Synthesis, structure, fluorescence and photocatalytic properties of two complexes based on a dimethylimidazole biphenyl/isophthalic acid ligand

In this paper, two metal-organic frameworks { [Zn(CIA)(4,4′-BB)]·0·75H2O}n (1) and [Co(CIA)(4,4′-BB)·H2O]n (2) were synthesized by using ligands 5-methoxyisophthalic acid (5-H2CIA) and 4,4′-bis((1H-imidazol-1-yl)methyl)-1,1′-biphenyl (4,4′-BB) under solvothermal conditions. The structures were characterized by TG, IR, PXRD, BET, single-crystal X-ray diffraction and elemental analysis. The results show that 1 and 2 form a three-dimensional structure, where 1 and 2 have good thermal stability. Further study reveals that 1 shows good fluorescence properties and can be used as a fluorescence sensor to detect histidine (His), nitrobenzene (NB), tetracycline (TC) and pyrimethanil (PTH) in water. (LOD: His 0.23 μM, TC 0.17 μM, PTH 0.08 μM, NB 0.03 μM). However, 2 shows better photocatalytic activity and can be used to degrade dyes in water, such as BF (basic fuchsin) and MB (methylene blue). Under visible light irradiation, the degradation rate of BF is 95.5 % and that of MB is 76.1 %. Finally, the mechanism of detection of 1 as a fluorescence probe and the mechanism of photocatalytic degradation of 2 are discussed.