Tunable emissive Ir(III) benzimidazole-quinoline hybrids as promising theranostic lead compounds

Redrado, Marta and Miñana, Miriam and Coogan, Michael and Gimeno, M. Concepción and Fernández-Moreira, Vanesa (2022) Tunable emissive Ir(III) benzimidazole-quinoline hybrids as promising theranostic lead compounds. ChemMedChem, 17 (18): e202200244. ISSN 1860-7179

Abstract

Bioactive and luminescent cyclometallated Ir(III) complexes [Ir(ppy) 2 L1 ]Cl ( 1 ) and [Ir(ppy) 2 L2 ]Cl ( 2 ) containing a benzimidazole derivative ( L1 / L2 ) as auxiliary mimic of a nucleotide have been synthesised. The emissive properties of both complexes are conditioned by the nature of L1 and L2 , rendering an orange and a green emitter respectively. Both are highly emissive with quantum yield increasing in absence of oxygen up to 0.26 ( 1 ) and 0.36 ( 2 ), suggesting their phosphorescent character. Antiproliferative activity against lung cancer A549 cells increased up to 15 times upon irradiation conditions, reaching IC 50 values in the nanomolar range (0.3 ± 0.09 μM ( 1 ) and 0.26 ± 0.14 μM ( 2 )) and pointing them as good PSs candidates for photodynamic therapy via 1 O 2 generation. Cellular biodistribution analysis by fluorescence microscopy suggest the lysosomes as the preferential accumulation organelle. Time-resolved studies showed a greatly increased cellular emission lifetime compared to the solution values, indicating binding to macromolecules or cellular structures and restriction of collision and vibrational quenching.