Design and characterization of novel pyridylbenzimidazole-based ruthenium(II) complexes, and their evaluation in singlet oxygen generation.

Abstract

Six new ruthenium(II) polypyridyl complexes incorporating pyridinyl, quinolinyl, or isoquinolinyl-benzimidazole ligands were synthesized to investigate the influence of π-conjugated mono- and bis-chelating ligands on their photophysical and electrochemical properties, and compared to the frontrunner [Ru(bpy)3](PF6)2. Their evaluation reveals that ligand π-extension modulates the ILCT and MLCT transitions, leading to red-shifted absorption and tunable excited-state redox potentials. The mononuclear complexes were further evaluated as visible-light photocatalysts through reactive oxygen species (ROS) generation and a model α-arylation reaction. These findings demonstrate that benzimidazole-based ligand engineering provides an effective strategy to tune the excited-state properties and photocatalytic behavior of ruthenium complexes.

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