D-10 Metal complexes assembled from isomeric benzenedicarboxylates and 3-(2-pyridyl) pyrazole showing 1D chain structures: syntheses, structures and luminescent properties

摘要

Seven new d(10) metal coordination polymers with isomeric benzenedicarboxylates and 3-(2-pyridyl) pyrazole ligands, [Zn2L2(1,2-BDC)(H2O)](n) (1), {[Cd-2(HL)(2)(1,2-BDC)(2)]center dot H2O}(n) (2), [Cd(HL)(1,2- BDC)(H2O)](n) (3), [Zn(HL)(1,3-BDC)(H2O)center dot 3H(2)O](n) (4), [Cd2L2(1,3-BDC)(H2O)](n) (5), [Zn(HL)(2)(1,4-BDC)](n) (6) and [Cd(HL)(2)(1,4-BDC)](n) (7) (BDC = benzenedicarboxylate, HL = 3-(2- pyridyl) pyrazole), have been synthesized and structurally characterized by elemental analysis, IR and X-ray diffraction. Single-crystal X-ray analyses reveal that each complex takes a different one-dimensional (1D) chain structure. In 1-7, the BDCs act as bridging ligands, exhibiting rich coordination modes to link metal ions. The three BDC isomers exhibit different coordination modes: mu(1)-eta(1):eta(1)/mu(3)-eta(2):eta(1), mu(3)-eta(1):eta(2)/mu(3)-eta(2):eta(1), mu(2)-eta(1):eta(1)/mu(1)-eta(1):eta(0) and mu(1)-eta(1):eta(1)/mu(1)-eta(1):eta(0) for 1,2-BDC, mu(1)-eta(1):eta(1)/mu(1)-eta(1):eta(0) and mu(1)-eta(1):eta(0)/mu(2)-eta(2):eta(1) for 1,3-BDC, and mu(1)-eta(1):eta(0)/mu(1)-eta(0):eta(1), mu(1)-eta(1):eta(0)/mu(1)-eta(1):eta(0) and mu(1)-eta(1):eta(1)/mu(1)-eta(1):eta(1) for 1,4-BDC, respectively. In these complexes, HL acts as a simple bidentate chelate ligand (in 2, 3, 4, 6 and 7), similar to 2,2'-bipyridine, or as a tridentate chelate-bridging ligand (in 1 and 5) via deprotonation of the pyrazolyl NH group and coordination of the pyrazolyl N atom to a second metal ion. The structural differences indicate that the backbone of such dicarboxylate ligands plays an important role in governing the structures of such metal-organic coordination architectures, and the chelating bipyridyl-like ligand HL leads to the formation of these coordination polymers with one-dimensional structures by occupying the coordination sites of metal ions. Moreover, the photoluminescent properties of complexes 1-7 were also studied in the solid-state at room temperature.