ORIGINAL PAPER Histamine Molecule and Dianion Oxalate are Efficient Blocks for Building 2D Supramolecular Networks Adriana Herna ´ndez Calva • Ana Lilia Padilla Velasco • A ´ ngel Mendoza Martı ´nez • Aaro ´n Pe ´rez-Benı ´tez • Sylvain Berne `s • Enrique Gonza ´lez Vergara Received: 6 October 2010 / Accepted: 30 April 2011 / Published online: 15 May 2011 Ó Springer Science+Business Media, LLC 2011 Abstract One salt and two Cu(II) complexes (H 2 hsm) (ox), 1, [Cu(hsm)(ox)], 2, and [Cu(hsm)(ox)H 2 O], 3, have been synthesized and X-ray characterized (hsm is hista- mine and ox 2- is the oxalate dianion). Starting from the prochiral tetracoordinated complex 2, pentacoordinated complex 3 crystallizes as a racemic mixture of the enan- tiomeric D and K isomers, in space group P2 1 /c. In all cases, the side chain of the hsm group is gauche, allowing the formation of strong hydrogen bonds in the salt 1, and to chelate the metal center in complexes 2 and 3. The com- bination hsm/ox seems to favor the formation of 2D supramolecular structures (planes or wavy planes), through efficient networks of N–HÁÁÁO hydrogen bonds. Cell parameters: 1, P2 1 /c, a = 6.260 (2) A ˚ , b = 11.500 (4) A ˚ , c = 12.525 (4) A ˚ , b = 104.047 (17)8; 2, C2/c, a = 10.7966 (13) A ˚ , b = 15.5622 (16) A ˚ , c = 11.3996 (15) A ˚ , b = 106.261 (11)8; 3, P2 1 /c, a = 7.0627 (6) A ˚ , b = 7.1323 (6) A ˚ , c = 20.0296 (19) A ˚ , b = 91.529 (7)8. Keywords Oxalate Á Histamine Á Networks Á Crystal structure Á Hydrogen bonds Á Helicity Introduction It is well known that small molecules or ions are suitable synthons for crystal engineering. Stable supramolecular structures are however currently far to be predictable, and the study of molecular tectonics [1] is still considered as an immature science. For instance, well established and robust rules for building supramolecular architectures based on hydrogen-bonded networks are limited to a few functional groups [2]. For this reason, any report about a systematic behavior for a given synthon is of interest, since knowledge may be transferred to other structurally related synthons. The present work deals with the use of the oxalate dianion (C 2 O 4 2- , ox 2- ) which may be considered as a quasi 0D (discrete) node for supramolecular chemistry. We explore its bonding ability in an organic salt as well as in coordi- nation complexes. The spacer used for such a purpose is histamine or histaminium dication (hsm and H 2 hsm 2? , respectively). The crystallography associated to H 2 hsm 2? may have some relevance in biochemistry, since in the vicinity of some biomembranes, the predominant form of histamine is dication [3]. Experimental Synthesis of Histaminium Oxalate (H 2 hsm)(ox), 1 All regents were analytical grade (Sigma Chemical Co.) and were used without further purification. Compound 1 was obtained as follows: in a 50 mL round bottom flask, 2 mmoles of histamine (hsm 0.376 g) were placed together with 25 mL of methanol. The mixture was stirred until hsm dissolved. Then 2 mmoles (0.247 g) of 4-dimethylaminopyridine (DMAP) were added and the A. H. Calva Á A ´ . M. Martı ´nez Á E. G. Vergara Centro de Quı ´mica-ICUAP, Beneme ´rita Universidad Auto ´noma de Puebla, Puebla, Pue, Mexico A. L. P. Velasco Á A. Pe ´rez-Benı ´tez Facultad de Ciencias Quı ´micas, Beneme ´rita Universidad Auto ´noma de Puebla, Puebla, Pue, Mexico S. Berne `s (&) DEP, Facultad de Ciencias Quı ´micas, Universidad Auto ´noma de Nuevo Leo ´n, Guerrero y Progreso s/n, Col. Trevin ˜o, 64570 Monterrey, NL, Mexico e-mail: sylvain_bernes@hotmail.com 123 J Chem Crystallogr (2011) 41:1461–1466 DOI 10.1007/s10870-011-0122-7