Crystalline molecular alloys

The dicationic tecton 1-2H(+) leads in the presence of anionic M(CN)(6)(3-) complexes to two almost identical crystalline systems A (M = Fe) and B (M = Co) composed of 2-D H-bonded networks and water molecules. The epitaxial growth of B on A used as seed or A on B generates crystalline molecular alloys.     

Giant core-shell nanospherical clusters composed of 32 Co or 32 Ni atoms held by 6 p-tert-butylthiacalix[4]arene units

Using combinations of p-tert-butylthiacalix[4]arene (TCA) and [M(DMSO)(6)(BF(4))(2)] salts (M = Co(II) or Ni(II)), two almost isostructural core-shell-type thermally stable giant nanoclusters, composed of 32 metal centers, 6 deprotonated calix units binding the metal centers by both their O and S atoms, 24 μ-oxo or μ-hydroxo bridging groups, and 6 MeOH molecules, have been prepared under mild and reproducible conditions. For both giant clusters, the oxidation state II [M(II)(32)O(16)(OH)(8)(CH(3)OH)(6)TCA(6) (M = Co or Ni)] for the metal center was demonstrated by X-ray photoelectron and electronic absorption spectroscopies.     

Charge assisted chiral hybrid H-bonded molecular networks

The co-crystallisation of [Fe(CN)5NO]2- and cyclic achiral 1(2+) and chiral 2(2+) or 3(2+) bisamidinium tectons leads in the crystalline phase to the formation of 1-D H-bonded achiral and chiral molecular networks respectively. In all cases, the network is formed by mutual bridging of the anionic and cationic units through a chelate mode of H-bonding.     

Second sphere supramolecular chirality: racemic hybrid H-bonded 2-D molecular networks

Neutral hybrid 2-D networks have been generated using a bis-amidinium capable of chelating M(CN)6(3-) anions via hydrogen bonds: the packing of the achiral 2-D networks leads to channels which are occupied by water molecules forming polymeric H-bonded chains; furthermore, owing to the dihapto mode of H-bonding, the presence of supramolecular chirality of the delta' and lambda' types taking place within the second coordination sphere of the metallic centre has been demonstrated.     

Molecular tectonics: on the formation of 1-D silver coordination networks by thiacalixarenes bearing nitrile groups

Two new p-tert-butylthiacalix[4]arene derivatives 2 and 3 decorated at the lower rim with four nitrile groups have been prepared and structurally characterised in the crystalline phase. The two ligands, differing by the length of the spacer between the calix moiety and the nitrile group, adopt the 1,3-alternate conformation in the solid state. The ligand 3 bearing four (CH(2))(3)CN fragments behaves as a tecton in the presence of silver salts (AgX, X = BF(4), PF(6) or SbF(6)) and leads to the formation of analogous 1-D linear coordination networks. The tecton 3 acts as a bischelate unit and bridges consecutive silver cations adopting a tetrahedral coordination geometry. Anions and solvent molecules occupy the free space between networks and exhibit no specific interactions with the cationic architecture.     

Design of 3-D coordination networks: topology and metrics

Using 4,4',4"-tricyanotriphenylmethanol 1 as a heterotetradentate tecton with C3v symmetry bearing three CN and one OH group, under self-assembly conditions a 3-D coordination network was obtained in the presence of Ag+ cations acting as a tetrahedral metallic tecton; due to the metrics of 1 (three long and one short distance between the central C atom and N and O coordination sites, respectively), the 3-D network is of pseudo-diamondoid type with different cavity sizes; although a two-fold homo-interpenetration is observed for the 3-D networks, the remaining space is occupied by CHCl3, MeOH solvent molecules and SbF6- anions.     

Molecular tectonics: design of luminescent H-bonded molecular networks

Using bis-amidinium dications as tetra H-bond donor tectons and Au(CN)(2)(-) anion, neutral 1-D networks based on a bis monohapto mode of H-bonding are obtained. Owing to the short metal-metal distance within the network, luminescent crystals are obtained. The emission phenomena may be tuned by the nature of the spacer connecting the two cyclic amidinium groups.     

Molecular tectonics: polymorphism and enhancement of network dimensionality by a combination of primary and secondary hydrogen bond sites

A dicationic tecton bearing four NH and two OH groups, as primary and secondary hydrogen bond donor sites, respectively, leads, in the presence of [M(CN)(4)](2-) anions, to the formation of polymorphic 2- and 3-D hydrogen-bonded networks.