Two bifunctional photoluminescent Zn (II) coordination polymers for detection of Fe3+ ion and nitrobenzene

Abstract

Two new luminescent metal–organic coordination polymers (MOCPs) of {[Zn6(L)2(H2O)7]·(DMF)2}n (1) and {[Zn(H4L)(bpy)0.5(H2O)2]·H2O}n (2) were solvothermally constructed using zinc salts and ligands (H6L = 5,5′-(propane-2,2-diyl)bis(2-hydroxyisophthalic acid), bpy = 4,4′-bipyridine). The resulted MOCPs were characterized by elemental analysis, powder X-ray diffraction, and single-crystal X-ray diffraction. Single-crystal X-ray study results reveal that compounds 1 and 2 belong to P1¯ and P 21/n space group and show a two- and one-dimensional structure, respectively. Their photoluminescence (PL) properties and thermal properties were also studied. Interestingly, the luminescent responses of compounds 1 and 2 show highly sensitive detection of Fe3+ via an obvious fluorescence quenching. The detection limits of compounds 1 and 2 are 0.25 μM and 0.19 μM toward Fe3+. Compound 2 possesses a ring structure, which is big enough to allow small molecules to easily move into the crystal skeleton and interact with each other. Thus, the luminescence responses of compound 2 were investigated for various organic solvents. These results show that compound 2 has great potential to be developed as the favorable sensor for highly selective detection of nitrobenzene.