Multistimuli Luminescence and Anthelmintic Activity of Zn(II) Complexes Based on 1H-Benzimidazole-2-yl Hydrazone Ligands

Three novel Zn(II) mononuclear complexes with the general formula ZnL2Cl2 (L = 2-(4-R-phenylmethylene)benzimidazol-2-hydrazines; R-H (1), R-CH3 (2), and R-OCH3 (3)) were synthesized and fully characterized by various means. These complexes demonstrate excitation-dependent emission, which is detected by a change in the emission color (from blue to green) upon an increase in the excitation wavelength. Moreover complex 1 shows reversible mechanochromic luminescence behavior due to the reversible loss of solvated methanol molecules upon the intense grinding of crystals. In addition, 1 exhibits vapochromic properties, which originate from the adsorption methanol vapor on the crystal surface. The strengthening of anthelmintic activity at the transition from free hydrazones to zinc-based complexes is shown.