Two Cu(II) double betaine coordination polymers with different metal-organic frameworks

Two new Cu(II) coordination polymers with double betaine ligands have been prepared, and their structures have been characterized by single-crystal X-ray diffraction techniques. The structure of [Cu(L-1)(2)](Clo(4))(2)center dot 2H(2)O 1 (L-1 = 1,3-bis(pyridinio-4-carboxylato)-propane) contains 1-D cationic chains, in which the adjacent Cu(II) atoms are doubly bridged by L-1 ligands in the syn-syn bis-monodentate mode. In [Cu(L-2)(2)](Clo(4))(2)center dot 4H(2)O 2 (L-2 = 1,4-bis(pyridinio-4-carboxylato)-1,4-dimenthyl benzene), the Cu(II) atoms are joined by the L-2 ligands in the same coordination mode as 1 in two directions to form a 2-D grid-like framework. The crystal packing in 1 and 2 is controlled mainly by face-to-face pi-pi stacking interactions between pyridine rings. The thermal stability of 1 has also been investigated. (c) 2006 Elsevier B.V. All rights reserved.