Embedding Multiphoton Active Units within Metal–Organic Frameworks for Turning on High‐Order Multiphoton Excited Fluorescence for Bioimaging

Abstract

AbstractThe fabrication of high‐order multiphoton excited fluorescent materials for second near‐infrared (NIR‐II, 1000–1700 nm) light‐induced fluorescence imaging has always been an intractable challenge. In this study, a reasonable strategy guided by theoretical calculations was employed to fabricate a novel high‐order multiphoton excited fluorescence (H‐MPEF)‐responsive UiO‐type metal–organic framework (MOF, ZrTc). Strategically, the functionalization of the photonic‐responsive thiazolothiazole‐based organic ligand gave rise to amplified H‐MPEF (four‐photon activity) performance and prolonged excitation wavelength (1550 nm) of ZrTcI. The results reveal that the extended π‐electron system, enhanced charge transfer, improved dipole moment, and weakened π‐π stacking interactions within the MOFs endow them with excellent H‐MPEF performance for NIR‐II light‐induced fluorescence imaging. It is an extremely rare report on H‐MPEF bioimaging using MOFs and provide a universal strategy for the fabrication of H‐MPEF‐responsive materials.