Organoplatinum(II) J‐Aggregates with Prolonged Triplet Lifetimes for Enhanced Photodynamic and Photocatalytic Therapy

Abstract J‐aggregates have demonstrated superior phototherapeutic performance compared to their monomeric counterparts. However, the underlying mechanisms for this enhancement are not fully understood. In this work, we report two near‐infrared (NIR)‐emissive organoplatinum(II) complexes, Pt‐2TPE and Pt‐2TPA , which self‐assemble into J‐aggregates via Pt‐Pt and π‐π stacking interactions. Theoretical calculations reveal that J‐aggregates possess lower LUMO energy levels and reduced singlet–triplet energy gaps compared to their monomers, indicating enhanced electron‐accepting ability and more efficient intersystem crossing (ISC). Transient absorption spectroscopy confirmed a dramatically prolonged triplet excited‐state lifetime in Pt‐2TPA J‐aggregates (5.8 µs) versus the monomer (123 ns). The efficient oxygen quenching of this long‐lived triplet excited‐state verified enhanced triplet‐state population and sensitization in the J‐aggregates. Consequently, the J‐aggregates efficiently generate Type I/II reactive oxygen species (ROS) and catalyze NADH oxidation under red light, leading to effective eradication of B16‐F10 cells under both normoxic and hypoxic conditions. Furthermore, a biotin‐modified nanoformulation ( Biotin@Pt‐2TPA ) exhibits excellent tumor accumulation and tumor growth suppression in vivo. This work provides a strategy to enhance the efficacy of photodynamic and photocatalytic therapy of platinum(II) complexes.