Molecular wheel

A. Muller, E. Diemann, C. Kuhlmann, W. Eimer, C. Serain, T. Tak, A. Knochel, and P. K. Pranzas, Hierarchic patterning, architectures beyond giant molecular wheels , Chem. Commun. 1928-1929(2001). 

This reaction followed the highly fascinating molecular wheel type structure exhibited (260) by [Fe(OMe)2(OOC,CH2Cl)] 0, which was crystallized... 

Cobalt(Il) dicobalt(Ill) tetroxide [1308-06-17, Co O, is a black cubic crystalline material containing about 72% cobalt. It is prepared by oxidation of cobalt metal at temperatures below 900°C or by pyrolysis in air of cobalt salts, usually the nitrate or chloride. The mixed valence oxide is insoluble in water and organic solvents and only partially soluble in mineral acids. Complete solubiUty can be effected by dissolution in acids under reducing conditions. It is used in enamels, semiconductors, and grinding wheels. Both oxides adsorb molecular oxygen at room temperatures. 

Products intermediate to the flexible and rigid foams may be obtained from castor oil (a trihydroxyl molecule), synthetic triols of moderate molecular weight and polyesters with a moderate amount of trifunctional hydroxyl compound in the strueture. Current practice, however, is to use tipped polyols of the type used for flexible foams with MDI. Semi-rigid foams are used for such purposes as crash pads, car steering wheels and packaging equipment. 

Figure 3.3 Molecular structure of G-protein-coupled receptors. In (a) the electron density map of bovine rhodopsin is shown as obtained by cryoelectron microscopy of two-dimensional arrays of receptors embedded in lipid membrane. The electron densities show seven peaks reflecting the seven a-helices which are predicted to cross the cell membrane. In (b) is shown a helical-wheel diagram of the receptor orientated according to the electron density map shown in (a). The diagram is seen as the receptor would be viewed from outside the cell membrane. The agonist binding pocket is illustrated by the hatched region between TM3, TM5 and TM6. (From Schertler et al. 1993 and Baldwin 1993, reproduced from Schwartz 1996). Reprinted with permission from Textbook of Receptor Pharmacology. Eds Foreman, JC and Johansen, T. Copyright CRC Press, Boca Raton, Florida...

WHEEL-SHAPED POLYOXO AND POLYOXOTHIOMETALATES FROM THE MOLECULAR LEVEL TO NANOSTRUCTURES... 

Synthesis of the big wheels , in addition to the intellectual satisfaction it produces, will serve in the future as a mini-reactor to perform hydrolysis reactions at the molecular level. Their colloidal solutions... 

Macrocyclic receptors made up of two, four or six zinc porphyrins covalently connected have been used as hosts for di- and tetrapyridyl porphyrins, and the association constants are in the range 105-106 M-1, reflecting the cooperative multipoint interactions (84-86). These host-guest complexes have well-defined structures, like Lindsey s wheel and spoke architecture (70, Fig. 27a), and have been used to study energy and electron transfer between the chromophores. A similar host-guest complex (71, Fig. 27b) was reported by Slone and Hupp (87), but in this case the host was itself a supramolecular structure. Four 5,15-dipyridyl zinc porphyrins coordinated to four rhenium complexes form the walls of a macrocyclic molecular square. This host binds meso-tetrapyridyl and 5,15-dipyridyl porphyrins with association constants of 4 x 107 M-1 and 3 x 106 M-1 respectively. 

The velocity distributions of both the metal and molecular beams were measured using the same slotted chopper wheel described above by... 

Figure 89 The motorized nanocar structure (172) that contains a light-activated unidirectional molecular motor and an oligo(phenylene ethynylene) chassis and axle system with four carboranes to serve as the wheels. (Adapted from ref. 168.)... 

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