Ag+-induced photoluminescence enhancement in lanthanide post-functionalized MOFs and Ag+ sensing.

The robust gallium carboxylate Ga(OH)(btec)·0.5H2O (MIL-61) is selected as a parent MOF to prepare Ln-MIL-61 by PSM. This work investigates the luminescence of Ln-doped MIL-61 (Ln = Eu3+, Tb3+, Sm3+, Dy3+) in the visible light region. Upon 314 nm excitation, the emission spectra of Eu-MIL-61, Tb-MIL-61 and Eu/Tb-MIL-61 all exhibit their respective strong sharp emission bands. However, Sm-MIL-61 and Dy-MIL-61 show very similar emission to MIL-61 and almost no luminescence of Sm3+ and Dy3+. In this work, the weak fluorescence of Sm3+ or Dy3+ doped MIL-61 is effectively sensitized by Ag+. Besides, single-phase white-light emitters based on the resulting 4d-4f heterometallic co-doped MOFs can be realized. Furthermore, Sm-MIL-61 shows more highly sensitive and selective sensing towards Ag+, and is a promising optical sensor for Ag+ detection in a few daily water samples.