Construction of coordination polymers by different conformational flexible pyridyl-type ligands and copper (II) ions

The reaction of the flexible ligand 1,2-bis(4-pyridinecarboxamido)ethane (L) with copper (II) perchlorate under the same conditions lead to the formation of two coordination polymers with different network structures: {[Cu(L)(2)(H2O)] (.) (ClO4)(2) (.) (H2O)(6)}(infinity) (1), {[Cu(L)(2)(ClO4)] (.) (ClO4)}(infinity) (2). L exhibits different conformations in 1 and 2. The copper (II) centers in 1 are bridged by two gauche-ligands to give a cyclic closed structure which extend to form 1-D chain, and the adjacent (CuCu)-Cu-... separation is 12.73 Angstrom. Such chains form a layer structure, which furthermore condenses into a 3-D structure through hydrogen bonds. In 2, the copper (II) centers are bridged by anti-ligands to form rhombus-like grids, and the adjacent (CuCu)-Cu-... separation is more than 22.00 Angstrom. These rhombus-like grids form threefold interpenetrating nets. Water molecules or perchlorate anions fill the channels in 1 and 2. (C) 2003 Published by Elsevier Ltd.