Synthesis, structural and optical properties of 1-alkyl-2-(2’-tosylaminophenyl)-5-nitrobenzimidazoles and their zinc(II) complexes

•N, N bidentate Benzimidazole containing ligands and their Zn(II) complexes.•X-ray crystallographic analysis of ligands and Zn(II) complexes.•Optical behavior of mononuclear Zn(II) compounds.

A series of novel benzimidazole derivatives 1-alkyl-2-(2’-tosylaminophenyl)-5-nitrobenzimidazoles with common formulas HL (1–3) (R = C2H5 (1); R = n-C3H7 (2); R = n-C4H9(3)) and their mononuclear zinc(II) complexes ZnL2 (4–6) have been synthesized in a molar ratio Zn: HL = 1:2 in methanol solutions. Formulation of 1–6 is based upon satisfactory C, H, N, S elemental analyses, IR and 1H, 13C NMR spectroscopies, while the structures of 2, 3, 5, 6 were determined by X-ray single-crystal diffraction. The optical properties of 1–6 were investigated.