Synthesis, crystal structures and luminescent properties of nickel (II) and copper (II) hexaazamacrocyclic compounds with 1,3,5-benzenetricarboxylate ligands

Two new nickel (II) and copper (II) hexaazamacrocyclic compounds {[Ni(L-1)(Hbtc)]center dot 3H(2)O}(n) (1) and [Cu(L-2)(H(2)btc)(2)] (2) (L-1 = 1,3,6,9,11,14-hexaazatricyclo [12.2.1.1(6,9)]octadecane, L-2 = 3,10-bis(2-hydroxyethyl)-1,3,5,8,10,12-hexaazacycltetradecane, and H(3)btc = 1,3,5-benzenetricarboxylic acid), have been synthesized and structurally characterized. In 1 and 2, each metal (II) ion is six-coordinated with four nitrogen atoms from the hexaazamacrocycle and two oxygen atoms from the 1,3,5-benzenetricarboxylate ligands. The Ni (II) ions in the complex 1 are bridged by the Hbtc(2-) anions to form an infinite 1D chain. Hydrogen bonding interactions further link these chains to form a 3D supramolecular architecture. The crystal structure of complex 2 is centrosymmetric and the Cu(II) ion has an axially elongated octahedron geometry. Each [Cu(L-2)(H(2)btc)(2)] unit extends its structure to form a 3D supramolecular structure based on pi-pi stacking and hydrogen bonding interactions. In addition, their luminescent properties have been investigated in the solid state. (C) 2012 Elsevier B.V. All rights reserved.