Four coordination polymers constructed from a multicarboxylate ligand and metal centers various from Ba2+, Cu2+, Zn2+ to Gd3+: Syntheses, crystal structures and properties

Hydrothermal reactions between H4ODPA (2,2′,3,3′-oxydiphthalic acid) and metal ion salts of Ba2+, Cu2+, Zn2+ and Gd3+ afford four novel coordination polymers [Ba(H2ODPA)(H2O)4] · H2O (1), [Cu2(ODPA)(H2O)3] · H2O (2), Zn2(ODPA)(H2O)2 (3) and [Gd(HODPA)(H2O)3.5] · H2O (4), accordingly. These polymers show great differences in regard to their structures and properties originated from the variation of size and coordination geometry of the metal ions. Compound 1 presents puckered achiral layer structure with (4.82) topology with helices, 2 has a 63 topology with copper tetramer as SBUs, 3 has chiral layer with two kinds of helices built up from Zn-binuclear “paddle-wheel” like SBUs, and 4 features a simple 1D helix with opposite chirality. Compound 3 shows obvious fluorescent emissions upon excitation. Compound 2 shows ferromagnetic interactions between CuII centers bridged by carboxylate groups, whereas compound 4 presents weak ferromagnetic interaction between GdIII ions.