Structural diversity and properties of six coordination polymers derived from 1,2/1,3-phenylenedioxydiacetic acids and varied N-donor co-ligands

Based on two positional isomers of phenylenedioxydiacetate ligands and different N-containing co-ligands, six novel coordination polymers, formulated as {[Zn(o-PDOA)(bpp)]·2H2O}n (1), {[Cd(o-PDOA)(bix)]·3H2O}n (2), [Cd(m-PDOA)(bix)]n (3), [Cd(m-PDOA)(bib)]n (4), [Zn(m-PDOA)(bix)]n (5), {[Zn(m-PDOA)(bib)]·2H2O}n (6), (o/m-H2PDOA = 1,2/1,3-phenylenedioxydiacetic acid; bix = 1,4-bis(imidazol-ylmethyl)benzene; bib = 1,4-bis(1H-imidazol-1-yl)-butane; bpp = 1,3-bis(4-pyridyl)propane), have been synthesized under hydrothermal conditions. Compound 1 features a three-dimensional (3D) 2-fold interpenetrating cds topology. In 2, the (H2O)6 clusters interlink the 1D double [Cd2(o-PDOA)2(bix)2]n chains into a 3D supramolecular network. Compound 3 is a (3,5)-connected 2D layer with (42.6)(42.67.8) topology. Compound 4 exhibits a 3-fold interpenetrating pcu topological network, while, 5 is a 2D puckered meso-helical 44-sql layer built by alternately arranged right-handed and left-handed helical chains. In contrast to 1–5, compound 6 possesses a 1D loop-like chain and, interestingly, rare D4 tetrameric (H2O)4 cluster extends the chains into a 3D supramolecular framework. Moreover, the thermal stabilities and luminescent properties of compounds 1–6 have also been investigated.