Surfactant–cobalt(III) complexes: Synthesis, critical micelle concentration (CMC) determination, DNA binding, antimicrobial and cytotoxicity studies

A new class of surfactant–cobalt(III) complexes, cis-[Co(bpy) 2(C 11H 23NH 2)Cl] 2+ ( 1) and cis-[Co(phen) 2(C 11H 23NH 2)Cl] 2+ ( 2) (bpy = 2,2′-bipyridyl, phen = 1,10-phenanthroline), have been synthesized and characterized. The critical micelle concentration (CMC) values of these complexes in aqueous solution were obtained from conductance measurements. The specific conductivity data (at 298, 308, 318 and 328 K) served for the evaluation of the temperature-dependent CMC and the thermodynamics of micellization ( Δ G m 0 , Δ H m 0 and Δ S m 0 ) . The interaction between these complexes and calf thymus DNA in aqueous solution was investigated adopting electronic absorption spectroscopy, emission spectroscopy and viscosity measurements. Results suggest that the two complexes can bind to DNA via groove binding, van der Waals interactions and/or electrostatic interactions. The complexes showed moderate antibacterial and antifungal activities against certain selected microorganisms. The cytotoxic activity of the complexes on HBL-100 human breast cancer cells was determined adopting MTT assay and specific staining techniques, which revealed that the viability of the cells thus treated was significantly decreased and the cells succumbed to apoptosis as seen in the changes in the nuclear morphology and cytoplasmic features. Furthermore, the influence of complexes on normal cell lines from green monkey kidney was also determined and the results indicate that the effect is small on inhibition of viability.