Chlorination‐Mediated π–π Stacking Enhances the Photodynamic Properties of a NIR‐II Emitting Photosensitizer with Extended Conjugation

Abstract

AbstractNIR‐II‐emitting photosensitizers (PSs) have attracted great research interest due to their promising clinical applications in imaging‐guided photodynamic therapy (PDT). However, it is still challenging to realize highly efficient PDT on NIR‐II PSs. In this work, we develop a chlorination‐mediated π–π organizing strategy to improve the PDT of a PS with conjugation‐extended A‐D‐A architecture. The significant dipole moment of the carbon‐chlorine bond and the strong intermolecular interactions of chlorine atoms bring on compact π–π stacking in the chlorine‐substituted PS, which facilitates energy/charge transfer and promotes the photochemical reactions of PDT. Consequently, the resultant NIR‐II emitting PS exhibits a leading PDT performance with a yield of reactive oxygen species higher than that of previously reported long‐wavelength PSs. These findings will enlighten the future design of NIR‐II emitting PSs with enhanced PDT efficiency.