Diamondoid geometry

Fig. 37) The other side of the cluster contained a p -hydroxyl group to charge balance. Because the copper clusters were in a pseudo-tetrahedral geometry, coupled with the tetrahedral ligand, the framework did have diamondoid geometry. Structure 26 was also twofold interpenetrated to fill some of the void space generated (Fig. 38). 

Since diamondoids possess the capability for derivatization, they can be used to achieve suitable molecular geometries needed for MBBs of nanotechnology. Functionalization by different groups can produce appropriate reactants for desired reactions, microelectronics, and optics, by employing polymers, films, and crystal engineering. 

The phase transition boundaries (phase envelope) of adamantane need to be investigated and constmcted. Predictable and diverse geometries are important features for molecular self-assembly and pharmacophore-based dmg design. Incorporation of higher diamondoids in solid-state systems and polymers should provide high-temperature stability, a property already found in polymers synthesized from lower diamondoids. 

In the analysis of the topology of such nets we can look for a classification scheme that will allow one to uniquely assign equal nets (up to isomorphism) derived from totally different crystal structures. Remember that the topology is not influenced by the metrical properties of the structure (angles, distances), so that a 4-connected diamondoid net is such, even if highly distorted (the geometry around the nodes could be far from tetrahedral), and also, obviously, is not dependent on the chemical nature of each node/vertex. 

The compound oo[K2PdSeio] [126] provides an intriguing extra facet of this supramolecular chemistry. There are two interpenetrating but different diamondoid lattices, one with [Pd(Se4)4/2] units and the other with [Pd(Se6)4/2p units. The local coordination at Pd is square planar, even though the Pd atoms are located at the tetrahedral connection sites of the diamondoid lattice. The conversion between tetrahedral and square planar geometries is achieved by means of the flexible Se, chains. Note the discussion in Section 8 about the cation influences on the crystallization of palladium polyselenide compounds. 

Fig. 1 Class I supramolecular isomers of [Ag(4-CNpy)2]BF4l in which the flexible Ag(I) coordination geometry leads to three-dimensional diamondoid (a) or two-dimensional (4.4) grid structures.

Ag—N(cn) contacts can only be considered as weak interactions. Polymeric propagation via the bridging ligands in this isomer results in a two-dimensional sheet structure of (4,4) topology (Fig. lb), in contrast to the three-dimensional diamondoid assay observed in the first isomer. The difference in polymeric dimensionality of the two compounds, i.e., two- versus three-dimensional, is therefore a direct result of the different geometries adopted at the Ag(I) cation, square-planar versus tetrahedral. 

Another interesting case in crystal engineering is the one of interpenetrated cyano-bridged diamondoid networks. Zinc(II) easily adopts a tetrahedral geometry, so the solid-state structure of Zn(CN)2 is quite predictable tetrahedral zinc ions are connected by cyano groups generating a diamond-like net, with double interpenetration (Schemel). The cadmium derivative. 

Diamondoids possess great capability for derivatization. This matter is of importance in reaching suitable molecular geometries needed for molecular building blocks of nanotechnology. These molecules are substantially hydrophobic and their solubility in organic solvents is a function of that (adamantane solubility... 

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