SYNTHESIS, SPECTRAL AND QUANTUM CHEMICAL RESEARCHES OF (Z)-10-(2-(4-AMINO-5-THIOXO-4,5-DIHYDRO-1H-1,2,4-TRIAZOLE-3-IL)HYDRAZONO)-9-PHENANTHRONE

Abstract

(Z)-10-(2-(4-amino-5-thioxo-4,5-dihydro-1H-1,2,4-triazole-3-il)hydrazono)-9-phenanthrone (I) was obtained by a condensation of 4-amino-5-hydrazino-4H-1,2,4-triazole-3-thiol with 9,10-phenanthrenequinone. The compound I was characterized by IR, UV-VIS, 1Н, 13С NMR and chromatography-mass spectrometry.  The electronic absorption spectra of I in aproton solvents (DMF, DMSO) are characterized by the existence of an intensive long-wave band in the range of 468 - 485 nm. The absorption maximum of a freshly prepared solution of I (485 nm) after 48 h gradually undergoes hypsochromic shift to 474 nm, and after 72 h it shifts to 468 nm. In the UV-VIS spectrum of I, at addition of NaOH the batochromic shift of a long wave band to 511 nm with a significant increase in intensity is observed. The presence of one isobestic point in the spectrum indicates the formation of a mono-anion. In the UV-VIS spectrum of I at addition of HCl solution, the long wave absorption band undergoes hypsochromic shift to 376 nm with a small decrease in intensity. In the 1Н NMR spectrum of I, in the range of 15.08 ppm a singlet signal of a proton of a hydrazo-group is observed. In the 13С NMR spectrum of I, in the range of 180.80 ppm a signal which corresponds to carbonyl C-atom is observed. Quantum chemical modeling of the electronic structure of I as well as its ionic forms was performed in the frames of the density functional theory approach (DFT) using of a hybride tri-parametric exchange Becke functional with a correlational Lee-Yang-Parr functional (B3LYP) and basis sets def2-SV(P), def2-TZV(P). According to the spectral and quantum chemical studies, in the crystalline state and saturated solution the compound I exists in the form of the thione quinone hydrazone tautomer stabilized by intramolecular hydrogen bonds. The thione tautomer is 44 kJ/mol more stable than a thiol tautomer, the transition barrier is 135 kJ/mol. However, it is not possible to exclude possibility of transition of the thione form into the thiol one in the diluted solutions. Forcitation:Polyanskaya N.A., Ryabov M.A., Strashnov P.V., Linko R.V., Davydov V.V., Kobrakov K.I., Karavaeva E.B. synthesis, spectralandquantumchemicalresearchesof (Z)-10-(2-(4-amino-5-thioxo-4,5-dihydro-1H-1,2,4-triazole-3-il)hydrazono)-9-phenanthrone. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 1. P. 55-65