Hydrothermal synthesis, characterization and crystal structure of a three-dimensional (3D) ZnII supramolecular compound with ethylenediaminetetraacetic acid ligand and 4-(carboxylate)pyridinium guests

A new supramolecular compound [Zn(H2EDTA)(H2O)](Q)2(H2O)2 (1), where H4EDTA ¼ ethylenediaminetetraacetic acid and Q ¼ 4- (carboxylate)pyridinium, has been prepared by mild hydrothermal reaction and characterized by elemental analysis, IR spectrum and thermogravimetric analysis. Single-crystal X-ray diffraction of 1 [monoclinic, space group C2/c, a ¼ 11.310(4) A ° , b ¼ 9.704(4) A ° , c ¼ 23.798(10) A ° , b ¼ 97.401(10)8, Z ¼ 4] revealed that the ZnII ion coordinates to the chelating tetradentate ligand H2EDTA and a water molecule, taking a distorted trigonal-bipyramid geometry. The mononuclear [Zn(H2EDTA)(H2O)] subunits are linked to form two-dimensional layered architectures by the lattice water moieties through O–H· · ·O hydrogen bonds, which are further extended to a three-dimensional (3D) supramolecular network by 4-(carboxylate)pyridinium guests (resulting from the ring-opening hydrolysis of 2,5-bis(4-pyridyl)-1,3,4-oxadiazole) through extensive hydrogen-bonding interactions. The 3D supramolecular framework is also stabilized by significant face-to-face p–p stacking interactions between the aromatic pyridinium systems. q 2004 Elsevier B.V. All rights reserved