Parallel evolution of charge transfer and supramolecular chirality in an aggregation-induced donor-acceptor co-assembly.

Abstract

Understanding how electronic communication and chirality emerge cooperatively in supramolecular systems remains a major challenge in molecular materials science. Herein, we report an aqueous donor-acceptor co-assembly comprising a pyrene-L-histidine donor and a nitrobenzofurazan (NBD)-based acceptor that simultaneously generates charge-transfer (CT) interactions and supramolecular chirality. The donor-acceptor pair possesses a favorable frontier orbital alignment that supports intermolecular electron transfer and charge-transfer state formation. Co-assembly produced a broad CT absorption band spanning 380-650 nm together with intense induced circular dichroism signals extending into the CT region, demonstrating efficient transfer of molecular chirality from the histidine-bearing donor to the achiral acceptor. A key finding of this work is the parallel evaluation of CT absorption and supramolecular chirality under concentration-, time-, and temperature-dependent conditions. The nearly identical evolution of both responses established that charge transfer and chirality transfer are aggregation-induced, dynamically coupled phenomena arising from the same donor-acceptor architecture. Stoichiometric studies confirmed a discrete 1 : 1 complex, while FTIR, DLS, FESEM, and TCSPC analyses revealed cooperative hydrogen bonding, π-π stacking, and photoinduced electron transfer as the principal driving forces governing assembly formation.