Der Pharma Chemica
Journal for Medicinal Chemistry, Pharmaceutical Chemistry, Pharmaceutical Sciences and Computational Chemistry

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Research Article - Der Pharma Chemica ( 2018) Volume 10, Issue 8

The Investigation of Spectral and Theoretical Properties of 2-(3-Cyclopropyl-4,5-dihydro-1H-1,2,4-triazol-5-on-4-yl-iminomethyl) Benzoic Acid by Using B3LYP/HF 6-31g (d,p) Basis Set

Medetalibeyoğlu H*, Özdemir G and Yüksek H

Department of Chemistry, Kafkas University, 36100 Kars, Turkey

*Corresponding Author:
Medetalibeyoğlu H
Department of Chemistry
Kafkas University
36100 Kars, Turkey

Abstract

1H-1,2,4-triazole has been theoretically studied. All theoretical calculations have been carried out by using Density Functional Theory (DFT) and Hartree-Fock (HF) methods. The vibrational frequencies were calculated by using HF/6-31G(d,p) and DFT(B3LYP)/6-31G(d,p) basis sets in ground state. The UV-vis (ethanol), Proton Nuclear Magnetic Resonance (1H-NMR) and Carbon-13 Nuclear Magnetic Resonance (13C-NMR) spectra of title molecule have been recorded. The 1H and 13C-NMR chemical shifts of the title molecule were calculated by the GIAO method and compared with experimental results. Using gauge independent atomic orbital method 1H and 13C-NMR chemical shifts have been calculated and correlated with the experimental chemical shifts. The polarizability (α), hyperpolarizability (β), dipole moment along with molecular electrostatic potential surface have been calculated. The molecular electrostatic potential (MEP) map was calculated to assign reactive site on the surface of the molecule. The calculated electronic, structural (bond lengths and bond angles) and several thermodynamic parameters, molecular electrostatic potential (MEP) map of the compound were performed using the Hartree-Fock (HF) and density functional method (DFT/B3LYP) with 6-31G(d,p) basis set.

Keywords

1H-1,2,4-triazol-5-one, GIAO, DFT/HF, 6-31G(d,p) basis set

Introduction

4-Amino-1H-1,2,4-triazole and their derivatives are reported to possess a wide spectrum of biological activities such as antifungal, antibacterial, anticancer, anti-inflammatory and antitumor properties [1-13]. During the past two decades, considerable attention has been paid to the chemistry and computational chemical calculations of 1,2,4-triazole and their derivatives. That’s why these methods have been commonly used the prediction of many properties in the chemical systems. The computational chemical models are widely used design of functional materials. Also, many authors have studied the structure, spectroscopic, electronic and thermodynamic parameters of many organic compounds by using theoretical calculation methods [13-18].

The derivatives of 1,2,4-triazole are known to exhibit many biological activities. Hence, various 1,2,4-triazole and their derivatives have been theoretically analyzed [18-21]. Reliable results consistent with experimental results have been obtained for 1,2,4-triazole and their derivatives [21-25]. For this purpose, firstly, all quantum chemical calculations of target compound have been carried out by using B3LYP/6-31G(d,p) and HF/6-31G(d,p) methods. The DFT/B3LYP and HF methods are known to be the most widely used methods in many reported references [26,27]. Also, the vibrational frequencies and calculated structural parameters (bond lengths and bond angles), electronic, thermodynamic parameters, gauge including atomic orbital (GIAO) 1H and 13C chemical shift values, UV-vis, HOMO-LUMO energies, charge distributions, total static dipole moment (μ), the mean polizability (<α>), the anisotropy of the polarizability (Δα), the mean first-order hyperpolarizability (<β>), electronegativity(χ), hardness(η), molecular electrostatic potential maps (MEP) of target molecule were calculated by using the optimized structures with B3LYP/6-31G(d,p) and HF/6-31G(d,p) basis sets in ground state. The vibrational frequencies of the title molecule were related with the spectral data obtained with DFT/B3LYP and HF 6-31G(d,p) basis sets. In the identification of calculated IR data was used the veda4f program [28]. The calculated vibrational frequencies were compared with their experimental data.

Material and Methods

Theoretical

The quantum chemical calculations of target molecule were performed by using Gaussian 09W [29] and GaussView [30] software. The molecular geometry of title compound was optimized using density functional theory (DFT/B3LYP) and hartree fock (HF) methods with the 6-31G(d,p) basis set in ground state. From the optimized geometry, structural (bond lengths and bond angles), 1H and 13C-NMR chemical shift values, UV-Vis values, total energy, molecular electrostatic potential (MEP) map, dipole moment and Mulliken atomic charges, vibrational frequencies and HOMO–LUMO energies of the molecule were calculated with B3LYP/ HF 6-31G(d,p) levels. The IR, Proton Nuclear Magnetic Resonance (1H-NMR), Carbon-13 Nuclear Magnetic Resonance (13C-NMR) and UV-vis (ethanol) spectra of target molecule have been recorded. The veda4f program was used for the identification of the calculated IR data [28]. The gauge independent atomic orbital (GIAO) 1H and 13C-NMR chemical shift values was calculated at B3LYP/6-31G(d,p) and HF/6-31G(d,p) levels [31,32]. The theoretical UV-vis spectral values were carried out using TD-DFT method in ethanol solvent. The experimental spectra values of this compound obtained from 1H and 13C-NMR spectra were compared to the calculated results from the DFT/B3LYP and HF 6-31G(d,p) basis sets.

Optimized geometries

2-(3-Cyclopropyl-4,5-dihydro-1H-1,2,4-triazol-5-on-4-yl-iminomethyl) benzoic acid was optimized by means of DFT(B3LYP)/HF methods with 6-31G(d,p) basis set. The optimized geometric structure of 2-(3-cyclopropyl-4,5-dihydro-1H-1,2,4-triazol-5-on-4-yl-iminomethyl) benzoic acid is shown in Figure 1. The geometric parameters (bond angels and bond lengths), Mulliken atomic charges of 2-(3-cyclopropyl-4,5-dihydro-1H-1,2,4-triazol-5-on-4-yl-iminomethyl) benzoic acid were calculated using the DFT(B3LYP)/HF 6-31G(d,p) method. The calculated parameters are given in Tables 1-3 and Chart 1.

derpharmachemica-geometric-structure

Figure 1: The computed geometric structure of 2-(3-cyclopropyl-4,5-dihydro-1H-1,2,4-triazol-5-on-4-yl-iminomethyl) benzoic acid (DFT (B3LYP)/6-31G(d,p)

S. No. Bond Angels (0) B3LYP 6-31G(d,p) HF 6-31G(d,p)
1 C(1)-N(27)-N(26) 104.633 105
2 C(1)-N(28)-N(29) 121.645 121.404
3 C(1)-N(28)-C(2) 108.268 108.133
4 C(1)-C(10)-H(20) 113.423 113.89
5 C(1)-C(10)-C(11) 119.225 119.18
6 C(1)-C(10)-C(12) 119.217 108.291
7 H(20)-C(10)-C(11) 118.069 118.209
8 C(10)-C(11)-H(21) 116.357 117.218
9 C(10)-C(11)-H(22) 117.21 116.905
10 H(21)-C(11)-H(22) 115.188 114.952
11 H(21)-C(11)-C(12) 117.677 117.938
12 H(22)-C(11)-C(12) 118.913 118.487
13 C(11)-C(12)-C(10) 60.578 60.65
14 C(11)-C(12)-H(23) 117.683 117.745
15 C(11)-C(12)-H(24) 118.99 118.984
16 H(23)-C(12)-H(24) 115.2 114.868
17 H(23)-C(12)-C(10) 116.383 117.231
18 H(24)-C(12)-C(10) 117.216 117.183
19 C(12)-C(10)-H(20) 117.578 116.731
20 N(27)-C(1)-N(28) 111.284 111.155
21 N(27)-N(26)-H(14) 120.438 120.939
22 N(26)-C(2)-O(30) 129.935 129.398
23 H(14)-N(26)-C(2) 124.993 125.2
24 O(30)-C(2)-N(28) 128.814 128.625
25 C(2)-N(28)-N(29) 130.053 130.392
26 N(28)-N(29)-C(3) 118.64 119.431
27 N(29)-C(3)-H(15) 122.026 122.026
28 N(29)-C(3)-C(4) 118.482 118.482
29 H(15)-C(3)-C(4) 119.489 119.489
30 C(3)-C(4)-C(5) 122.991 122.991
31 C(4)-C(5)-C(13) 126.052 126.052
32 C(3)-C(4)-C(9) 118.891 118.891
33 C(5)-C(13)-O(31) 123.874 123.874
34 C(5)-C(13)-O(32) 114.44 114.44
35 O(31)-C(13)-O(32) 121.65 121.65
36 C(13)-O(32)-H(25) 106.072 106.072
37 C(4)-C(5)-C(6) 119.621 119.621
38 C(13)-C(5)-C(6) 114.322 114.322
39 C(5)-C(6)-H(16) 117.747 117.747
40 C(5)-C(6)-C(7) 121.264 121.264
41 H(16)-C(6)-C(7) 120.987 120.987
42 C(6)-C(7)-H(17) 120.073 120.073
43 C(6)-C(7)-C(8) 119.396 119.396
44 H(17)-C(7)-C(8) 120.531 120.987
45 C(7)-C(8)-H(18) 120.246 120.073
46 C(7)-C(8)-C(9) 120.019 119.396
47 H(18)-C(8)-C(9) 119.727 119.727
48 C(8)-C(9)-C(4) 121.634 121.634
49 C(8)-C(9)-H(19) 120.385 120.385
50 H(19)-C(9)-C(4) 117.973 117.973

Table 1: The calculated bond angles (0) of title compound (6-31G(d,p) B3LYP/HF)

S. No. Bond Lengths B3LYP 6-31G(d,p) HF 6-31G (d,p)
1 C(1)-N(28) 1.39 1.38
2 C(1)-N(27) 1.31 1.27
3 C(1)-C(10) 1.47 1.48
4 C(10)-H(20) 1.08 1.07
5 C(10)-C(11) 1.52 1.5
6 C(11)-H(21) 1.09 1.07
7 C(11)-H(22) 1.08 1.08
8 C(11)-C(12) 1.5 1.49
9 C(12)-H(23) 1.09 1.08
10 C(12)-H(24) 1.09 1.08
11 C(12)-C(10) 1.52 1.51
12 N(27)-N(26) 1.38 1.37
13 N(26)-H(14) 1.01 1
14 N(26)-C(2) 1.37 1.35
15 C(2)-O(30) 1.22 1.22
16 C(2)-N(28) 1.42 1.42
17 N(28)-N(29) 1.37 1.37
18 N(29)-C(3) 1.29 1.26
19 C(3)-H(15) 1.08 1.08
20 C(3)-C(4) 1.48 1.49
21 C(4)-C(5) 1.42 1.4
22 C(5)-C(13) 1.5 1.5
23 C(13)-O(31) 1.22 1.19
24 C(13)-O(32) 1.35 1.33
25 O(32)-H(25) 0.97 0.95
26 C(5)-C(6) 1.4 1.39
27 C(6)-H(16) 1.08 1.07
28 C(6)-C(7) 1.39 1.38
29 C(7)-H(17) 1.09 1.07
30 C(7)-C(8) 1.39 1.38
31 C(8)-H(18) 1.09 1.08
32 C(8)-C(9) 1.39 1.38
33 C(9)-H(19) 1.08 1.07
34 C(9)-C(4) 1.41 1.39

Table 2: The calculated bond lengths (A0) of title compound (6-31G(d,p) B3LYP/HF)

Atoms DFT HF Atoms DFT HF
C1 0.59 0.65 H17 0.10 0.17
C2 0.82 1.05 H18 0.10 0.16
C3 0.13 0.18 H19 0.11 0.18
C4 -0.05 -0.04 H20 0.13 0.18
C5 -0.17 -0.15 H21 0.14 0.17
C6 -0.10 -0.11 H22 0.12 0.14
C7 -0.09 -0.15 H23 0.14 0.15
C8 -0.08 -0.13 H24 0.12 0.14
C9 -0.10 -0.13 H25 0.33 0.37
C10 -0.14 -0.20 N26 -0.43 -0.56
C11 -0.21 -0.25 N27 -0,37 -0.37
C12 -0.21 -0.24 N28 -0.45 -0.65
C13 0.53 0.79 N29 -0.32 -0.30
H14 0.29 0.34 O30 -0.54 -0.66
H15 0.18 0.24 O31 -0.47 -0.56
H16 0.13 0.20 O32 -0.49 -0.61

Table 3: The calculated Mulliken atomic charges of title compound

derpharmachemica-atomic-charges

Chart 1: Graphics of the calculated Mulliken atomic charges of title compound

The calculated C4-C5, C5-C6, C6-C7, C7-C8, C8-C9, C9-C4 bond lengths of benzene rings in this compound are [1.42/1.40 A0], [1.40/1.39 A0], [1.39/1.38 A0 ], [1.39/1.39 A0], [1.39/1.38 A0] and [1.41/1.38 A0], respectively. The Ar(C)-Ar(C) bond lengths of benzene rings are generally observed at 1.34-1.53 A0 in literature [33,34]. The calculated C-H bond lengths of the compound are about 1.08 A0 and the C-H bond lengths in literature are 1.09 A0 [33,34]. Also, the calculated N26-C2 bond length in 1,2,4-triazole-5-one ring is [1.37/1.35 A0]. It has been recorded that it has bond length between single bonded N-N and double bonded N=N due to resonance. The same bond length in literature is recorded as between 1.29-1.47 A0 [33,34]. Compared with the bond lengths in the literature, the results show that the molecular structure is very well.

It has been recorded that the electronegative N and O atoms have negative atomic charge values in gas phase. The carbon atoms surrounded with electronegative atoms have positive atomic charge values in gas phase. The C1 atom which is surrounded with two electronegative atoms (N, N), C1 atom surrrounded with three electronegative atoms (N, N, O) have the highest positive charges values. All hydrogen atoms of the compound have positive atomic charge values (Table 3 and Chart 1).

NMR, IR and UV-vis spectra

The GIAO 1H and 13C chemical shift, experimental and calculated IR, UV-vis values were determined by employing DFT(B3LYP)/HF 6-31G(d,p) method. The calculational and experimental results are given in Figures 2 and 3, Tables 4-7 and Chart 2.

derpharmachemica-title-compound

Figure 2: Experimental (a) and theoretical (6-31G(d,p) DFT (b)/HF (c) IR spectra of title compound

derpharmachemica-spectra-title

Figure 3: Experimental (a) and theoretical (6-31G(d,p) DFT/HF) UV-vis spectra of title compound

  δExp. δcal. HF (Vacum) δcal. HF (DMSO) Different Different (DMSO) δcal. B3LYP (Vacum) δcal. B3LYP (DMSO) Different Different (DMSO)
C1 148.25 154.23 155.38 -5.98 -7.13 148.1 149.65 0.15 -1.40
C2 151.15 151.77 152.56 -0.62 -1.41 145.78 146.57 5.37 4.58
C3 152.86 154.85 155.14 -1.99 -2.28 149.76 150.43 3.10 2.43
C4 133.67 140.95 140.35 -7.28 -6.68 134.61 133.81 -0.94 -0.14
C5 130.73 134.4 133.92 -3.67 -3.19 124.83 124.27 5.90 6.46
C6 132.05 138.14 137.83 -6.09 -5.78 131.73 131.34 0.32 0.71
C7 130.21 132.43 133.8 -2.22 -3.59 124.57 125.8 5.64 4.41
C8 131.52 135.01 136.61 -3.49 -5.09 130.4 131.91 1.12 -0.39
C9 126.76 129.91 130.34 -3.15 -3.58 123.67 124.02 3.09 2.74
C10 5.46 16.52 16.55 -11.06 -11.09 1.7 1.81 3.76 3.65
C11 6.38 20.52 20.72 -14.14 -14.34 4.07 4.44 2.31 1.94
C12 6.38 22.43 22.66 -16.05 -16.28 5.38 5.22 1.00 1.16
C13 167.75 167.95 169.2 -0.20 -1.45 157.52 158.95 10.23 8.80
H14 11.78 7.84 8.35 3.94 3.43 7.1 7.56 4.68 4.22
H15 10.40 12.01 12 -1.61 -1.60 10.92 10.87 -0.52 -0.47
H16 8.03 9.28 9.25 -1.25 -1.22 9.13 9.11 -1.10 -1.08
H17 7.63 8.36 8.62 -0.73 -0.99 8.09 8.37 -0.46 -0.74
H18 7.65 8.42 8.71 -0.77 -1.06 8.23 8.54 -0.58 -0.89
H19 7.92 9.24 9.35 -1.32 -1.43 8.55 8.69 -0.63 -0.77
H20 2.12 3.17 3.25 -1.05 -1.13 2.16 2.29 -0.04 -0.17
H21 0.96 2.01 1.93 -1.05 -0.97 1.64 1.5 -0.68 -0.54
H22 0.96 1.85 2.08 -0.89 -1.12 0.94 1.16 0.02 -0.20
H23 0.96 1.82 1.78 -0.86 -0.82 0.75 0.79 0.21 0.17
H24 0.96 1.88 2.09 -0.92 -1.13 1.01 1.2 -0.05 -0.24
H25 11.78 7.06 7.6 4.72 4.18 6.2 6.75 5.58 5.03

Table 4: The calculated 1H and 13C-NMR isotropic chemical shifts of title compound (with respect to TMS, all values in ppm) (6-31G(d,p))

S. No. Vibration Frequencies HF B3LYP
1 τ NCCC (18), τ CCCN(28) 11 13
2 τ NCCC(41), τ CCCN(25) 21 29
3 τ OCCC(45) 39 39
4 τ NNCN(13), τ NCNN(31), 57 55
5 δ NCC(15) 67 71
6 τ CNNC(39) 100 94
7 δ CCC(11), δ CCN(11), τ OCCC(11), τ CCCC(12) 116 121
8 τ CNNC(17) 139 137
9 δ CCN(21), τ CNNC(12), τ CCCC(12) 152 166
10 δ CNN(13), τ CCCC(17) 202 202
11 δ NCC(10), δ CCC(21), τ CCCN(11) 211 217
12 τ CNNC(32) 227 236
13 τ NCNN(21), τ CCCC(10) 249 263
14 δ CCC(17), δ OCC(29) 279 284
15 τ NCNN(11), τ NNCN(28), τ CCCC(18) 323 334
16 δ CCC(10) 360 385
17 ν CC(13), δ CCC(13), δ OCO(11) 377 389
18 τ CCCN(12), τ HNNC(10), τ NNCN(30) 379 396
19 δ NNC(10), τ CCCC(24) 412 435
20 δ CCC(11), τ CCCC(21) 443 466
21 τ HNNC(54) 470 491
22 δ OCC(17), τ CCCC(14) 516 533
23 δ OCC(10), τ CCCC(14), τ HCCC(10) 543 570
24 δ CCC(19) 581 598
25 τ HOCC(75) 604 608
26 δ OCN(17), δ CCC(16) 620 644
27 δ CCC(26), δ OCO(36) 632 661
28 ν CC(12), δ CCN(18) 671 684
29 τ CNNC(17), τ ONNC(15) 694 748
30 τ CCCC(29), τ ONNC(30) 715 751
31 τ NNCN(15), τ ONNC(39) 722 774
32 ν CC(12), δ OCO(11), δ CCC(16) 745 801
33 τ CCCC(12), τ HCCC(47) 765 808
34 ν NC(11), δ CNN(26) 787 821
35 δ HCC(46) 797 823
36 τ HCCC(28), τ ONNC(20) 802 852
37 δ CCC(17), τ HCCN(36) 821 859
38 ν NN(14), δ CCC(17), δ NCN(10) 824 863
39 ν CC(12), δ NNC(19), δ NCC(13), δ CCC(13) 877 915
40 ν CC(33), δ CCC(12), τ HCCC(11) 897 931
41 τ HCCC(69) 903 965
42 ν CC(28), δ CCC(15), τ HCCN(35) 909 978
43 τ HCCC(87) 978 1054
44 τ CCCC(13), τ HCNN(26), τ HCCC(44) 996 1078
45 τ HCNN(59), τ HCCC(20) 1003 1081
46 ν CC(10), δ NNC(22) 1026 1087
47 ν NN(10), τ HCCN(36) 1054 1092
48 ν CC(46), δ HCC(17) 1060 1115
49 τ HCCC(33), τ HCCN(10) 1070 1133
50 τ HCCC(28), τ HCCN(45) 1083 1136
51 ν CC(10), δ CCC(25), δ HCC(16) 1095 1161
52 τ HCCN(33) 1125 1164
53 ν OC(30), δ HCC(15), ν CC(11) 1127 1181
54 ν NN(24), τ HCCN(13) 1136 1183
55 ν CC(10), δ HCC(76) 1180 1192
56 ν CC(10), δ HOC(41) 1198 1248
57 δ HCC(72) 1202 1251
58 ν NC(18), δ HCC(13) 1203 1255
59 ν CC(53) 1215 1264
60 ν CC(12), ν NC(10) 1235 1279
61 ν NN(10), δ CNN(11) 1271 1292
62 δ HCC(40) 1291 1343
63 ν NC(18), ν NN(10), δ HCN(16) 1326 1358
64 ν CC(49) 1339 1420
65 ν OC(20), ν CC(11), δ HOC(26), δ OCO(14) 1370 1440
66 ν NC(12), δ HNN(65) 1383 1471
67 δ HCN(52) 1421 1484
68 δ HCH(97) 1462 1521
69 δ HCC(18), δ HCH(16) 1472 1535
70 ν CC(11), δ HCC(23), δ HCH(12) 1475 1537
71 ν CC(13), δ HCC(11), δ HCH(45) 1506 1577
72 δ HCC(25), δ HCH(13), δ CCC(13) 1513 1587
73 ν CC(29), δ CCC(10) 1600 1681
74 ν NC(45) 1624 1716
75 ν NC(31), ν CC(12) 1633 1774
76 ν NC(39), ν CC(16) 1655 1810
77 ν OC(44) 1794 1878
78 ν OC(39), ν NC(12) 1808 1909
79 ν CH(58) 3117 3140
80 ν CH(56) 3120 3149
81 ν CH(30) 3159 3190
82 ν CH(61) 3175 3207
83 ν CH(39) 3188 3208
84 ν CH(58) 3194 3222
85 ν CH(55) 3197 3232
86 ν CH(53) 3203 3236
87 ν CH(26) 3212 3238
88 ν CH(27) 3217 3274
89 ν NH(100) 3664 3763
90 ν OH(100) 3720 3926

Table 5: The calculated IR frequencies of title compound (6-31G(d,p))

Experimental Vibrations IR (cm-1)
ν OC 1263
ν C=C 1591
ν C=N 1607
ν C=O 1683
ν C=O 1698
ν =CH 3057
ν NH 3125
ν OH 3178

Table 6: The experimental IR frequencies of title compound

Experimental (nm) λ (nm) HF/B3LYP 6-31G(d,p) Excitation Energy (eV) HF/B3LYP 6-31G(d,p) f (osillatör strengths) HF/B3LYP 6-31G(d,p)
308 235.61/335.03 5.2622/3.7007 0.5106/0.1245
262 230.87/316.19 5.3702/3.9211 0.1272/0.1771
232 216.64/303.51 5.7232/4.0850 0.0467/0.0010

Table 7: The experimental and calculated UV-vis values (HF/B3LYP 6-31G(d,p)) of title compound

derpharmachemica-shifts-values

Chart 2: Comparison of experimental/theoretical 1H and 13C-NMR chemical shifts values of title compound with 6-31G(d,p) B3LYP/HF (Vacum/DMSO) methods

The GIAO 1H and 13C chemical shift values in gas phase/DMSO solvent (with respect to TMS) of title compound were calculated using the DFT (B3LYP) and Hartree Fock (HF) methods with 6-31G(d,p) basis set. The calculated and experimental data are shown in Table 4.

The calculated 1H chemical shift values are observed to be 0.94-10.92/1.82-12.01 ppm in gas phase and 0.79-10.87/1.78-12.00 in DMSO solvent at DFT (B3LYP)/HF methods, while the experimental parameters are calculated 0.96-11.78 ppm with 6-31G(d,p) basis set. Aromatic C-H signals were observed at 7.63-8.03 ppm. These signals were calculated 8.09-9.13/8.36-9.28 in gas phase and 8.37-9.11/8.62-9.25 ppm in DMSO solvent at B3LYP/HF levels. The cyclopropyl protons of this compound were observed at 0.96 ppm. These were calculated as 0.72-1.64/1.82-2.01 ppm in gas phase and 0.79-1.50/1.78-2.09 ppm in DMSO solvent at B3LYP/HF levels. The O-H signal was observed at 11.78 ppm. This signal was calculated as 6.20/7.06 ppm at gas phase and 6.75/7.60 ppm in DMSO solvent at B3LYP/HF levels. The N-H signal was observed at 11.78 ppm but these signals were observed at 7.1/7.84 ppm in gas phase and 7.56-7.84 ppm in DMSO solvent at B3LYP/HF levels. There is a slight difference between theoretical and experimental N-H signal because N-H proton of 4,5-dihydro-1H-1,2,4-triazol-5-one ring was displayed the acidic character.

The 13C-NMR chemical shift values of the title compounds are observed to be 1.70-157.72/20.52-167.95 ppm in gas phase and 1.81-158.95/20.72-169.20 in DMSO solvent at DFT (B3LYP)/HF methods, while the experimental parameters are calculated 5.46-167.75 ppm with 6-31G(d,p) basis set. As a result of, the R2 values of title compound were evaluated and 13C and 1H-NMR chemical shift values of title compound were plotted graphs (Chart 2). Theoretical and experimental between 13C and 1H-NMR chemical shifts ratios of title compound were observed a linear correlation. It is such a relationship between R-values of title compound; B3LYP(DFT)/HF 6-31G(d,p)Vacum:1H: 0.7750, 13C: 0.9986, B3LYP(DFT)/HF 6-31G(d,p)DMSO: 1H: 0.8111 13C: 0.9988.

The experimental O-H, N-H, C-H, C=O stretching vibrations were given in Table 6. There is a slight difference between theoretical vibrational and experimental frequencies. Theoretical vibrational frequencies for title compound are generally closer to the experimental frequencies.

The experimental absorption wavelenghts in ethanol solvent of title compound were recorded as 308, 262, 232 nm respectively. The excitation energies, oscillator strengths (ƒ) and absorption wavelengths (λ) of UV–vis electron absorption spectroscopy in ethanol solvent of title molecule have been calculated by using B3LYP/HF methods with 6-31G(d,p) basis set and were given in Figure 3 and Table 7. The calculated UV-vis values of title compound are in a very good agreement with the experimental values.

Electronic and thermodynamics properties, homo-lumo energies

The energy levels and distributions of HOMO and LUMO were calculated at DFT(B3LYP)/HF 6-31G(d,p) level for title compound. Energies of HOMO, LUMO were recorded as -7.649 -5.275 and 7.852 -5.201 eV B3LYP and HF/6-31G(d,p), respectively. Also, The molecular softness (S), hardness (η), electronegativity (χ), chemical potential (Pi), ionization potential (I), electron affinity (A), electrophilic (ω) and nucleophilic index (IP) were calculated by using HOMO and LUMO energies (Table 8). The ΔEH-L (energy gap) energies are 2.235/2.651 eV at B3LYP/HF level, respectively (Figure 4).

  B3LYP (6-31G(d,p)) Hartree Ev Kcal/mol Kj/mol
  LUMO -0.194 -5.275 -121.635 -508.927
  HOMO -0.281 -7.649 -176.404 -738.083
A Electron Affinity 0.194 5.275 121.635 508.927
I Ionization Potential 0.281 7.649 176.404 738.083
ΔE Energy Gap 0.087 2.375 54.769 229.156
χ Electronegativity 0.237 6.462 149.020 623.505
Pi Chemical Potential -0.237 -6.462 -149.020 -623.505
ω Electrophilic Index 0.001 0.033 0.772 3.231
IP Nucleophilic Index -0.010 -0.282 -6.503 -27.210
S Molecular Softness 22.914 623.519 14.378.914 60.162.005
η Molecular Hardness 0.044 1.187 27.385 114.578
  HF (6-31G(d,p)) Hartree Ev Kcal/mol Kj/mol
  LUMO -0.191 -5.201 -119.947 -501.864
  HOMO -0.289 -7.852 -181.072 -757.614
A Electron Affinity 0.191 5.201 119.947 501.864
I Ionization Potential 0.289 7.852 181.072 757.614
ΔE Energy Gap 0.097 2.651 61.125 255.750
χ Electronegativity 0.240 6.527 150.510 629.739
Pi Chemical Potential -0.240 -6.527 -150.510 -629.739
ω Electrophilic Index 0.001 0.038 0.879 3.678
IP Nucleophilic Index -0.012 -0.318 -7.331 -30.671
S Molecular Softness 20.532 558.684 12.883.749 53.906.170
η Molecular Hardness 0.049 1.325 30.563 127.875

Table 8: The calculated electronic properties of title compound (6-31G(d,p) B3LYP/HF)

derpharmachemica-energies

Figure 4: 3D plots of HOMO-LUMO energies of title compound at the B3LYP/HF 6-31G(d,p)

The dipole moment values of title compound were computed as 0.581/0.606 D for DFT(B3LYP)/HF methods with the 6-31G(d,p) basis set. The results were given in Table 9. The highest dipole moment is recorded as μz component. The mean polizability (<α>) and the mean first-order hyperpolarizability (<β>) and are calculated -47.160 × 10-24 esu/23,088 × 10-24 esu and 8.107 × 10-30 esu/3.169 × 10-30 esu for B3LYP/HF, respectively. It was found that the β values at B3LYP/HF methods of title compound is higher than that of urea.

  B3LYP (6-31G(d,p)) HF(6-31G(d,p))
µx -1.558 Debye 1.141 Debye
µy 2.599 Debye 3.240 Debye
µz 0.581 Debye 0.606 Debye
µToplam 3.085 Debye 3.488 Debye
αxx -116.52 a,u, 31.522 a.u.
αyy -26.19 a.u. 24.379 a.u.
αzz 1.24 a.u. 13.362 a.u.
Α -47.160 × 10-24 esu 23.088 × 10-24 esu
∆α 106.71810-24 esu 15.846 × 10-24 esu
Βx -7850.88 a.u. 3071.51 a.u.
βy 1966.29 a.u. 409.35 a.u.
βz -463.44 a.u. -663.47 a.u.
βxxx -2361.58 a.u. 189.72 a.u.
βxxy -125.85 a.u. 89.16 a.u.
βxyy -9.83 a.u. 189.72 a.u.
βyyy -137.92 a.u. -20.12 a.u.
βxxz 76.32 a.u. 6.64 a.u.
βxyz -13.01 a.u. 9.71 a.u.
βyyz 17.39 a.u. -40.84 a.u.
βxzz -90.96 a.u. -12.44 a.u.
βyzz -40.22 a.u. -20.12 a.u.
βzzz 62.80 a.u. -45.08 a.u.
β 8.107 × 10-30 esu 3.169 × 10-30 esu

Table 9: The mean polizability (<α>), the anisotropy of the polarizability (Δα), the mean first-order hyperpolarizability (<β>), dipole moment values of title compound

The MEP map of title compound is shown in Figure 5. The MEP map shows that the positive potential sites are around the hydrogen as well as the negative potential sites on electronegative oxygen, nitrogen atoms. Also, thermodynamic properties of title compound are given in Table 10.

derpharmachemica-molecular-surfaces

Figure 5: The calculated molecular surfaces of title compound

Rotational temperatures (Kelvin) DFT HF
A 0.02847 0.02796
B 0.00917 0.00936
C 0.00721 0.00773
Rotational constants (GHZ)  
A 0.59328 0.5826
B 0.19116 0.19497
C 0.1503 0.16112
Zero-point vibrational energy (Kcal/Mol) 153.21673 165.36306
Thermal correction to Energy 0.261506 0.279787
Thermal correction to Enthalpy 0.26245 0.280731
Thermal correction to Gibbs Free Energy 0.195555 0.216273
Sum of electronic and zero-point Energies -947.016165 -941.378701
Sum of electronic and thermal Energies -946.998826 -941.362437
Sum of electronic and thermal Enthalpies 946.997882 -941.361493
Sum of electronic and thermal Free Energies -947.064777 941.42595
Thermal Energies E (Kcal/mol)  
Translational 0.889 0.889
Rotational 0.889 0.889
Vibrational 162.320 173.791
Total 164.097 175.569
Thermal Capacity CV (Cal/Mol-Kelvin)  
Translational 2.981 2.981
Rotational 2.981 2.981
Vibrational 59.289 54.379
Total 65.251 60.34
Entropy S (Cal/Mol-Kelvin)  
Translational 42.702 42.702
Rotational 34.199 34.129
Vibrational 63.891 58.833
Total 140.792 135.663

Table 10: The calculated thermodynamics parameters of title compound (6-31G(d,p) B3LYP/HF)

Conclusion

In this study, the geometric, thermodynamics, spectroscopic and electronic values of title compound have been calculated by using DFT (B3LYP) and HF methods with the 6-31G(d,p) basis sets. The UV-vis, IR, 1H- and 13C- NMR spectra have been obtained and compared with the experimental spectroscopic values. The theoretical calculated spectra values were found good agreement with experimental UV-vis, IR, 1H- and 13C- NMR spectra values. The value of the energy gap between the HOMO-LUMO energies was determined. Geometric parameters; bond angels and bond lengths were compared with experimental values obtained from literature [33,34]. All results showed that the calculated spectroscopic, geometric, thermodynamics and electronic parameters obtained by B3LYP/6-31G(d,p) method had a better agreement with the experimental values than HF/6-31G(d,p) method.

References

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