Light-Driven Radical Catch-and-Release with BODIPY Photocages

In this work, we present the light-induced “catch-and-release” process leveraging a reversible homolytic photocage-payload bond cleavage based on green light-activable boron dipyrromethene (BODIPY) photocages. We demonstrate that Cl payload in chloromethyl BODIPY (BODIPY-Cl) can be released via a homolytic pathway even in methanol, which usually leads to photo-SN1 reaction. Additionally, we show that the quantitative and fast homolytic photorelease of a persistent radical payload TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy) from BODIPY is four times more efficient than heterolytic photorelease of carboxylic acids. Additionally, we utilized the radical reactivity of BODIPY-Cl in free radical and RAFT polymerizations of isobornyl-acrylate, enabling both Type I photoinitiation and attachment of BODIPY to the polymer backbone.