.

Vib. No.

tNH(100) in the sulfonyl amide tNH(100) in the urea tCH(97) in the benzene tCH(100) in the benzene tCH(95) in the benzene tCH(91) in the benzene tCH(96) in the methyl assym. tCH(89) in the azepine tCH(90) in the azepine tCH(100) in the methyl assym. tCH(87) in the azepine tCH(73) in the azepine tCH(75) in the azepine tCH(76) in the azepine tCH(91) in the methyl symm. tCH837) in the azepine tCH(75) in the azepine tCH(68) in the azepine tCH(81) in the azepine tCH(80) in the azepine tCH(97) in the azepine tOC(77) in urea + tNC(10) in urea tCC(56) in the benzene tCC(60) benzene + dCCC(21) benzene dHNC(72) urea + tNC(11) urea dHCC(66) benzene + tCC(10) benzene dHCH(76) in the azepine dHCH(63) in the azepine dHCH(60) in the methyl dHCH(80) in the azepine dHCH(83) in the azepine dHCH(77)methyl + sHCCC(19) methy dHCH(80) in the azepine dHCH(64) in the azepine tCC(40)benzene + dHCC(10) benzene sHCNC(28) in the azepine dHCH(84) in the methyl sHCNC(28)azepine + dHCH(16)azepine dHCC(21)azepine + sHCNC(16)azepine dHNC(66) in the sulf. amide sHCNC(37) in the azepine sHCNC(19)azepine + dHCC(11)azepine sHCNC(50)azepine + dHCC(10)azepine dHCC(47)azepine tCC(38) benzene + dHCC(27) benzene tCC(39) benzene + dHCC(28) benzene dHCC(51)azepine + sHCNC(12)azepine tSO(62) assym. dHCC(30)azepine + sHCNC(17)azepine dHCC(43)azepine + sHCNC(11)azepine dHCC(21)azepine + sHCNC(14)azepine tNC(33)urea + tSO(14)asy + dHNC(12)urea tCC(48)benzene-methyl sHCNC(15)azepine dHCC(71) benzene + tCC(20)benzene tNC(43)azepine + tCC(11)azepine tNN(16)urea-aze + sHCNC(14)azepine dHCC(58)benzene + tCC(32)benzene sCCNC(30)az + dCCC(12)az + dCCN(10)az tSO(37)sym + tCC(24)ben + tSC(12) tCC(23)azep + tNN(19)urea-azepine tCC(37)azep

Observed frequencies

Calculated frequencies in cm

IR

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

3377 3316 3108 3108 3049 3049 2980 2960 2960 2960 2947 2941 2929 2929 2917 2910 2903 2861 2861

Raman

3077 3055 3055

2947 2947 2947 2929

2866

1706 1560 1553

1775 1601 1504

1470 1450 1442 1438 1438 1432 1432 1426 1420 1371 1360 1360 1353 1347 1341 1336 1336 1316 1296 1286 1279

1449 1449 1449 1449 1449 1449 1449 1449 1449 1384 1353 1353 1353 1353 1334 1334 1334 1321 1296 1296 1296

1232 1232 1232 1204 1188 1179 1165 1156 1127 1107 1095 1087 1079 1072 1031

1210 1210 1210 1210 1191 1191 1163 1163 1124 1124 1098 1098 1098 1098 1033

1

(IR intensities/Raman activity) B3LYP/6-31G(d)

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

HF/6-31G(d)

Freq.

IR int.

Ra.act.

Freq.

IR int.

Ra.act.

Freq.

IR int.

Ra.act.

Freq.

IR int.

Ra.act.

3443 3326 3086 3076 3048 3046 2990 2971 2968 2962 2948 2939 2933 2929 2911 2908 2901 2896 2889 2828 2797 1726 1572 1550 1519 1464 1450 1443 1436 1436 1433 1431 1426 1421 1374 1365 1361 1350 1344 1340 1336 1329 1315 1296 1283 1279 1264 1258 1250 1220 1204 1186 1181 1165 1160 1126 1106 1095 1084 1078 1070 1032

67.5096 36.4597 1.0694 1.4378 7.9193 9.4803 12.7233 24.9143 21.7755 12.0550 66.1119 20.0196 57.8561 45.2886 19.8945 29.5859 14.5147 28.6166 29.4676 50.9382 58.7434 384.5000 24.0769 1.0599 183.7885 8.8811 2.9741 12.6803 16.3388 5.2635 5.9864 7.9464 1.4450 1.7550 11.2213 3.1058 2.0550 2.5468 7.4062 87.9158 0.0787 2.3882 0.4350 2.3993 7.3284 2.5212 4.4124 325.0615 5.1439 2.8781 1.4272 90.7581 26.8119 21.0447 8.2741 12.3612 48.3704 10.0526 0.3482 145.0280 56.6532 9.6911

65.3324 140.9153 72.3046 84.4634 84.6884 104.0017 58.7529 136.9025 48.5664 97.4725 58.1806 74.1477 199.4904 84.9898 334.6686 122.6816 154.2030 45.6041 111.9639 78.7650 84.7289 18.2331 71.1121 5.1949 9.0420 1.2711 4.1673 3.9235 12.1892 8.7675 2.2305 10.8365 8.3927 9.7576 0.6509 0.7404 24.9959 1.5052 3.6241 2.3019 0.2948 1.6353 0.1256 8.5379 1.3906 0.5009 6.3707 9.0876 2.1464 3.0565 2.1407 4.0885 22.5418 0.1379 2.9841 0.9057 2.1754 0.3481 3.6947 58.5889 7.4423 2.8907

3444 3325 3111 3102 3069 3068 3012 2992 2989 2986 2971 2962 2954 2950 2929 2927 2921 2915 2909 2845 2815 1769 1592 1567 1528 1482 1477 1470 1462 1461 1460 1459 1452 1447 1391 1387 1387 1369 1364 1354 1350 1344 1330 1310 1302 1291 1279 1276 1262 1233 1218 1200 1191 1177 1172 1140 1117 1106 1096 1093 1081 1044

63.3088 31.4092 1.2550 1.5126 9.5409 13.7510 12.5456 28.1382 24.9804 15.4105 68.9730 18.0204 41.9100 58.4497 21.2229 31.6165 17.5843 25.0930 27.6756 48.6147 53.6424 302.5456 21.1131 1.1326 199.3228 6.9379 1.7822 9.4597 0.8238 13.0758 3.4031 7.4146 0.2309 1.5767 14.0601 0.7337 3.9211 8.7291 5.2998 0.8860 4.1494 129.4414 0.2936 2.8544 1.9718 0.6700 243.2114 7.2362 2.8686 3.0391 0.8016 133.2533 17.8599 19.0130 7.0231 12.7509 46.9942 9.2447 0.8693 163.2133 39.9666 83.6458

65.7205 122.8644 73.1227 79.6974 85.4941 95.4094 59.8973 111.9511 58.5986 99.1976 57.2820 69.5658 87.3768 126.6530 254.2086 114.6767 122.4904 33.4227 69.2207 53.9647 51.5805 10.8846 78.5681 5.4531 10.5513 1.0694 5.4599 6.8134 16.5875 20.4230 2.9418 20.6397 17.7673 18.8207 1.1285 40.5860 9.5831 2.1282 6.0757 3.0269 4.4260 2.1186 0.1650 18.9268 1.3071 0.3547 5.5870 16.3388 3.8272 5.3518 5.0000 2.5876 13.6257 0.7613 4.1137 1.4372 3.7840 0.7038 2.5850 52.5087 3.0001 4.6609

3458 3416 3057 3043 3018 3012 2944 2938 2929 2920 2907 2896 2888 2883 2871 2866 2859 2850 2845 2815 2783 1774 1618 1586 1579 1500 1483 1472 1467 1462 1458 1454 1452 1448 1415 1411 1396 1392 1387 1384 1373 1371 1341 1329 1318 1306 1287 1277 1253 1241 1232 1194 1190 1178 1175 1174 1146 1129 1109 1089 1077 1066

98.8510 53.8733 0.9691 1.2745 9.9286 9.9392 19.9319 36.6407 35.3163 17.6186 101.2219 24.5821 89.6662 53.2815 26.9319 47.8803 25.5614 30.2853 37.5073 43.1848 46.5628 535.1612 46.6610 10.3421 199.8724 8.5031 2.1009 8.3867 3.8680 4.6243 21.5660 2.0180 7.2366 0.7436 13.2626 135.3959 3.5755 1.4581 9.2246 2.9498 0.3858 3.1723 0.2988 2.1299 352.5248 38.1048 6.6871 1.5433 88.4138 66.1263 20.1189 7.3511 13.3580 9.1368 17.8174 8.6445 68.0903 286.4349 1.3844 10.3084 70.5486 39.7280

44.9341 51.6579 64.3220 78.5023 69.3496 83.1827 54.8054 124.9057 57.6503 85.6651 42.0947 63.1488 240.2722 43.0979 226.1643 143.2408 158.8642 40.7449 76.4837 51.2637 52.0155 7.5924 53.8554 4.8281 2.6214 0.6511 3.0971 1.0353 3.6020 6.8685 7.1641 7.3397 8.7449 10.3370 2.2749 1.5280 2.9834 5.2896 1.5244 0.9292 0.2772 0.7253 0.0433 6.1950 4.4029 1.3517 4.2608 5.4709 3.9424 0.8398 5.2149 8.4825 0.5706 0.6450 1.9947 0.5207 7.6852 29.8735 2.0984 2.7957 3.8580 4.3822

3424 3384 3054 3040 3013 3007 2940 2936 2928 2916 2906 2896 2887 2883 2866 2865 2858 2849 2845 2815 2785 1787 1614 1580 1565 1498 1487 1477 1472 1466 1462 1458 1456 1453 1413 1402 1399 1392 1385 1381 1372 1369 1341 1325 1315 1303 1282 1272 1249 1238 1228 1190 1186 1176 1171 1169 1139 1127 1106 1082 1077 1066

109.4119 54.6013 1.3220 1.7798 12.3772 12.6485 20.1654 37.4938 35.9047 21.4562 94.0243 21.2622 64.7693 68.2507 28.5502 46.3295 35.0187 29.1121 33.9916 42.9641 43.8667 471.6391 43.3334 7.8112 214.8905 7.3338 1.3360 5.5955 1.7111 2.8781 16.9207 1.3552 5.7052 1.0271 5.1672 84.3009 78.8840 14.6174 13.5163 4.3164 1.8983 4.0745 0.3275 3.8951 317.3623 25.0695 5.7782 2.3930 107.9816 71.0337 15.4778 8.4526 13.3870 7.2828 9.5469 16.5142 65.8497 281.7921 1.4692 6.4342 41.8849 73.8814

46.0528 46.2314 65.4622 79.1689 71.7702 86.2721 59.8660 111.8693 57.4068 102.7222 45.2652 60.0965 134.9921 89.4459 177.2598 132.6452 129.5503 38.3452 55.4515 42.0340 38.1002 4.7748 56.8088 4.4017 3.3491 0.5119 4.5905 2.4134 5.3575 15.0741 14.3968 14.5681 19.0283 18.7228 4.4753 7.7612 8.7741 2.1731 2.2149 2.1519 0.9147 2.2096 0.1002 13.1208 3.1130 1.2089 10.5278 9.4254 3.4072 2.6015 8.2000 4.9359 1.4323 1.3058 0.8538 2.9786 9.6697 24.0769 1.6506 2.7277 1.2613 4.1772

M. Karakaya et al. / Journal of Molecular Structure 1095 (2015) 87–95

m1 m2 m3 m4 m5 m6 m7 m8 m9 m10 m11 m12 m13 m14 m15 m16 m17 m18 m19 m20 m21 m22 m23 m24 m25 m26 m27 m28 m29 m30 m31 m32 m33 m34 m35 m36 m37 m38 m39 m40 m41 m42 m43 m44 m45 m46 m47 m48 m49 m50 m51 m52 m53 m54 m55 m56 m57 m58 m59 m60 m61 m62

Assignments and PED%a

92

Table 3 Observed frequencies in IR-Raman spectra and calculated vibrational frequencies for tolazamide structure.

Table 3 (continued) Vib. No.

115

m113 m114 m115 m116 m117 m118 m119 m120

tSO(41)sym + tCC(23)benzene sHCCC(45)+dHCH(15)methyl dCCC(58)benzene tCC(19)azepine + dHCC(18)azepine tNC(16)urea + tCC(11)azepine sHCCC(43)benzene + dHCH(15)methyl tNC(12)urea + dNNC(10)urea-azepine sHCCC(83)benzene + sCCCC(10)benzene sHCNC(23)azepine + tNC(17)azepine sHCCC(69)benzene + sCCCC(16)benzene sHCNC(14)azepine + tCC(12)azepine dHCC(10)azepine + sCCNC(10)azepine tCC(23)azep tSN(17)sulfanilamide sHCCC(93)in the benzene tNC(17)azep + tSN(15)sulfanilamide sHCCC(84)in the benzene tCC(35)benzene-meth + dCCC(15)benzene tCC(31)azepine + cONNC(16)urea cONNC(56)urea sHCNC(19)urea + cONNC(15)urea sCCCC(55)benzene + cCCCC(13)benzene dOCN(14)urea cONOS(26)s.a + tCC(12)met-bnz + tSC(21) dCCC(80)benzene sHNCN(71)urea dOSO(21) tNC(12)+dCCN(12)+sCCNC(10) hepsi azep cONOS(28)sulfamide + dCCC(11)benzene sHNCN(70) urea dCCC(13)azepine + dCCN(12)azepine sCCCC(44)benzene + dOSO(13)+cSCCO(12) dCNN(34)urea-azep + dCNC(16)azep. sCCNN(21)azepine + sCCNC(12)azepn cONCS(29)+dSCC(20)+dCCC(15)ben-met sCCCC(70) benzene tSN(16)s.amide + dNCN(16)urea + dCCC(10)azep dCCN(17)azep + dCCC(15)azep dCCN(19)azep dNSC(21)+dOSO(18)+cCCCC(12) dCCC(24)benzene dCCC(20)ben-methy + cONCS(15) tSC(48) + dCCC(14)benzene + cONOS(13) dNNC(21)aze-ur + dOCN(11)urea + dCNC(11)aze dOSN(35)sulfami + cONOS(10) + dCNS(10) dNSC(28) + sCCCC(12) + cCCCC(12) + cSCCC(11) sCCNC(52)azepine cONCS(23) + dSCC(57) dCNS(13) sCCCC(20)benzene + cSCCC(15) + sNNCN(12) + sNCNS(11) + sCNSC(10) 100 sCCNC(11) sNCNS(42) + sCNNC(12) sNNCN(35) + cSCCC(16) + dNSC(12) sHCCC(69) sCCNC(23) + cCCNN(23) + dCNN(12) sNSCC(67) sNSSC(53) sCNNC(67)

Observed frequencies

Calculated frequencies in cm

IR

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

Raman

1031 1019 996 988

1033 1033 994 994

964 951 951 940 932 883

958 958 958 958 958 888

842 820

866 817

813 799

817 800

750 731 725 677 654 654

751 751 751 673 653 635

546 546

600 543 543

500 487 467 436 423 406

500 500 469 445 414 414 365 352 326

255 252 248 222 184 164 158 143 3.5549

287 242 242 215

115 0.1931

69

R2=

1

(IR intensities/Raman activity) B3LYP/6-31G(d)

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

HF/6-31G(d)

Freq.

IR int.

Ra.act.

Freq.

IR int.

Ra.act.

Freq.

IR int.

Ra.act.

Freq.

IR int.

Ra.act.

1031 1020 992 990 979 970 954 953 941 935 890 858 841 822 817 811 796 779 740 733 722 687 648 633 622 580 557 528 514 505 489 469 437 421 407 399 363 344 339 326 319 304 268 242 238 202 167 156 136

86.8079 10.0101 15.1834 2.9714 63.9100 1.2239 52.2010 1.2134 8.8184 0.3524 12.7251 1.3282 16.3047 76.8152 5.8117 85.5477 19.4315 5.5747 4.8649 3.8314 2.7209 3.6476 4.0256 192.9945 0.1742 62.0362 132.7308 30.1657 82.4844 43.5447 3.9561 2.6508 2.0543 3.5450 0.2199 0.0087 6.5894 0.0125 0.4267 2.0229 0.2694 2.3875 1.3597 2.3051 1.3376 3.7766 1.7589 1.7652 6.4050

5.5556 0.3384 1.4120 5.7373 2.9099 0.4435 1.9420 0.1441 1.5950 0.0454 0.5393 3.3954 7.6480 10.6814 1.0808 2.6728 1.4328 33.7873 8.9682 1.2239 1.1259 0.0804 1.2446 6.7351 6.0244 1.2585 5.3678 2.4125 2.3894 2.1810 0.9744 3.2130 1.4081 2.7555 1.3445 0.0432 3.6760 1.6105 2.5731 1.2940 0.3579 0.4764 8.6674 0.5094 1.5212 1.1210 0.1230 0.4105 0.5576

1039 1034 1000 994 988 983 961 950 939 934 898 867 848 831 822 818 798 783 745 732 721 684 649 637 623 592 560 529 517 506 492 471 439 423 409 400 364 345 340 328 321 305 271 243 238 201 167 158 138

0.6070 16.8519 5.8028 11.6139 43.8884 0.2003 47.4653 8.6405 0.1381 0.0233 12.1645 1.4677 23.0600 100.7384 0.5443 69.2671 15.6571 6.2755 3.7096 2.0183 9.1623 5.0976 6.5180 192.4895 1.4828 61.2322 129.8201 26.9311 74.9191 69.8905 5.3826 1.7665 2.7716 4.3881 0.2149 0.0568 6.8243 0.0772 0.4133 1.9929 0.3950 2.5996 1.8362 1.5854 2.0002 3.0094 1.4670 2.0880 6.0795

5.3494 0.2287 5.9393 1.6039 3.8555 1.9343 3.3705 2.6959 0.3485 1.1164 0.9879 2.3901 9.2774 12.6263 3.3995 1.7452 2.6318 25.2961 10.3390 0.7951 0.7599 0.1052 1.4607 6.9489 7.1019 1.5335 4.9570 2.3978 2.3134 3.0817 0.7998 3.1464 0.9212 1.4843 1.2677 0.0719 3.5313 1.6110 2.6835 1.5160 0.3869 0.4689 7.8361 0.7173 1.5762 1.3758 0.0899 0.4004 0.5976

1051 1038 1013 1005 1002 1000 985 978 976 962 915 886 869 853 842 835 827 787 777 743 732 702 670 666 627 592 583 543 536 520 496 491 446 429 421 408 383 356 346 343 323 311 281 249 244 214 166 164 138

3.8338 0.6228 101.9415 0.3603 3.4915 0.1679 18.8883 3.0261 0.4406 7.6648 60.0936 74.7370 2.6060 1.3386 16.3468 17.1743 30.5853 6.6934 29.2508 2.0142 1.9565 21.0266 3.3118 275.7671 0.2470 86.1639 140.1602 103.1518 5.6097 40.4569 10.8392 1.9972 2.6801 4.6585 0.6664 0.1673 8.6811 0.4775 2.8231 0.2275 0.4322 3.0434 1.8806 3.2694 1.6504 5.2102 2.3857 1.8559 4.6565

0.0596 5.6043 2.3731 6.5177 0.8413 0.0847 3.9335 0.5431 0.0112 1.5215 3.6528 5.6135 2.3277 0.5279 1.2481 2.2669 0.4678 37.1727 0.5383 12.6752 2.4241 0.5348 0.8943 4.1595 6.2179 1.4924 1.1043 0.4153 4.1178 1.3549 0.9229 0.6182 1.0209 2.4551 1.1997 0.0537 3.2408 0.5761 1.1682 0.7086 0.3803 0.2615 8.2584 1.1806 0.5273 1.3167 0.0616 0.3205 0.4278

1049 1030 1006 999 996 992 978 977 977 958 909 880 864 851 836 829 824 783 761 739 728 700 662 659 621 591 582 537 531 509 492 487 442 426 418 405 376 352 343 339 319 306 279 247 242 211 163 163 135

4.3521 0.3693 85.3614 5.2807 3.8722 0.0565 10.3675 2.2122 10.3730 6.7131 61.9367 98.2699 3.8195 1.0492 16.0407 18.0936 25.5733 5.4332 48.0324 1.7389 2.2450 28.2456 22.0161 253.8803 0.4482 48.6555 188.4349 98.5372 5.2145 55.3582 16.4096 1.4019 3.2008 5.1006 0.9038 0.3201 9.6026 0.4225 2.8709 0.1703 0.5527 3.3742 2.4095 3.4896 1.8796 4.2633 2.1884 1.8834 4.5521

0.0999 6.7317 2.0754 8.3823 1.1092 0.0825 2.8901 2.1891 2.2629 2.0758 4.2401 6.1170 2.4100 1.9293 1.5082 2.4638 2.2727 28.4011 0.6167 12.5149 2.8693 0.1367 1.7155 3.2885 6.8564 1.0829 1.5876 0.3870 3.9945 2.3388 1.0072 0.5507 0.7905 1.7992 1.2139 0.0842 3.6604 0.4518 1.5141 0.6785 0.4414 0.3174 7.3366 1.5145 0.5878 1.6820 0.0632 0.3440 0.3853

101 94 61 52 45 41 34 16 13 0.9998

3.1549 1.2745 0.5300 0.7388 0.2494 0.2127 0.0980 0.7068 0.5647

0.1761 0.4684 0.8608 2.6129 1.4712 0.5274 4.5009 2.3519 0.2204

106 95 60 52 45 40 31 17 13 0.9998

5.0686 1.3435 0.3723 0.5675 0.2721 0.1249 0.1915 0.5713 0.5097

0.2423 0.3994 0.7900 3.6837 1.3921 0.3419 6.6645 0.9550 2.9049

106 99 59 53 42 33 27 19 14 0.9990

4.7548 1.3753 0.4853 0.8598 0.1765 0.0962 0.1028 0.8652 0.8475

0.2847 0.3706 0.6639 2.0357 0.2093 3.9176 0.3918 0.1769 1.7722

98 60 53 40 33 21 20 13 0.9991

1.3223 0.3852 0.6480 0.1348 0.1115 0.0299 0.8777 0.7342

0.4153 0.6820 2.7429 0.5372 6.3580 0.0838 0.3484 2.3644

M. Karakaya et al. / Journal of Molecular Structure 1095 (2015) 87–95

m63 m64 m65 m66 m67 m68 m69 m70 m71 m72 m73 m74 m75 m76 m77 m78 m79 m80 m81 m82 m83 m84 m85 m86 m87 m88 m89 m90 m91 m92 m93 m94 m95 m96 m97 m98 m99 m100 m101 m102 m103 m104 mm105 m106 m107 m108 m109 m110 m111 m112

Assignments and PED%a

t, stretching; d, in-plane bending; c, out-of-plane bending; s, torsion. a

Potential energy distribution (PED), less than 10% are not shown. 93

94

M. Karakaya et al. / Journal of Molecular Structure 1095 (2015) 87–95

Also, S–C out of plane vibration has been assigned to 222 cm 1 (FTIR) and 215 cm 1 (Raman spectra). S–N stretching vibration has been observed at 820 and 813 cm 1 in FT-IR (medium band) and 817 cm 1 in Raman spectra and contributions of S–N modes are 17% and 15% in PED analysis. These modes have been calculated at 822 and 811 cm 1 in B3LYP/6-311G++(d,p) method.

C@O, NH and NC (urea) group vibrations C@O stretching modes are stronger absorption bands within the range of 1850–1550 cm 1 in general [41]. Strong absorption or high intensity in these modes can be caused by formation of hydrogen bonds for carbonyl groups [42]. Strong bands observed at 1775 cm 1 (Raman spectra) and 1706 cm 1 (IR spectra) have also been assigned as C@O stretching vibration in present work. Theoretical wavenumbers for C@O mode are 1726 and 1774 cm 1, 77% PED, in B3LYP and HF approaches, respectively, 6-311G++(d,p) level. It is noteworthy that the deviations in frequency are very high according to experimental results. These results can be attributed strong intramolecular hydrogen bonding on NAH structure. Free NAH stretching vibrations are ordinarily observed in the region of 3460–3300 cm 1 [25]. This mode has been computed 3326 cm 1 (B3LYP) and 3416 cm 1 (HF), 6-311G++(d,p) basis set with the full PED% contribution and formed as stretching between N2AH9 in urea group. This mode has been observed at 3316 cm 1 in FT-IR spectra. Intramolecular NAH


O interaction may affect the vibration modes, especially, in sulfonyl amide and urea groups. The mode of tN2AC8 has been observed 1188 cm 1 in FT-IR, 1191 cm 1 in Raman spectrum and computed 1519 and 1186 cm 1 in B3LYP/6-311G++(d,p) level. Additionally, t[urea-azepine] have been calculated 1106 cm 1 in B3LYP/6-311G++(d,p) method and assigned to 1107 cm 1 in FT-IR and 1124 cm 1 in Raman spectrum. dHNC, in plane bending, vibration in the urea have been assigned to 1188 cm 1 (FT-IR), 1191 cm 1 (Raman) and calculated 1519 cm 1 (mode No. 25) and 1186 cm 1 (mode No. 52) by B3LYP/6-311G++(d,p) level with very low PED% contribution. It is difficult to determine the vibration modes in the low frequency region because of weak intensity and low PED% values.

The azepine ring vibrations Symmetric and antisymmetric methylene stretching modes have been correspond to region 2900–2800 cm 1 and 3000– 2900 cm 1, respectively [43,44]. In this work, it is clear that the CAH stretch-modes in azepine ring have been defined at lower frequencies than aromatic CAH ones. For tolazamide, CH2 antisymmetric and symmetric stretching vibrations have been assigned to 2960, 2947, 2941, 2929 cm 1 and 2910, 2903, 2861 cm 1 (FTIR) and 2947, 2929 cm 1 and 2866 cm 1 (Raman), respectively. Also, computed methylene stretching vibrations in azepine moiety are at 2971, 2968, 2948, 2939, 2933, 2929, 2908, 2901, 2896, 2889, 2828 and 2797 cm 1, respectively, with B3LYP approach and 6311G++(d,p) basis set. The modes defined the CAC and CAN stretching have been clustered at low frequencies. For example, CAN stretching in azepine group have been observed in range of 1127–940 cm 1 (FT-IR) and 1124–958 cm 1 (Raman) for this work. The CH2 scissoring modes have been calculated at 1421 and 1450 cm 1 in B3LYP/6-311G++(d,p) with high PED%. This mode is located in 1420 and 1450 cm 1 in FT-IR and about 1449 cm 1 in Raman spectra. Also, the methylene scissoring modes have been calculated at about 1445 and 1454 cm 1 in IR bands by Karabacak et al. [45]. CH2 wagging modes as symbolized by the sHCNC have been observed at 1360, 1353, 1347, 1336, 1316, 1232 and 1204 cm 1 in FT-IR spectra and 1353, 1334, 1321 and 1210 cm 1 in Raman spectra. Similarly, CH2 twist modes (t44, t49, t50, t51, t54) have been observed at 1296, 1232, 1204, 1165 cm 1 (FT-IR spectra) and 1296, 1210, 1163 cm 1 (Raman spectra) inazepine ring. qCH2 mode has been also assigned to single band at 988 cm 1 and 994 cm 1 for IR and Raman spectra, respectively. This mode has been resulted as t74 in simulation program but has not been assigned to a frequency in FT-IR and Raman spectrum region. CH2 bending modes have been ordered as CH2 (scis), CH2 (wagg), CH2 (twist), CH2 (rock) during the high frequencies to low ones. Frontier molecular orbital energies HOMO and LUMO energies of tolazamide have been given in Table 1. The most stable result is at B3LYP method,

Fig. 4. Frontier molecular orbital plots of tolazamide.

M. Karakaya et al. / Journal of Molecular Structure 1095 (2015) 87–95

6-311G++(d,p) set with 1334.47 hartree/part. electronic–zero point energy. HOMO and LUMO energies as frontier molecular orbitals are important to define the optical and electrical properties of compounds in quantum chemistry calculations [46–48]. HOMO and LUMO act as electron donor and acceptor, respectively. In addition to tend of electron donor and acceptor, it can be highlighted that HOMO energy is used for the definition of ionization potential and LUMO energy is also for the electron affinity. Ionization potential and electron affinity can be expressed by I = –EHOMO and A = –ELUMO, respectively [47,49]. HOMO–LUMO high energy gap is defined as a hard compound, that is, small energy gap between HOMO and LUMO means that this compound is more reactive [50]. Also, the large first and third-order hyperpolarizabilities are obtained at lower HOMO–LUMO energy gaps [51]. In our previous study [14] HOMO and LUMO energies, and the gap energy value of HOMO–LUMO for gliclazide have been calculated at HF and B3LYP/6-311++G (d,p) level of theory. As a result, at HF/6311++G(d,p) level, HOMO–LUMO gap value is more higher, 102.98 kcal/mol, than at B3LYP/6-311++G(d,p) level [14]. The HOMO is located on sulfonylurea group, intensively over pyrrole moiety, the LUMO is more focused on benzene group but there is less concentration on sulfonylurea moiety [14]. HOMO, LUMO energies and energy gap for tolazamide have been computed at HF and B3LYP approach, 6-31G(d) and 6-311G++(d,p) level. Minimal value for HOMO–LUMO energy gap is 0.18287 a.u. at B3LYP/6-311G++(d,p) basis set as shown in Table 1. In addition, HOMO and LUMO plots resulted by B3LYP/6311G++(d,p) level are given in Fig. 4. HOMO has been focused on azepine ring (intensely) and urea, partially over the sulfonyl amide. Also, LUMO is more focused on benzene ring, sulfonyl amide (intensely) and over the urea group (partially). Conclusions This paper has been presented the investigations on optimized geometry and theoretical vibrational analysis of tolazamide combined with FT-Infrared and Laser-Raman spectroscopic data. Ab initio calculations have been performed by the agency of HF and B3LYP approaches, 6-31G(d) and 6-311G++(d,p) level. Electronic and zero point energies have lower values at B3LYP/6311G++(d,p) basis set. In general, the calculation results optimized parameters and scaled harmonic vibrational frequencies are consistent with comparing experimental data. Considerable level of correlation has been noticed. The detailed PED% analysis of the compound showed a good agreement with the experimental data. The modes corresponding to the vibrational frequencies have been interpreted by PED analysis. The calculated HOMO and LUMO along with their plot has been presented for understanding of charge transfer occurring within the molecule. The images of HOMO–LUMO and energies of tolazamide have been also reviewed. These results are taken into account; we conclude that the compound is an attractive object for future theoretical and experimental pharmacological studies. The theoretical results on scaled harmonic vibrational frequencies, structure parameters, electronic-zero point energies and molecular orbital have showed that the structure obtained by B3LYP approach is more stable. References [1] [2] [3] [4]

C.H. Koo, J.S. Suh, Y.H. Yeon, T. Watanabe, Arch. Pharm. Res. 11 (1988) 74–79. K.A.A. Nirmala, D.S.S. Gowda, Acta Cryst. B37 (1981) 1597–1599. W. Czernicki, M. Baranska, Vib. Spectrosc. 65 (2013) 12–23. G. Mariappan, B.P. Saha, S. Datta, D. Kumar, P.K. Haldar, J. Chem. Sci. 123 (2011) 335–341. [5] N. Nikolac, A.M. Simundic, D. Katalinic, E. Topic, A. Cipak, V.Z. Rotkvic, Arc. Med. Res. 40 (2009) 387–392.

95

[6] H. Zhang, Y. Zhang, G. Wu, J. Zhou, W. Huang, X. Hu, Bioorg. Med. Chem. 19 (2009) 1740–1744. [7] C. Leon, J. Rodrigues, N.G. Dominguez, J. Charris, J. Gut, P.J. Rosenthal, J.N. Dominguez, Eur. J. Med. Chem. 42 (2007) 735–742. [8] X. Liu, P. Xi, F. Chen, Z. Xu, Z. Zeng, J. Photochem. Photobiol. B 92 (2008) 98– 102. [9] T. Rajamani, S. Muthu, M. Karabacak, Spectrochim. Acta A 108 (2013) 186–196. [10] T.H. Maren, Ann. Rev. Pharmacol. Toxicol. 16 (1976) 309–327. [11] H.J. Bestmann, F. Kern, D. Witschel, M.C. Angew, Chem. Int. Ed. Engl. 31 (1992) 795–796. [12] E.L.R. Stokstad, T.H. Jaoekes, J. Nutr. 117 (1987) 1335–1341. [13] A. Saeed, A. Mumtaz, U. Flörke, Eur. J. Chem. 1 (2010) 73–75. [14] M. Karakaya, M. Kürekçi, B. Eskiyurt, Y. Sert, Ç. Çırak, Spectrochim. Acta A135 (2015) 137–146. [15] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R. Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G.A. Petersson, H. Nakatsuji, M. Caricato, X. Li, H.P. Hratchian, A.F. Izmaylov, J. Bloino, G. Zheng, J.L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven, J.A. Montgomery, Jr., J.E. Peralta, F. Ogliaro, M. Bearpark, J.J. Heyd, E. Brothers, K.N. Kudin, V.N. Staroverov, R. Kobayashi, J. Normand, K. Raghavachari, A. Rendell, J.C. Burant, S.S. Iyengar, J. Tomasi, M. Cossi, N. Rega, J.M. Millam, M. Klene, J.E. Knox, J.B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R.E. Stratmann, O. Yazyev, A.J. Austin, R. Cammi, C. Pomelli, J.W. Ochterski, R.L. Martin, K. Morokuma, V.G. Zakrzewski, G.A. Voth, P. Salvador, J.J. Dannenberg, S. Dapprich, A.D. Daniels, Ö. Farkas, J.B. Foresman, J.V. Ortiz, J. Cioslowski, D.J. Fox, Gaussian 09, revision A.1. Gaussian Inc, Wallingford CT, 2009. [16] D.C. Young, Computational Chemistry A Practical Guide for Applying Techniques to Real-World Problems (Electronics), John Wiley and Sons, New York, 2001. [17] M.H. Jamróz, Vibrational Energy Distribution Analysis VEDA 4 Computer Program, Warsaw, 2004. [18] M.H. Jamróz, J.C. Dobrowolski, R. Brzozowski, J. Mol. Struct. 787 (2006) 172– 183. [19] Ç. Çırak, S. Demir, F. Ucun, O. Cubuk, Spectrochim. Acta A 79 (2011) 529–532. [20] H. Arslan, O. Algul, Spectrochim. Acta A. 70 (2008) 109–116. [21] Ç. Çırak, Y. Sert, F. Ucun, Spectrochim. Acta A 92 (2012) 406–414. [22] Y. Sert, Ç. Çırak, F. Ucun, Spectrochim. Acta A 107 (2013) 248–255. [23] D.N. Sathyanarayana, Vibrational Spectroscopy: Theory and Applications, New Age International Publishers, New Delhi, 2004. [24] G. Socrates, Infrared and Raman Characteristic Group Frequencies-Tables and Charts, third ed., Wiley, New York, 2001. [25] F.R. Dollish, W.G. Fateley, F.F. Bentley, Characteristic Raman Frequencies of Organic Compounds, Wiley, New York, 1997. [26] M. Govindarajana, M. Karabacak, Spectrochim. Acta A 94 (2012) 36–47. [27] A. Altun, K. Golcuk, M. Kumru, J. Mol. Struct. (Theochem) 625 (2003) 17. [28] V. Krishnakumar, R.J. Xavier, Appl. Phys. 41 (2003) 95–98. [29] V.S. Madhavan, H.T. Varghese, S. Mathew, J. Vinsova, C.Y. Panicker, Spectrochim. Acta A 72 (2009) 547–553. [30] M. Karabacak, Z. Cinar, M. Kurt, S. Sudha, N. Sundaraganesan, Spectrochim. Acta A 85 (2012) 179–189. [31] D. Sajan, I. Hubert, J. Raman Spectrosc. 37 (2005) 508–519. [32] M. Gussoni, C. Castiglioni, M.N. Ramos, M.C. Rui, G. Zerbi, J. Mol. Struct. 224 (1990) 445–470. [33] B.V. Reddy, G.R. Rao, Vib. Spectrosc. 6 (1994) 231–250. [34] J.F. Areanas, I.L. Tocn, J.C. Otero, J.I. Marcos, J. Mol. Struct. 410 (1997) 443–446. [35] D.A. Long, W.O. Jeorge, Spectrochim. Acta 19 (1963) 1777–1790. [36] N.I. Dodoff, Vib. Spectrosc. 4 (3) (2000) 5–9. [37] M. Silverstein, G.C. Bassler, C. Morril, Spectroscopic Identification of Organic Compounds, John Wiley, New York, 1981. [38] S. Gunasekaran, S. Ponnambalam, S. Muthu, L. Mariappan, Asian J. Phys. 16 (1) (2003) 51–63. [39] C.S. Hsu, J. Spectrosc. Lett. 7 (1974) 439–447. [40] K. Parimala, V. Balachandran, Spectrochim. Acta A 81 (2011) 711–723. [41] G. Socrates, Infrared Characteristic Group Frequencies, John Wiley & Sons, New York, 1981. [42] C. Meganathan, S. Sebastian, I. Sivanesan, K.W. Lee, B.R. Jeong, H. Oturak, S. Sudha, N. Sundaraganesan, Spectrochim. Acta Part A 95 (2012) 331–340. [43] D. Sajan, J. Binoy, B. Pradeep, K. Venkatakrishnan, V.B. Kartha, I.H. Joe, V.S. Jayakumar, Spectrochim. Acta A 60 (2004) 173–180. [44] S. Gunasekaran, S.R. Varadhan, K. Manoharan, Asian J. Phys. 2 (1993) 165–172. _ Erol, M. Kurt, J. Mol. Struct. 886 (2008) 148– [45] M. Karabacak, E. Sahin, M. Çınar, I. 157. [46] I. Fleming, Frontier Orbitals and Organic Chemical Reactions, Wiley, London, 1976. [47] M. Govindarajan, M. Karabacak, A. Suvitha, S. Periandy, Spectrochim. Acta A 89 (2012) 137–148. [48] M.M. El-Nahass, M.A. Kamel, E.F. El-deeb, A.A. Atta, S.Y. Huthaily, Spectrochim. Acta A 79 (2011) 443–450. [49] T. Vijayakumar, I. Hubert Joe, C.P.R. Nair, V.S. Jayakumar, Chem. Phys. 343 (2008) 83–99. [50] K. Chaitanya, Spectrochim. Acta A 86 (2012) 159–173. [51] A. Karakas, A. Migalska-Zalas, Y. El Kouari, A. Gozutok, M. Karakaya, S. Touhtouh, Opt. Mater. 36 (2014) 22–26.