An uncommon 3D 3,3,4,8-c Cd(II) metal-organic framework for highly efficient luminescent sensing and organic dye adsorption: experimental and theoretical insight

摘要

A new Cd(II) based metal-organic framework (MOF), having formula {(CH3)(2)NH2)(6)[Cd-5(L)(4)]center dot H2O center dot 3DMF}(n) (1), has been synthesized based on a rigid tetracarboxylate ligand of terphenyl-3,3 '', 5,5 ''-tetracarboxylic acid (H4L). 1 shows a complicated 3D tetranodal 3,3,4,8-c network with uncoordinated -COO- groups. The highly selective luminescent sensing of 2,4-dinitrophenol (2,4-DNP), 2,4,6-trinitrophenol (TNP) and ferric ions was studied for 1 through the alleviation in its fluorescence intensity. The detection limit of 2,4-DNP was found to be 0.84 ppm, which is 20 times higher than that of 1,3,5-trimethylbenzene, demonstrating greater and selective quenching ability. The possible mechanism associated with the decrease in fluorescence intensity of 1 in the presence of nitroaromatics (NACs) has been addressed by theoretical calculations. Furthermore, 1 displays excellent capacity to adsorb methylene blue (MB) with high selectivity, and it maintains an almost identical adsorption performance after being recycled five times.