Experimental and quantum chemical analyses of S-benzyl β-N-(benzylidene) dithiocarbazate as biologically active agent

The NS based S-benzyl β-N-(benzylidene)dithiocarbazate (HL2) Schiff base was synthesized by 1:1 condensation method between S-benzyl dithiocarbazate and 4-Hydroxy-3-methoxybenzaldehyde. The structure of the compound was elucidated by FT-IR, Mass, ¹³C-NMR, Raman, ¹H-NMR, and UV-Vis both by spectroscopic and computational techniques. Its anti-bacterial activity is assayed against two commonly infection causing bacterial strains namely gram-positive S. aureus and gram-negative E. coli. The results showed appreciable biological activity and the activity increased with increase in concentration. Thermal stability of the ligand was carried by TGA up to 500°C, decomposes fully to give gaseous products. Theoretical investigation of HL2 has been accomplished using DFT- B3LYP quantum chemical method in combination with B3LYP exchange correlation functional. VEDAA (Vibrational energy distribution analysis) software was employed for theoretical FT-IR spectrum analysis which yielded 93 fundamental vibrational modes along with potential energy distribution percentage (PED%) showing non-linearity of HL2. Theoretically calculated parameters like UV-VIS, FT-IR, ¹HNMR, ¹³C-NMR, Raman, HOMO-LUMO energy gap and electrostatic potential were in conformity with calculated results. (author)