Synthesis, crystal structures, photoluminescence, and catalytic reactivity of novel coordination polymers (0-D, 1-D, 2-D to 3-D) constructed from cis-1,2-cyclohexanedicarboxylic acid and various bipyridyl ligands

Six ZnII–(e,a-cis-1,2-chdc) complexes, [Zn2(1,2-chdc)2(2,2′-bpy)2(H2O)2]·H2O 1, [{Zn2(1,2-chdc)2(H2O)2(μ-bpa)}·4H2O]n2, [{Zn2(μ-1,2-chdc)2(μ-4,4′-bpy)}·3CH3OH]n3, [{Zn2(μ-1,2-chdc)2(μ-bpe)}·2H2O]n4, [[{Zn2(μ-1,2-chdc)2}n-(μ-bpp)-{Zn2(μ-1,2-hdc)2(H2O)2}]·CH3CN·2H2O]n5, and [{Zn2(μ-dtp)2(μ-1,2-chdc)}2·4·5H2O]n6 (1,2-chdc = 1,2-cyclohexanedicarboxylate), with different assistant ligands (2,2′-bipyridine (2,2′-bpy), 1,2-bis(4-pyridyl)ethane (bpa), 1,2-bis(4-pyridyl)ethylene (bpe), 1,3-bis(4-pyridyl)propane (bpp), and, 4,4′-bipyridine (4,4′-bpy) and 4,4′-dithiodipyridine (dtp)) have been synthesized and their structures were determined. Depending on the assistant ligands, the structures and dimensionalities of ZnII–(e,a-cis-1,2-chdc) complexes have been varied. Two carboxylates in e,a-cis-1,2-chdc coordinate to ZnII ions with (11) or (10) connectivity. Photoluminescence study of the compounds 1–6 showed that emission spectra of compounds 1, 2, 4, and 5 were observed at 343 nm for 1, 419 nm for 2, 507 nm for 4, 396 nm for 5, respectively, while no obvious luminescences were displayed for 3 and 6. In addition, it has been found that compound 1 catalyzed the transesterification reaction of phenyl acetate with methanol, with quantitative conversion to methyl acetate, under the neutral conditions, while compounds 2–6 showed very slow conversions. The thermal stabilities of these complexes were also examined.