Syntheses, characterizations and properties of five new metal–organic complexes based on flexible ligand 4,4′-(phenylazanediyl)dibenzoic acid

Abstract

Five new metal–organic frameworks have been synthesized under hydrothermal conditions, in CH3CN–H2O, DMF–CH3CH2OH–H2O and DMA–H2O, namely, [ZnL(bimx)0.5]n (1), {[CoL(4,4′-bipy)]·DMF}n (2), {[CdL(4,4′-bipy)]·DMF}n (3), {[ZnL(bibp)]·DMA·(H2O)2}n (4), {[CoL(bpyb)0.5]·(H2O)2}n (5) (bimx = 1,4-bis(imidazol-1-ylmethyl)benzene, 4,4′-biby = 4,4-pyridine, bibp = 4,4′-bis(imidazol-1-yl)biphenyl, bpyb = 1,4-bis(4-pyridyl)benzene, H2L = 4,4′-(phenylazanediyl)dibenzoic acid. These complexes were characterized by elemental analysis, IR spectroscopy, TG and X-ray single-crystal diffraction. In compounds 1, 2 and 3, the bimx, 4,4′-bipy and L2− anions act as bidentate ligands assembling with metal cations to form two-dimensional (2D) sheets. The sheets are stacked in ABAB fashion and accumulate into a 3D framework. Compound 4 possesses a 3D→3D 4-fold interpenetrating architecture with {65·8} topological net, which is similar to the cds topology. Compound 5 also displays a 3D structure with {44·610·8} topology. The photochemical properties were investigated in the solid state at room temperature. The luminescent properties of compounds 1, 3 and 4 are discussed in detail. The UV-vis absorption spectra of compounds 2 and 5 are tested and discussed. In addition, the magnetic properties of compound 5 also are tested and simply analyzed.