DNA-Binding and Anticancer Activity of Binuclear Gold(I) Alkynyl Complexes with a Phenanthrenyl Bridging Ligand.

3,6-Diethynyl-9,10-diethoxyphenanthrene () was synthesized from phenanthrene and employed in the synthesis of the binuclear gold(I) alkynyl complexes (RP)Au(C≡C-3-[CH-9,10-diethoxy]-6-C≡C)Au(PR) (R = Ph (), Cy ()). The diyne and complexes and were characterized by NMR spectroscopy, mass spectrometry, and elemental analysis. UV-Vis spectroscopy studies of the metal complexes and precursor diyne show strong p à p* transitions in the near UV region that red shift by ca. 50 nm upon coordination at the gold centers. The emission spectrum of shows an intense fluorescence band centered at 420 nm which red shifts, slightly upon coordination of to gold. Binding studies of , and against calf thymus DNA were carried out, revealing that and have >40% stronger binding affinities than the commonly used intercalating agent ethidium bromide. The molecular docking scores of , and with B-DNA suggest a similar trend in behavior to that observed in the DNA-binding study. Unlike the ligand , promising anticancer properties for and were observed against several cell lines; the DNA binding capability of the precursor alkyne was maintained, and its anticancer efficacy enhanced by the gold centers. Such phenanthrenyl complexes could be promising candidates in certain biological applications because the two components (phenanthrenyl bridge and metal centers) can be altered independently to improve the targeting of the complex, as well as the biological and physicochemical properties.