Triplet‐Forming Thionated Donor‐Acceptor Chromophores for Electrochemically Amphoteric Photosensitization

A series of piperidine-naphthalene monoimide, donor−acceptor (D−A) chromophores and their thionated derivatives were prepared. The physical properties the studied by spectroscopic electrochemical measurements DFT calculations. Relative to non-thionated counterparts, D−A display enhanced visible-light absorption 1O2-sensitization quantum yields negligible fluorescence, suggesting facile triplet formation this class molecules. This behavior originates from significant n-π* character in singlet excited state, resulting large spin-orbit coupling between singlet/triplet manifolds regardless degree D/A interactions. With electrochemically active moieties high energy, can be used as amphoteric photosensitizers catalyze reductive oxidative photoreactions with efficiency comparable Ru(bpy)32+ sensitizer. Our results demonstrate that thiocarbonylation utilized amide/imide-containing provide a wide range heavy-atom-free redox-active photosensitizers.