3-Ethyl-4-(2-benzenesulfonyloxy)-benzylideneamino-4,5-dihydro-1H-1,2,4-triazol-5-one has been optimized using the DFT/B3LYP and B3PW91 methods with the 6-311G(d,p) basis set in the ground state. The vibrational (IR) frequencies, 1H and 13C NMR chemical shift values (in gas phase and in DMSO solvent), nonlinear optical properties (NLO), HOMO−LUMO analysis and molecular electrostatic potential surfaces of 3-Ethyl-4-(2-benzenesulfonyloxy)-benzylideneamino-4,5-dihydro-1H-1,2,4-triazol-5-one have been calculated using the DFT/B3LYP and DFT/B3PW91 methods with the 6-311G(d,p) basis set. IR absorption frequencies of titled molecule were calculated by same methods. Theoretically calculated IR data are multiplied with appropriate adjustment factors. The data obtained according to DFT/B3LYP and DFT/B3PW91 are formed using theoretical infrared spectrums. The veda4f program was used in defining IR data which were calculated data. 1H-NMR and 13C-NMR isotropic shift values were calculated by the method of GIAO using the program package Gaussian G09W. Experimental and theoretical values were inserted into the grafic according to equatation of δ exp=a+b. δ calc. The spectroscopic and structural data of titled molecule has been calculated by using 6-311G(d,p) basis set with DFT/B3LYP and DFT/B3PW9. The values obtained were compared with experimental values.

In this study, theoretically spectral values of 2-(3-methyl-4,5-dihydro-1H-1,2,4-triazol-5-one-4-yl-azomethine)-phenyl cinnamate was calculated according to Gaussian G09W software. These theoretical values were compared with experimental values and obtained the results are interpreted. For this purpose, firstly, 2-(3-methyl-4,5-dihydro-1H-1,2,4-triazol-5-one-4-yl-azomethine)-phenyl cinnamate molecula were optimized using B3LYP/6-311G(2d,p) basis set. Bond angles, bond lengths, dihedral angles, dipole moments, the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) energy, mulliken charges and total energy of the molecule were calculated with B3LYP/6-311G(2d,p) basis set. UV-vis values in ethanol were calculated. In addition, Theoretically calculated IR values of this compound were calculated in gas phase. The calculated IR values are multiplied with appropriate scale factors and the values obtained according to B3LYP method is obtained using theoretical infrared spectrum. The identification of calculated IR values were used veda4f program. Finally, 1H-NMR and 13C-NMR spectral values according to GIAO method was calculated in gas phase and in DMSO solvent. Theoretically and experimentally values were inserted into the graphic according to equitation of δexp=a+b. δ calc. The standard error values were found via SigmaPlot program with regression coefficient of a and b constants. The calculated and experimental results were exhibited a very good agreement.