A supramolecular copper(II) compound with double bridging water ligands: synthesis, crystal structure, spectroscopy, thermal analysis, and magnetism

A complex of composition {[{Cu(NDC)(OH2)(tn)(mu-OH2)}(2)]center dot 2H(2)O}(a) (1) and a mononuclear complex salt [Cu(OH2)(2)(tn)(2)](NDC)center dot 3H(2)O (2), where NDC = 2,6-naphthalenedicarboxylate dianion and tn = 1,3-diaminopropane, were simultaneously crystallized from an aqueous solution of the copper(II) naphthalenedicarboxylate-1,3-diaminopropane-methanol system. The crystal and molecular structures of both complexes were determined by single-crystal X-ray diffraction. Compound (1) consists of a supramolecular coordination complex in which the monomeric unit is assembled from a homodinuclear Cu(II) bridged by two water ligands. The Cu(II) centers exhibit distorted octahedral coordination; the equatorial plane is provided by one chelating tn ligand, one NDC2- ligand, one mu-H2O while the axial positions are occupied by H2O and mu-H2O. Strong intra- and/or intermolecular hydrogen bonds, also involving the crystallization water molecules, together with pi-pi stacking interactions, are involved in building up the supramolecule. The solid structure of compound (2) includes three water molecules of crystallization, the counter ion NDC2-, and a Cu(II) cationic complex in which the metal is six-coordinated in an axially elongated octahedron defined by two chelating tn ligands in the equatorial plane and two water ligands in the axial positions. Thermal analyses of (1) show two significant weight losses corresponding to water molecules (lattice and coordinated), followed by the decomposition of the network

Spontaneous Assembly Of A Hinged Coordination Network

THE field of supramolecular chemistry has advanced to a stage at which it is possible to select building blocks that will self-assemble into structures with specific network topologies(1-3). This makes possible the rational design and synthesis of molecular solids with potentially interesting properties. Here we report the construction of open, hinged networks from molecular building blocks, This class of materials has been predicted to exhibit unusual mechanical properties, including auxetic behaviour (negative Poisson's ratio) and negative coefficients of thermal expansion(4-6). Our approach relies on the notion that rigid organic molecules of high symmetry will adopt one of only a few possible structures when linked via hydrogen bonds or coordination to metals(7-9). We use trigonal ligands to make networks joined at the vertices by metal ions; the resulting networks are homeotypic(10) with the honeycomb-like AIB(2) and the hinge-like ThSi2 phases. The hinge-like network has channels of inner diameter 15 Angstrom, within which included molecules can be exchanged while the framework remains intact, We have not yet determined whether this material is auxetic.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62644/1/374792a0.pd