Three new solvent-directed Cd(II)-based MOFs with unique luminescent properties and highly selective sensors for Cu2+ cations and nitrobenzene

Three new solvent-induced metal-organic frameworks (MOFs)-[Cd(H2L)(H2O)(3)]center dot NMP (1), [Cd-3(L)-(H2O)(4)(OH)(2)] (2) and [Cd(L)(0.5)(H2O)]center dot H2O (3)-were designed and successfully prepared via solvothermal reaction by multidentate phenyltetracarboxylic acid [1,1': 4', 1 ''-terphenyl]-2', 3,3 '', 5'-tetracarboxylic acid (H4L) and Cd(II) salts in various solvent systems. Structural analyses indicated that the H2L/L ligands took three different coordination fashions in 1-3, and thus resulted in diversity of the targeted MOFs. Solidstate luminescent properties of the three MOFs were studied under ultraviolet light irradiation at ambient temperature; 3 in particular showed high selectivity and sensitivity for Cu2+ ions and nitrobenzene because of the quenching effect, which thus could make it a potential crystalline material for detecting these substances. The mechanisms of the quenching effect and sensing properties of 3 are discussed in detail.