Journal of East China Normal University(Natural Science) ›› 2023, Vol. 2023 ›› Issue (1): 73-81.doi: 10.3969/j.issn.1000-5641.2023.01.008

• Functional Materials • Previous Articles     Next Articles

N-alkylation modification of metal-organic frameworks to afford responsive fluorescence

Xiaoyan LIU, Enqing GAO*()   

  1. Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, China
  • Received:2022-07-26 Accepted:2022-10-20 Online:2023-01-25 Published:2023-01-07
  • Contact: Enqing GAO


In this study, the electron-deficient pyridinium group and the naphthalene fluorophore were simultaneously introduced to a bipyridyl-containing Zr(Ⅳ) metal-organic framework (MOF) by the N-alkylation post-synthetic modification. The obtained ionic MOF, Zr-bpy-MNap, is nonluminous in the pristine state but shows selective fluorescence turn-on responses to some solvents and ammonia. Test papers were prepared using the MOF for the identification of solvents and detection of ammonia in air. The fluorescence turn-on response is considered to be due to complex host-guest interactions and solvation effects. The MOF is non-fluorescent due to the quenching effects of the host-guest communications between the bromide ion and the framework. On exposure to some solvents or ammonia, the quenching mechanisms are weakened or destroyed by the solvation of bromide or host-guest interactions between ammonia and the framework, resulting in fluorescence turn-on responses. The fluorescence originates from the charge-transfer transition between the naphthyl group and the electron-deficient framework.

Key words: metal-organic frameworks, post-synthetic modification, fluorescence sensor, ammonia

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