A versatile luminescent metal–organic framework for selective detection of Fe(iii) cations and Cr(vi) anions

Abstract

Heavy metal ion pollution has become one of the most serious environmental problems, which promotes the continuous exploration of new materials and methods to achieve efficient detection of heavy metal ions. Luminescent metal–organic frameworks (LMOFs) featuring designable, functional structures and tunable luminescence properties exhibit excellent potential for the recognition and detection of heavy metal ions. Herein, a Cd(II)-based luminescence MOF {[Cd₂(2F-bpdc)₂(tib)]}_n (NKM-103) (tib = 1,3,5-tris(1-imidazolyl)benzene; 2F-H₂bpdc = 3,3′-difluorobiphenyl-4,4′-dicarboxylic acid) was successfully designed and synthesized. Owing to the luminescence characteristic of the tib ligand with conjugated units, NKM-103 demonstrates excellent fluorescence emission performance and potential as a sensor for detecting both Fe(III) cations and Cr(VI) anions (Cr₂O₇²⁻ and CrO₄²⁻) through a turn-off effect. Moreover, NKM-103 shows low detection limit and high selectivity for all three types of ions.