Regulating\nthe Twisted Intramolecular Charge Transfer\nand Anti-heavy Atom Effect at Supramolecular Level for Favorable Photosensitizing\nActivity in Water

Photosensitizing\nassemblies based on twisted intramolecular charge\ntransfer (TICT) active donor–acceptor–donor (D-A-D)\nsystem <b>BrTPA-Qx</b> having bromine atoms at the periphery\nhave been developed. Through strategic incorporation of bromine atoms\nat the <i>para</i>-position to the nitrogen–carbon\nbonds of phenyl rings at the periphery, halogen–halogen interactions\nare induced in <b>BrTPA-Qx</b> nanoassemblies in H<sub>2</sub>O:DMSO (99:1) solution. Hence, the anti-heavy atom effect is induced,\nand the limitations of TICT (dark excited state) and heavy atom effect\n(triplet deactivation via radiative decay) could be overcome. Because\nof TICT and anti-heavy atom effect, supramolecular <b>BrTPA-Qx</b> nanoassemblies demonstrate high efficiency in promoting activation\nof aerial oxygen via electron and energy transfer pathways in aqueous\nmedia. The significant influence of the stabilized TICT state and\nanti-heavy-atom effect in controlling the ROS generation was validated\nthrough in-depth solvent-dependent photophysical studies and investigations\nof the structure–activity relationship in several model compounds.\nThe notable photosensitizing activity of <b>BrTPA-Qx</b> nanoassemblies\nis manifested in their ability to efficiently catalyze the oxidative\ncoupling of benzylamine (via type I and type II mechanisms), Knoevenagel\ncondensation of aromatic aldehydes (type II), and oxidative hydroxylation\nof arylboronic acids (type I) under mild conditions.