Excited-State Pathways of Four-Coordinate N,C-Chelate Organoboron Dyes

Abstract

The excited-state behavior of four-coordinate N,C-chelate organoboron dyes, based on arylisoquinoline ligands with varying degree of charge-transfer character, was characterized. Data related to excited triplet state formation, oxygen quenching, and singlet-oxygen formation were obtained. The results jointly rationalize the previously observed high photostability of the dyes in air-equilibrated media. Furthermore, femtosecond transient absorption experiments enabled the spectroscopic visualization of the excited intramolecular charge transfer (ICT) state that gives rise to the fluorescence of the dyes.