Borromean sheets assembled by self-supporting argentophilic interactions

An infinite two-dimensional Borromean coordination framework, stabilized by argentophilic interactions, was obtained by the reaction of a flexible ligand with AgBF4. © The Royal Society of Chemistry 2005.</p

Influence of the metal-to-ligand ratio on the formation of metal organic complexes

Three copper(II) salts with a chloride, bromide or nitrate counterions in combination with the ditopic ligand 1,3-bis(imidazol-1-ylmethyl)benzene (L) were used to study the influence of the metal to ligand molar ratio on the formation of the final product. Single-crystal X-ray analysis revealed structural diversity of the products formed, ranging from discrete species to extended 1D and 2D coordination polymers. Similar types of 1D chains were formed for all counterions. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.</p

The solvent-templating effect as the driving factor that influences the formation of crystalline materials based on the stacking of metallocycles

A series of recrystallisations of a 1 : 1 CuCl2 : L (L = 1,4-bis[(2-methylimidazol-1-yl)methyl]benzene) mixture from a variety of common solvents has been undertaken in order to investigate the effect of solvent templation on the resulting crystal forms. Single crystal X-ray diffraction analysis of eight new solvates of [CuCl2L]n reveals the solvent dependent formation of either a discrete dinuclear metallocycle or a one-dimensional coordination polymer. Conformational flexibility of both the ligand and the metal-ligand bonds results in the ability of these compounds to form a variety of structures. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.</p

Permeability of a seemingly nonporous crystal formed by a discrete metallocyclic complex

We describe the structure and permeability of a crystalline material that appears to be nonporous in a conventional sense. The material is initially formed as a solvate, and removal of the solvent molecules under relatively mild conditions proceeds via a single-crystal to single-crystal transformation, leaving the host structure intact. Although discrete unoccupied voids of 108 Å3 are present in the structure, it is not possible to map open channels that represent an intuitive pathway for guest diffusion. Despite the apparent absence of pores, the material is permeable to a variety of gases including H2, O2, N2, CO, CH4, CO2, and I2. These findings show that porosity in crystalline systems cannot always be rationalized by considering the static structures and that as-yet unknown dynamic and cooperative mechanisms prevail by which porosity can be induced. Copyright © 2006 American Chemical Society.</p

A discrete metallocyclic complex that retains its solvent-templated channel structure on guest removal to yield a porous, gas sorbing material

A discrete rectangular metal-organic complex that stacks to form one-dimensional channels filled with acetonitrile solvent molecules is described. Removal of the solvent under relatively mild conditions proceeds via a single-crystal to single-crystal transformation that leaves the host lattice unaltered. These findings proffer a design strategy for porous materials based on the simple principle that rigid molecular rings cannot pack efficiently and would thus favor the inclusion of guest species whenever possible. Upon guest removal, an efficiently packed new phase can then only be achieved by means of bond cleavage. Thus, achieving crystal porosity by maintaining robust metal-ligand coordination bonds in such discrete cyclic systems directly parallels the strategy employed for MOFs. Copyright © 2005 American Chemical Society.</p

Guest-induced conformational switching in a single crystal

Without destruction of monocrystallinity: The conformational switching of a dinuclear metal complex between four distinct states (see picture) occurs without destroying the single crystal. This observation implies a substantial degree of cooperativity between host molecules during guest uptake, release, or exchange. (Figure Presented). © 2006 Wiley-VCH Verlag GmbH & Co. KGaA.</p

Acetylene absorption and binding in a nonporous crystal lattice

Unusual storage: An organic nonporous material, p-tert-butylcalix[4]arene, sorbs acetylene with high storage density under ambient conditions. It is presumed that gas molecules diffuse through the seemingly nonporous lattice without disrupting the arrangement of the host molecules (see picture; red O, blue C, gray H, yellow void space). (Figure Presented) © 2006 Wiley-VCH Verlag GmbH & Co. KGaA.</p

Construction of one- and two-dimensional coordination polymers using ditopic imidazole ligands

A series of ditopic imidazole functionalised ligands have been investigated for their propensity to form one- and two-dimensional coordination polymers with a range of metals. We show that ditopic imidazole ligands have the versatility to be exploited in the formation of a variety of coordination polymers. © 2006 Elsevier B.V. All rights reserved.</p