J. Pasán

Extending the halogen-bonded supramolecular synthon concept to 1,3,4-oxadiazole derivatives

A series of five crystal structures of 1:1 halogen-bonded complexes were obtained from 4-[5-(4-alkoxyphenyl)-1,3,4-oxadiazole-2-yl]pyridine and 1,3,5-trifluorotriiodobenzene. Electronic structure calculations show that the N(oxadiazole)⋯I interaction in the new synthon is as strong as the classic N(pyridine)⋯I interaction. Oxygen to sulfur atom subsitution on the oxadiazole ring results in a different supramolecular packing where the N(pyridine)⋯I interaction is favored, which could be rationalized by the changes in the molecular electrostatic potential predicted from the theoretical calculations.

Recognition of self-assembled water-nitrate cluster in a Co(III)-2,2′-bipyridine host: Synthesis, X-ray structure, DNA cleavage, molecular docking and anticancer activity

AbstractA mononuclear cobalt(III) complex [Co(bpy)2Cl2]NO3⋅2H2O (1) (bpy = 2,2′-bipyridine) has been synthesized and crystallographically characterized. Self-assembly of the lattice water molecules from rectangular tetrameric water cluster interacts with nitrate anion along the c-axis forming a six membered hexagonal water-nitrate cluster. It presents a new mode of association of water molecules with nitrate molecules which is not predicted theoretically or found experimentally. The molecule effectively cleaves bacterial genomic DNA and shows important cytotoxicity against human hepatocarcinoma cell (HepG2). Graphical AbstractThis paper reports an X-ray crystallographic characterization of a Co(III)-bpy complex which also presents a new mode of association of water molecules with nitrate molecules which was not predicted theoretically or found experimentally or reported in literature. The molecule effectively cleaves bacterial genomic DNA and shows important cytotoxicity against human hepatocarcinoma cell (HepG2).

Cadmium(II) coordination polymers based on substituted malonic acid: synthesis, characterization and photoluminescence properties

Four novel complexes of cadmium(II) with alkyl/aryl-substituted malonate ligands of formulae {[Cd(Memal)(H2O)]6·0.5H2O}n (1), [Cd(Etmal)(H2O)]n (2), [Cd(Butmal)(H2O)]n (3) and [Cd(Bzmal)(H2O)]n (4), (Memal = methylmalonate, Etmal = ethylmalonate, Butmal = butylmalonate and Bzmal = benzylmalonate) have been prepared and characterized by single crystal X-ray analysis. Their luminescence, UV-Vis absorption properties and thermal behaviour were also investigated. Complex 1 is a three-dimensional compound where each metal centre is connected to four other ones leading to a sodalite network with the point symbol {42·64}. Each cadmium(II) ion in 1 is seven-coordinate with a water molecule and six oxygen atoms from three Memal ligands building a somewhat distorted pentagonal bipyramidal surrounding. The Memal ligand in 1 adopts a μ3–κO:κ2O′:κ2O′′:κO′′′ coordination mode. 2–4 are isomorphous compounds with a two-dimensional structure where centrosymmetric double oxo(carboxylate-substituted malonate)-bridged dicadmium(II) units are linked to four other dinuclear entities through anti–anti and anti–syn carboxylate bridges to form a Shubnikov tetragonal layered [4462]-sql net. Each cadmium(II) ion in 2–4 is six-coordinate in a distorted octahedral environment with four carboxylate-oxygen atoms building the basal plane and a water molecule plus another carboxylate-oxygen atom in the axial positions. The substituted malonate ligands in 2–4 exhibit the μ4–κO:κ2O′:κ2O′′:κO′′′ coordination mode. The tests of the emission spectra of 1–4 show that the length of the side chain influences the photoluminescence properties of the complexes. Finally, the decays of the luminescence of 1–4 and the respective free substituted malonic acids reveal that the same value of the average life time is observed for 1 (H2Memal), whereas in the case of 2–4, they are greater than that of 1 and those of their corresponding acids. The longer decay rates in 2–4 are consistent with the lack of water molecules in the environment of the cadmium(II) ion in these complexes, indicating that the sheet-like structure of 2–4 provides a chemical surrounding with less non-radiative relaxation processes.

Crystal structure analysis of supramolecular arrangements in bis(1-isoquinolinecarboxamide)alkanes and their Ag(I) complexes

A homologous series of bis(1-isoquinolinecarboxamide)alkane derivatives (3a–f) with two to seven carbon atoms in the alkyl bridge and their Ag(I) complexes (4a–f) have been synthesized. Four ligand and five Ag(I) complex crystal structures were obtained by single crystal X-ray diffraction and analyzed in terms of: a) their structural patterns based on intra- and intermolecular hydrogen bonds which were compared to those of bis(2-quinolinecarboxamide)alkanes (1n) and bis(6-quinolinecarboxamide)alkanes (2n) attending to specific geometrical parameters and b) the Ag(I) coordinate bond effect on these patterns and the amide-to-amide hydrogen bonds. The crystal structures of the ligands 3a, 3c, 3d and 3e synthesized here show amide-to-amide interactions, the same as those occurring in the 2n derivatives, forming one or two-dimensional structures (β-sheets or 4,4-networks) via N–H⋯O(amide) hydrogen bonds. The coordinate bond in the 4n complexes predominates over the amide-to-amide hydrogen bond giving rise to structures ranging from discrete complexes to three-dimensional coordination polymers. Only the 4c complex merges supramolecular β-sheets connected by the silver coordination bonds.

Dynamic behavior in a dryness sensitive 3d-4fmetal–organic framework

Dynamic behavior in a dryness sensitive 3d-4f metal–organic framework Oscar Fabelo,a,b,c Pau Díaz-Gallifa,c Laura Cañadillas-Delgado,a,b,c Jorge Pasán,c Carla Martinez-Benito,c Mariadel Déniz,c Diego Lozano,c Ana Labrador,d Catalina Ruiz-Pérez,c aInstituto de Ciencia de Materiales de Aragón. CSIC-Universidad de Zaragoza. (Spain). bInstitute Laue Langevin. Grenoble (France). cLaboratorio de Rayos X y Materiales Moleculares, Depto. Física Fundamental II, Universidad de La Laguna. Tenerife. (Spain). dBM16 – LLS. European Synchrotron Radiation Facility. Grenoble (France). E-mail: fabelo@ill.fr

Old tools for new materials

24 European Crystallographic Meeting, ECM24, Marrakech, 2007 Page s35 Acta Cryst. (2007). A63, s35 MS13 O1 Old tools for new materials Catalina Ruiz-Pérez, Jorge Pasán, Fernando S. Delgado, Oscar Fabelo, Laura Cañadillas-Delgado, María del Pino Déniz, Eliezer Sepúlveda. Laboratorio de Rayos X y Materiales Moleculares, Dpto. Física Fundamental II, Facultad de Física, Universidad de La Laguna, Tenerife, Spain. E-mail: caruiz@ull.es