Two Zn(II) coordination polymers constructed by a new tricarboxylate and different N-containing ligands: synthesis, crystal structures, and selective luminescence sensing for Fe 3+ in aqueous solution

Two Zn(II) coordination polymers, {[Zn3(L)2(bipy)2(H2O)4}n (1) and {[Zn(HL)(4,4′-bibp)}n (2), were obtained from Zn(II) nitrate, a tricarboxylate ligand (H3L) and different N-containing ligands with hydrothermal conditions, where H3L = 4-((6-carboxynaphthalen-2-yl)oxy)phthalic acid, bipy = 4,4′-bipyridine, and 4,4′-bibp = 4,4′-di(1H-imidazol-1-yl)-1,1′-biphenyl. Single-crystal X-ray analysis reveals that 1 has a 2-D layer framework formed by L3− and bipy and 2 has an infinite 1-D structure with Zn2 units built by 4,4′-bibp ligands. The phase purity, IR spectra, thermal stabilities, and fluorescence properties in the solid state of 1 and 2 were investigated. Moreover, 1 and 2 were chosen as fluorescent probes to sense different metal ions, showing selective response to Fe3+ ion through luminescence quenching. The possible sensing mechanism to Fe3+ ion is also discussed.