Cage, molecular

Several alternative methods have been considered in order to increase the energy density of natural gas and facilitate its use as a road vehicle fuel. It can be dissolved in organic solvents, contained in a molecular cage (clathrate), and it may be adsorbed in a porous medium. The use of solvents has been tested experimentally but there has been little improvement so far over the methane density obtained by simple compression. Clathrates of methane and water, (methane hydrates) have been widely investigated but seem to offer little advantage over ANG [4]. Theoretical comparison of these storage techniques has been made by Dignam [5]. In practical terms, ANG has shown the most promise so far of these three alternatives to CNG and LNG. 

Phlhalocyanines (Pc s) are probably the first repotted and most studied organic semiconductors [86]. They are thermally stable up to 400 "C, and easy to evaporate under vacuum. The Pc molecule (shown in Fig. 14-17), presents the structure of a molecular cage in which various metals can be introduced. 

Molecular Cages and Clusters of the Heavier Croup 14 Elements... 

An overview of the synthesis, structure, photophysical properties, and applications of squaraine rotaxanes as fluorescent imaging probes and chemosensors is provided in a recent review [67]. Although a variety of squaraine dyes form rotaxanes with the molecular cage 25 or with a tetralactam macrocyclic system introduced by Leigh and co-workers [16, 17], there is no evidence in the literature that conventional cyanine dyes can be embedded in these macrocycles. 

MO LCAO methods, 34 136 Molecular-beam surface scattering, 26 26, 27 Molecular Cage, 34 226 Molecular design in cyclodextrin, 32 427 Molecular dynamics diffusion in zeolites, 42 2, 4-6 argon, 42 20... 

The DegP Protease Chaperone A Molecular Cage with Bouncers 275... 

Compared to small two-dimensional molecules, for example the planar benzene, the structures of these three-dimensional systems are aesthetically appealing. The beauty and the unprecedented spherical architecture of these molecular cages immediately attracted the attention of many scientists. Indeed, Buckminsterfullerene CgQ rapidly became one of the most intensively investigated molecules. For synthetic chemists the challenge arose to synthesize exohedrally modified derivatives, in which the properties of fullerenes can be combined with those of other classes of materials. The following initial questions concerned the derivatiza-tion of fullerenes What kind of reactivity do the fullerenes have Do they behave like a three-dimensional superbenzene What are the structures of exohedral fullerene derivatives and how stable are they ... 

The oxidation of various alcohols by the poly(e-carbobenzoxy-L-lysine)-Cu complex was studied by Welch et aL127. The polymer catalyst showed selectivity in oxidation by virtually excluding alcohols of bulky structure such as diisopropyl and diisobutyl carbinol while admitting simple alcohols arch as n-butyl, iso-butyl, and sec-butyl. It was suggested from structural studies that the selectivity of the polymer catalyst resulted from the highly complex geometry of the molecular cage formed by the helix and the amino acid side chain around the coordinated Cu. The... 

VIGNETTE 1.9 SIZE EXCLUSION IN HETEROGENEOUS CATALYSIS AND SEPARATION PROCESSES Zeolites—Molecular Cages for Selectivity in Separation and Catalysis... 

The sesquisiloxanes, (RSiOi,s)n (n = 4, 6, 8, 10, 12), adopt a variety of molecular cage structures (Figure 13).404-408 The ferr-butylgermanium sesquioxide, (Bu Ge Og, has the same structure as its silicon analogue.409... 

The crystal structures of several silver thiolates have now been reported and, in general, the Ag—S distances were between 240 and 280 pm.299-302 If longer distances (e.g. 330 pm) or secondary bonding were included in the interpretation, then molecular cycles and a variety of molecular cages could be recognized. These included [Ag4(SR)6]2-, [Ag5(SR)6], ... 

Accordingly, cluster formation reactions can be (a) (I) - (II) with L/M increase (usually by ligand addition) or (b) (III) -+ (II) with L/M decrease (by ligand removal or metal addition). The Zn2+/ SPh and Cu+/ SPh systems exemplify both directions of formation of molecular cages ... 

Heterotopic Coreceptors — Cyclophane Receptors, Amphiphilic Receptors, Large Molecular Cages... 

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