Advancing Two‐Photon Photodynamic Therapy Over NIR‐II Excitable Conjugated Microporous Polymer with NIR‐I Emission

Abstract The availability of second near‐infrared (NIR‐II) excitable two‐photon photosensitizers with NIR‐I emission for efficient photodynamic therapy (PDT) is limited by challenges in molecular design. In this study, a NIR‐II light‐excitable two‐photon conjugated microporous polymer ( Tph‐Dbd ) with emission in the NIR‐I region is developed. The large conjugated system and delocalized electronic structures endow Tph‐Dbd with a large two‐photon absorption cross‐section under NIR‐II light excitation. Moreover, the efficient electron acceptor and donor units within the π‐conjugated backbones result in NIR‐I emission for high signal‐to‐background ratio imaging, as well as separated highest occupied molecular orbital and lowest unoccupied molecular orbital distributions for excellent singlet oxygen generation ability. The excellent NIR‐II excitable two‐photon absorption activity, NIR‐I emission, good biocompatibility, and high photostability allow Tph‐Dbd to be used for efficient in vitro fluorescence imaging guided PDT. Moreover, the impressive photothermal effect of Tph‐Dbd can overcome the limitations of PDT in the treatment of hypoxic tumors. This study highlights a strategy for designing NIR‐II excitable two‐photon photosensitizers for advanced PDT.