Synthesis, structure and antibacterial activity of dinitrosyl iron complexes (DNICs) dimers functionalized with 5-(nitrophenyl) -4-H-1,2,4-triazole-3-thiolyls

Abstract

This work aims at the synthesis and investigation of a new series of antibacterial agents, viz dimers of dinitrosyl iron complexes (DNICs) of [Fe2(SR)2(NO)4] composition, where R is 5-(2-nitrophenyl)-4-H-1,2,4-triazole-3-thiolyl (I), 5-(3-nitrophenyl)-4-H-1,2,4-triazole-3-thiolyl (II), 5-(4-nitrophenyl)-4-H-1,2,4-triazole-3-thiolyl (III), that are nitric oxide (NO) donors, easily obtained by replacement of thiosulfate ligands in [Fe(S2O3)2(NO)2]2- anion. Based on investigation of the structures of I and its isostructural analogs II and III (X-ray analysis, quantum-chemical calculations in the frame of DFT using NBO and QTAIM methods), data have been obtained on molecular interactions stabilizing DNIC dimer of µ–N–C–S structural type functionalized by 5-(2-nitrophenyl)-4-H-1,2,4-triazole-3-thiolyl. NBO calculations provided the assessment of bond energy for the Fe-S and Fe-N bonds incorporated in the µ–N–C–S bridge. From QTAIM analysis, detailed information on the nature and covalence of the forming bonds has been obtained. Assessment of antibacterial activity of I-III with respect to gram-negative (Escherichia coli) and gram-positive (Micrococcus luteus) bacteria has been performed.