1. Introduction Crystal engineering and rational design of metal- containing supramolecular systems, including hydrogen bonds, π-π stacking, or by other intermolecular interactions, keep record of rapid developing in recent time [1-4]. Interesting metal-containing supramolecular systems consist of coordination or organometallic complexes connected by strong hydrogen bond motifs, including type of interactions: O–H∙∙∙O, N–H∙∙∙O, N–H∙∙∙N and O–H∙∙∙N [5-9]. The construction of hydrogen-bonded coordination networks is achieved by employing organic ligands with H-bonding functionalities of e.g. –NH 2 , –OH, –CO 2 H, –CONHR and –CONH 2 combined with coordination sites of transition metals [2-6]. One of the most potential ligands for construction hydrogen- bonded networks is 4-pyridylmethanol (4-PM). Only few complexes with 4-pyridylmethanol have been studied by X-ray so far. 4-pyridylmethanol in these complexes exists as a terminal ligand, thus complex molecules contain terminal O–H functionality, which are connected by O–H…O hydrogen bonds [10-16] into supramolecular structure. Only one complex is known, where 4-pyridylmethanol is N,O-bridging ligand [17] so far. In comparison 4-pyridylmethanol as a ligand with related 3-pyridylmethanol, 3-pyridylmethanol is usually N,O-bridging ligand and it is complexes are coordination polymers resulting 1-D chains [18-23] or 2-D sheets [18,19,24-28]. In only few complexes, 3-pyridylmethanol appears as a terminal N-donor ligand which is additionally connected by some O–H…O hydrogen bonds [18,29-33]. In this paper, we present our results of structural and spectral investigation of two copper(II) carboxylate complexes with 4-pyridylmethanol [Cu(nif) 2 (4- PM) 2 ]•CH 3 OH, (nif = niflumate (2-{[3-(trifluoromethyl) Central European Journal of Chemistry * E-mail: jan.moncol@stuba.sk 1 Department of Inorganic Chemistry, Slovak University of Technology, SK-81237 Bratislava, Slovakia 2 Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, CZ-53210 Pardubice, Czech Republic 3 Department of Chemistry, University of Jyväskylä, P.O. Box 35, FI-40014 Jyväskylä, Finland 4 Faculty of Chemistry, University of Wroclaw, 50383 Wroclaw, Poland Jaroslava Maroszová 1 , Jan Moncol *1 , Zdeňka Padělková 2 , Reijo Sillanpää 3 , Tadeusz Lis 4 , Marian Koman 1 Self-assembled hydrogen-bonded coordination networks in two copper(II) carboxylates with 4-pyridylmethanol Research Article Abstract: © Versita Sp. z o.o. Received 14 November 2010; Accepted 6 February 2011 Keywords: Copper complexes • Carboxylates • Supramolecular chemistry • Hydrogen bonds • Crystal structure The crystal and molecular structure of [Cu(nif) 2 (4-PM) 2 ]•CH 3 OH (1) and [Cu(2-Clbz) 2 (4-PM) 2 (H 2 O)] (2), (where nif = niflumate anion, 2-Clbz = 2-chlorobenzoate anion and 4-PM is the 4-pyridylmethanol), have been determinated by X-ray crystallography. The Cu 2+ cation in (1), is coordinated by two pairs of oxygen atoms from asymmetric bidentate niflumate anions and by a pair of pyridine nitrogen atoms from monodentate 4-pyridylmethanol ligands in trans position forming an extremely elongated bipyramid. The Cu 2+ cation in (2), is coordinated by a pair of oxygen atoms from monodentate 2-chlorobenzoate anions, further by a pair of pyridine nitrogen atoms from monodentate 4-pyridylmethanol ligands and finally by a water oxygen atom forming a tetragonal-pyramidal coordination polyhedron. The molecules of both complexes in crystal structures are linked by O–H···O hydrogen bonds, which created a three- dimensional hydrogen-bonding networks. The π-π stacking interactions are also observed in crystal structures of complex 2. The spectral properties (IR and electronic spectra) of both complexes were also investigated. Cent. Eur. J. Chem. • 9(3) • 2011 • 453-459 DOI: 10.2478/s11532-011-0023-9 453