Fluorescent molecules confined into the nanopores of metal-organic frameworks generally display alterant luminescence properties, which exhibits broad application prospects. Herein, trans-4-[4-(N,N′-dimethylamino)styryl]pyridine (DMSP) was confined in the nanocavities of UiO-66, and the concomitant fluorescence color change made this host-guest material capable to act as a drug carrier that monitored drug release with luminescence. DMSP radiated green fluorescence with excitation and emission wavelengths at 381 and 478 nm, respectively. While after DMSP was confined in UiO-66, the excitation and emission wavelengths respectively red-shifted to 528 and 579 nm, accompanied by orange fluorescence emission. This luminescence color transformation was confirmed to be associated with the interaction of pyridine N-atom in DMSP with Bronsted acid sites in UiO-66, enhancing the electron push-pull effect of DMSP. This host-guest material remained the biocompatibility, porosity and degradability of UiO-66, and moreover the fluorescence color transformation from orange to green occurred after its decomposition by PO43−. On this basis, this host-guest material was capable to serve as a drug carrier that monitored drug release with the fluorescence signal, which facilitated the visual tracking of drug release in vivo.
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