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

Herein, three new luminescent metal-organic frameworks (MOFs), namely {[Cd-4(H3L)(4)(H2O)(12)].2.5H(2)O}(n) (1), {[Cd(L)].2.5H(2)O.3[H2N(Me)(2)]}(n) (2), and {[Cd-2(L)(DMA)].[H2N(Me)(2)]}(n) (3), were designed and successfully pre-pared 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.