Co–HOAT Complexes Change Their Antibacterial and Physicochemical Properties with Morphological Evolution

Abstract

Antibacterial coordination compounds have attracted tremendous attention ascribed to their excellent designability. However, how the morphological evolution of these complexes influences their antibacterial and physicochemical properties has never been investigated based on proposed mechanisms. Thus, a series of Co–HOAT coordination compounds synthesized from inorganic to organic cobalt sources were prepared. We propose that with the same HOAT ligand, inorganic Co–HOAT nanosheets possess higher sterilization rates compared with organic Co–HOAT nanoparticles. This is explained by the different steric hindrance of cobalt sources. Relatively small steric hindrance could lead to ample active positions for inorganic cobalt ions to coordinate with both N and O atoms in HOAT. Meanwhile, organic Co2+ ions could only unite with N atoms in HOAT. Furthermore, by theoretical calculation, cobalt ions with adequate coordination sites are beneficial for developing nanosheet morphologies. Meanwhile, the Co–HOAT complexes with a lower density of electron clouds present higher sterilization rates due to the anchoring effect of electrostatic attraction. The proposed mechanism is that Co2+ released from compounds could cause multiple toxic effects to bacteria anchored by Co–HOATs. Finally, Co–HOATs’ behaviors have excellent antimicrobial properties without environmental limitations. In conclusion, the Co–HOATs appear to be a potential antibacterial catalyst in the antimicrobial field.