Syntheses, Structures and Properties of Ni(II)/Cd(II)/Zn(II) Complexes with Flexible Homophthalic Acid and Diimidazolyl-Type Ligands

Based on flexible homophthalic acid (H(2)hmph) and diimidazolyl-type bonds, three novel coordination polymers with the formulas determined as {[Ni-2(hmph)(2)(bib)(2)(H2O)(2)]center dot 3H(2)O}(n) (1), [Cd(hmph)(bib)](n) (2) and {[Zn(hmph)(bip)]center dot H2O}(n) (3) (bib =1,4-bis(1-imidazolyl)benzene; bip=3,5-bis(1-imidazolyl)pyridine) have been solvothermally synthesized. Complex 1 displays a 2D mono-layer structure featuring Ni-carboxylate chains cross-linked further by bib co-ligands. Complex 2 exhibits a 2D bilayer structure containing double-stranded Cd-carboxylate chains bridged by bib co-ligands, wherein there are carboxyl-bridged dinuclear kernels. Complex 3 is double-stranded chain featuring Zn-carboxylate binuclear units extended further by bip co-ligands. TGA experiments show that all three complexes have high thermal stabilities. And the magetic data indicate there is typical ferromagnetic exchange coupling in complex 1. Furthermore, the fluorescent properties of both complexes 2 and 3 show significant blue-shift compared with the free ligands. CCDC: 1935595, 1; 1935596, 2; 1935599, 3.