Structural influence of new fabricated CoII and CuII-diol Schiff-base complexes on catalytic epoxidizing reactions and biological efficacy

Abstract

The facile preparing procedure for diol Schiff-bases motivated us to construct a new derivative (2-(((5-nitrobenzo[d]thiazol-2-yl)imino)methyl)benzene-1,4-diol, HLdil) elucidating its complexing action toward divalent Co^II and Cu^II ions. Two new complexes were obtained of different structural features (Co(Ldil)₂ and CuLdilCl), respectively, in which their structure was confirmed by alternated spectral tools. The distinguished effect of the metal ion type and the structural features of the two complexes was examined in the catalytic and biological fields. For the catalytic purpose, at 353 K, an interesting catalytic action of Co(Ldil)₂ and CuLdilCl was explored in the selective epoxidation and esterification with acetic acid of 1,2-cyclooctene (CyO) (as representative example of olefins) within hydrogen peroxide (H₂O₂). The yielding percentages of the selective epoxide product were 87 and 89% after 5 and 4 h with the catalysts Co(Ldil)₂ and CuLdilCl, respectively. A tentative mechanistic pathway was represented regarding the influence of M^II-ions type and its complex geometrical structure. The esterification progress was accomplished with and without H₂O₂ to give two main different products catalyzed by CuLdilCl. For the biological purpose, assigning the inhibitive potential versus the proliferative rate of six different types of microorganisms, and three human cancer cell lines, the bioreactivity of HLdil, Co(Ldil)₂, and CuLdilCl was reported. Also, the viscometric/spectroscopic characteristic changes for the solutions of HLdil, Co(Ldil)₂, and CuLdilCl with calf thymus DNA solution (DNA) aimed to distinguish the mode of interaction. The evaluated microbial inhibitive zone areas in mm and (IC₅₀) half-effective concentrations versus the cancer growing up in mM were applied to elucidate their biological potential. With binding constants, chromism mode, and Gibb’s free energy, the interactive nature for HLdil, Co(Ldil)₂, and CuLdilCl with DNA was evaluated.