A Charge Transfer Mediated Sequential Triplet Energy Transfer Model Beyond the Dexter Limit in Organic Photocatalysis.

ABSTRACT: Classical distance-dependent Dexter energy transfer models fail to account for the complex, geometry-sensitive kinetics observed in flexible and dynamically disordered organic photocatalytic systems. To resolve these persistent inconsistencies, particularly in photosensitized [2 + 2] cycloaddition reactions, we investigate how charge-transfer (CT) intermediates mediate triplet-triplet energy transfer (TTEnT) beyond the conventional Dexter framework. Through a combined approach integrating high-level multistate CASPT2 calculations, ultrafast transient absorption spectroscopy, and electrochemical analysis, we uncover two distinct and previously unrecognized TTEnT pathways: a CT trap mechanism and a CT-mediated sequential TTEnT mechanism in which electron and hole transfer steps bridge the do

SUBMITTER: Liu L 

PROVIDER: S-EPMC12648329 | biostudies-literature | 2025 Nov

REPOSITORIES: biostudies-literature