Highly selective luminescence sensing for the detection of nitrobenzene and Fe3+ by new Cd(ii)-based MOFs

Abstract

Herein, three new luminescent metal–organic frameworks (MOFs), namely {[Cd₄(H₃L)₄(H₂O)₁₂]·2.5H₂O}_n (1), {[Cd(L)]·2.5H₂O·3[H₂N(Me)₂]}_n (2), and {[Cd₂(L)(DMA)]·[H₂N(Me)₂]}_n (3), were designed and successfully prepared via a solvothermal reaction using V-shaped rigid multicarboxylate 2,4-di(3′,5′-dicarboxylphenyl)benzoic acid (H₅L) and Cd(II) salts in various solvent systems. The structural analyses indicated that the H₃L²⁻/L⁵⁻ ligands took three different coordination fashions in 1–3; this resulted in a diversity of targeted MOFs. The solid-state luminescence properties of three MOFs were studied under ultraviolet light irradiation at ambient temperature, and 3 showed a high selectivity and sensitivity for nitrobenzene and Fe³⁺ because of the quenching effect. Thus, it could be a potential crystalline material for detecting these substances. The mechanisms of the quenching effect and sensing properties of 3 have been discussed in detail.