Luminescent anticancer Ru(II)-arenebipyridine and phenanthroline complexes: Synthesis, characterization, DFT studies, biological interactions and cellular imaging application

Abstract

A series of ruthenium(II)-arene complexes of several bipyridine and phenanthroline derivatives have been synthesized by employing a green and efficient protocol involving water as a solvent under sonication. The structures of all the complexes were elucidated by the spectroscopic analysis. The geometry of the chlorido and PTA (1,3,5-Triaza-7-phosphaadamantane) complexes were further confirmed by DFT and single crystal XRD. The stability study in various solvents, specifically in the intracellular one was conducted. Most of the compounds exhibited significant potency and selectivity against MCF7 and HeLa cell lines with respect to normal HEK-293 cells compared to cisplatin and RAPTA-C (Ruthenium(II)-arene PTA complex). Complex [(η6-hexamethylbenzene)RuCl(κ2-N,N-4,4′-di-n-nonyl-2,2′-bpy)]Cl (3e) presented best anticancer profiles against all the human cancer cells. Interestingly, few complexes turned up to be highly fluorescent depicted by the quantum yield values. Remarkably, [(η6-p-cymene)RuCl(κ2-N,N-bpy)]Cl (3i) was identified as most significant anticancer theranostic agent interms of potency, selectivity and fluorescence quantum yield. This complex also represented itself as significant cellular imaging agent in live U-87 MG cells which was monitored by confocal microscope. Absorption and emission spectral studies of bypyridine and phenanthroline complex series revealed that the complexes interacted with calf thymus DNA through groove binding as well as intercalative mode. In addition to this, strong binding efficacy of these scaffolds wih BSA (Bovin Serum Albumin) also enhanced their transportation property inside the cells.