Three new AIE-cored luminescent Cd-based MOFs with high quantum yields and selective detection of ions in aqueous media

Abstract

Herein, we synthesized three new LMOFs, [Cd(TPPE)_0.5(oba)(H₂O)]_n (LMOF-1), [Cd₂(TPPE)(bpdc)₂]_n (LMOF-2), and [Cd₂(TPPE)(sdc)₂]_n (LMOF-3) (TPPE = 1,1,2,2-tetra[4-(pyridin-4-yl)phenyl]ethylene, oba = 4,4′-diphenyl ether dicarboxylic acid, bpdc = 4,4′-biphenyl dicarboxylic acid, sdc = 4,4′-styrene dicarboxylic acid), with high quantum yields of 43.74%, 36.68% and 45.89%, respectively, exceeding those reported for most Cd-based LMOFs. All three LMOFs have good detection sensitivity for Fe³⁺, CrO₄²⁻ and Cr₂O₇²⁻. Surprisingly, Na⁺ can rarely but significantly enhance the fluorescence intensity of LMOF-3, and the detection limit is 1.90 × 10⁻⁵ M. This is the first reported LMOF material that can quantitatively analyze Na⁺ among references. All results indicate that the three MOFs can be developed into phosphor materials and fluorescent chemical sensors for detecting ions in water.