Two Ho(III) and Co(II) complexes constructed from bis(triazol‐1‐yl)benzoic acid with structurally similar carboxyl ligands: Syntheses, structures and biological activities

Abstract

Two new complexes, [Ho(L)2NO3]n (1) and [Co(L′)2Cl4]n (2) (HL = 3,5‐bis(triazol‐1‐yl)benzoic acid, HL′ = 2,4‐bis(triazol‐1‐yl)benzoic acid), have been synthesized and characterized. Interactions with DNA through absorption titration experiments, fluorescence spectra, viscosity measurements and a molecular docking study were examined. The results suggested that complexes 1 and 2 interact with DNA in a partial intercalation mode. DNA binding affinity was determined using kb values, which indicated that the binding activity of the complexes to DNA was complex 2 (kb = 1.93 × 104) > complex 1 (kb = 1.06 × 104). Gel electrophoresis assay demonstrated that the complexes have the ability to cleave pBR322 DNA. Apoptotic assay indicated that the complexes can induce programmed death of Hela cells (human cervix carcinoma cells). A cytotoxicity study indicated that complex 2 shows a greater inhibitory rate of Hela cells than complex 1 and the cytotoxicity of both 1 and 2 showed time dependence. Especially, the efficacy of complex 2 was shown to be higher than that of cisplatin at 72 h.