A novel CuII4 cluster based on Schiff base ligand: Crystal structure, efficient conversion of CO2 to cyclic carbonates and biological activity

A new tetranuclear Cu(II)-based cluster with molecular formula [Cu 4 (L) 4 ] ( 1 ) (H 2 L =(2-hydroxy-N’-[(1E)-(2-hydroxy-3-methoxyphenyl)methylidene]-3-methoxybenzoh-ydrazide) has been successfully synthesized by using solvent evaporation method and characterized by elemental analysis, infrared spectroscopy, ultraviolet spectroscopy, thermogravimetric analysis, and x-ray single crystal diffraction. Structural analysis reveals that cluster 1 is belong to triclinic system space group P -1. The central Cu(II) ion is six-coordinated, which is a regular octahedral configuration. Four Cu(II) ions and four μ 3 -O forms a cubane-like structure. Magnetic measurement indicated that cluster 1 shows weak antiferromagnetic interaction between the adjacent Cu(II) ions. Catalytic study reveals that cluster 1 can effectively catalyze the cycloaddition reaction of CO 2 and epoxides under mild conditions. Moreover, the antibacterial activities study shows that cluster 1 has stronger antibacterial activity against S. aureus, E. coli, B. subtilis and C. albicans than the H 2 L. Furthermore, the interaction of cluster 1 with DNA was investigated using UV– vis absorption, fluorescence quench spectra, C-V curve and agarose gel electrophoresis. The results showed that the binding mode was intercalation between the cluster and DNA.