Crystallographic poly

Derivatives in the s- and p-Block Elements Supported by Poly(pyrazolyl)borato Ligation Models for Carbonic Anhydrase, Receptors for Anions, and the Study of Controlled Crystallographic Disorder Gerard Parkin... 

Crystallographic study of 2,5-DSP and poly-2,5-DSP demonstrated that the polymerization proceeded with retention of the space group (Pbca) of the starting 2,5-DSP crystal (Sasada et al., 1971 Nakanishi et al., 1972a). The result was the first evidence of an organic reaction which proceeded in the crystal lattice. 

After the first report on the crystal structure correlation between 2,5-DSP and poly-2,5-DSP crystals, a different crystallographic result was reported on a poly-2,5-DSP crystal (Meyer et al., 1978). It was reconfirmed, however, that the first structural analysis was correct (Nakanishi et al., 1979a). 2,5-DSP, crystallized from benzene solution, is highly photoreactive (a-form), while the same compound, sublimed at a rather high temperature... 

Of further particular interest was that the crystallographic results on 2,5-DSP and poly-2,5-DSP had pointed out a very important future possibility that an absolute asymmetric synthesis could be achieved if any prochiral molecule, e.g. an unsymmetrical diolefin derivative, could be crystallized into a chiral crystal and if the reaction of the chiral crystal proceeded in the same manner as the 2,5-DSP crystal with retention of the crystal lattice (Wegner, 1972, 1973). Such types of absolute asymmetric synthesis with a high enantiomeric yield have now been performed by topochemical [2+2] photoreaction of unsymmetric diolefin crystals (Addadi etal., 1982 Hasegawa et al., 1990 Chung et al., 1991a,b). 

The drop of the voltammetric crurent is associated with Pt surface oxidation, and the drop on the negative-going mn is due to Reaction (12.9) (surface poisoning by CO) and the Tafehan kinetics of Reaction (12.8). Further, the shift between curves in Fig. 12.13a and b indicates that in the potential range between 0.5 and 0.6 V, methanol oxidation occms with zero or low level atop CO smface intermediate. The amplitudes on Fig. 12.13 on both scans nearly equal to each other indicate a high level of preferential (111) crystallographic orientation of the poly crystalline Pt surface used for this work, as inferred from data in [Adzic et al., 1982]. 

ALKYL, HYDRIDE, AND HYDROXIDE DERIVATIVES OF THE s- AND p-BLOCK ELEMENTS SUPPORTED BY POLY(PYRAZOLYL)BORATO LIGATION MODELS FOR CARBONIC ANHYDRASE, RECEPTORS FOR ANIONS, AND THE STUDY OF CONTROLLED CRYSTALLOGRAPHIC DISORDER... 

Infrared spectroscopy has been widely used for the qualitative and quantitative characterization of polymorphic and pseudopolymorphic compounds of pharmaceutical interest. Since solid state IR can be used to probe the nature of (pseudo)polymorphism on the molecular level, this method is particularly useful in instances where full crystallographic characterization of (pseudo)poly-morphism was not found to be possible. Recently, a significant number of publications have appeared that discuss where a multidisciplinary, spectroscopic... 

Last but not least, a very intriguing terpenoid pyrrolidine alkaloid, poly-zonimine was milked from the millipede Polyzonium rosalbum (148). The structural formula of polyzonimine (118) is based on an X-ray crystallographic analysis of its perchlorate and by a total synthesis. 

A series of compounds that has been studied extensively, both theoretically and experimentally, is the poly phenyls (38-40). In considering these compounds it is very helpful if one has at least a little understanding of the significance of the X-ray crystallographic results. Biphenyl, the first of the series, is known to be nonplanar in the gas phase, with a torsional angle about the central bond of 42°. This is interpreted in terms of relief of steric interference between the... 

In the case of crystals, both intramolecular (conformational) and packing energies should be taken into account simultaneously. Such a total energy minimization method, with suitable crystallographic constraints, has been applied in different steps of the analysis of crystalline structures of three different synthetic polymers. Structures of these molecules, namely, isotactic trans-1,4-poly-penta-1,3-diene (ITPP), poly-pivalolactone (PPVL), and isotactic cis-1,4-poly(2-methyl-penta-1,3-diene)(PMPD), do not have troublesome features such as charged groups, counterions, and solvent molecules. 

Fig. 3a, b Crystal structures of 2 and poly(2) viewed down along the crystallographic a- and h-axes at the top and bottom, respectively. Hydrogen atoms are omitted for clarity, c ORTEP drawing for 2 (-120 °C) and repeating unit of poly(2). Thermal ellipsoids are plotted at the 50% probability level [56]... 

In acidic solutions, the corrosion rate is relatively high. Studies on cadmium monocrystals and polycrystals in acidic chloride solutions revealed anodic dissolution independent of the crystallographic orientation the dissolution rate was controlled by the mass transport of CdCl" ions [331]. The inhibitive influence of adsorbed organic substances, for example, alcohols [332], phenotiazine [333], and some polymers (e.g. poly (vinyl alcohol), poly(acrylic acid), sodium polyacrylate. 

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