Antibacterial and aqueous dual-responsive sensing activities of monomeric complexes with uncoordinated imidazole sites

Herein, three monomeric complexes, [Co(HL)(HCOO)(H2O)] (1), [Cd(HL)(H3CCOO)(H2O)] (2) and [Ni(H2L)(H2O)(2)(NO3)(2)] (3) (H2L = 6,6 '-di(benzimidazo-2-yl)-2,2 '-bipyridyl), were solvothermally synthesized based on a well-designed semirigid benzimidazolyl ligand. The ligand chelating one metal ion constitutes the 0-D discrete butterfly-shaped monomer with uncoordinated imidazole sites. The antimicrobial activity study showed that all the compounds displayed effective inhibition against different bacteria. The three monomeric complexes were hydrolytically stable and slightly soluble in water. Furthermore, the fluorescent monomeric complex 2 presented high selectivity and sensitivity for the detection of trace Cu2+ and Hg2+ in an aqueous solution.