Driving Triplet State Population in Benzothioxanthene Imide Dyes: Let's twist!
Darío Puchán Sánchez, Pierre Josse, Nathan Plassais, Geonwoo Park, Yeasin Khan, Yejoo Park, Mathilde Seinfeld, Antoine Guyard, Magali Allain, Frédéric Gohier, Lhoussain Khrouz, Dominik Lungerich, Hyun S. Ahn, Bright Walker, Cyrille Monnereau, Clément Cabanetos, Tangui Le Bahers
Abstract
Controlling the formation of photoexcited triplet states is critical for many (photo)chemical and physical applications. Here, we demonstrate that a permanent out-of-plane distortion of the benzothioxanthene imide (BTI) dye promotes intersystem crossing by increasing spin-orbit coupling. This manipulation was achieved through a subtle chemical modification, specifically the bay-area methylation. Consequently, this simple yet efficient approach expands the catalog of known molecular engineering strategies for synthesizing heavy atom-free, dual redox-active, yet still emissive and synthetically accessible photosensitizers.