Light-emitting anticancer Pt-cyclometalated phenanthroimidazole complexes

Designing drugs that selectively target cancer cells while sparing healthy ones remains a major challenge in cancer chemotherapy. In this study, four new Pt-cyclometalated complexes containing a pipyridine core and varied phenanthroimidazole-based ligands were synthesized and comprehensively characterized to evaluate their potential as selective anticancer agents with reduced toxicity toward peripheral blood mononuclear cells. Through molecular engineering via substitution on the imidazole moieties, these complexes exhibit tunable emission properties, with colors ranging from blue (475 nm) to green (610 nm) and high photoluminescence quantum yields exceeding 60 %, underscoring their promise as luminescent anticancer systems. Biological evaluations, including flow cytometry, cell cycle analysis, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assays, revealed that complexes with simpler, unsubstituted imidazole frameworks displayed the strongest anticancer activity, correlating with their higher quantum yields and stronger binding affinities toward both double-stranded DNA (dsDNA) and G-quadruplex DNA (G4DNA). Overall, these findings demonstrate that phenanthroimidazole-containing Pt-cyclometalated complexes represent a promising class of light-emitting anticancer agents with potential for selective and efficient cancer therapy.