Synthesis, spectra and crystal structure of a CuII complex exhibiting novel two-dimensional joint-ladder like hydrogen-bonding pattern with an amino-acid type diazamesocyclic ligand

The mononuclear CuII complex [CuL(H2O)]·2H2O (1) with a diazamesocyclic ligand bearing two functional carboxylic donor groups, 1,5-diazacyclooctane-N,N0-diacetate acid (H2L), has been synthesized and characterized by elemental analyses, thermal analyses and IR spectrum. The crystal structure of 1 has been determined by X-ray diffraction analysis, which revealed that the CuII center coordinates to the tetradentate chelated ligand L and an axial water molecule, and the 1,5-diazacyclooctane (DACO) moiety adopts a boat/chair conformation that inhibits the axial coordination at the metal center to form this penta-coordinated pyramidal (CuN2O3) complex. The most striking feature of this structure is the formation of a novel two-dimensional joint-ladder like architecture through multiple inter- and intramolecular O–H· · ·O hydrogen bonds. The solution behaviors of 1 have been further investigated by conductance, UV–Vis and ESR techniques. q 2004 Elsevier B.V. All rights reserved.