Crystalline nanofiber photosensitizers with twisted dual-acceptors: high light harvesting and singlet oxygen quantum yield

The development of heavy-atom-free crystalline photosensitizers is highly favorable for practical applications due to their inherent advantages in robustness, facile post-reaction removal, and recyclability. However, achieving such systems with high molar absorptivity (>50 000 M⁻¹ cm⁻¹) and singlet oxygen quantum yields (>70%) remains a critical challenge, as these properties are typically compromised by intermolecular π-π interactions in molecular systems. Herein, we present a donor-acceptor (D-A) molecule featuring a uniquely twisted dual-acceptor backbone (D-A-A-D), achieving both high molar absorptivity and efficient singlet oxygen generation in monomeric solution. Critically, this connection topology facilitates the formation of crystalline nanofibers through CH/π and electrostatic interactions while effectively suppressing π-π stacking. The resulting crystalline nanofibers exhibit exceptional solid-state photophysical properties, including remarkably high molar absorptivity (ε = 53 400 M⁻¹ cm⁻¹) and singlet oxygen quantum yield (∼72%), surpassing even their monomeric forms. These synergistic attributes enable rapid, singlet oxygen-mediated aerobic photo-oxidation of organic substrates (e.g. benzylamines, sulfides). Furthermore, the nanofibers demonstrate excellent photostability and recyclability, retaining catalytic efficiency over at least five consecutive cycles. This work establishes crystalline photosensitizers as a new paradigm for integrating high molar absorptivity, exceptional singlet oxygen generation, and long-term structural durability.