Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. . The crystal structure of 2a reveals that only one quadrant is blocked. Asymmetric hydrogenation of acrylic esters and enamides using 3a and 3b as catalysts show that the phenylene-backboned diphosphine gives a more efficient catalyst in terms of asymmetric induction than the more flexible ferrocene-backboned diphosphine.The best results, which were obtained with 3a and enamide substrates, exceeded those obtained with Duphos catalysts. The rate of hydrogenation of the enamides with 3a was 10 times faster than with [Rh(Duphos)(diene)][BF 4 ]. A quadrant diagram can be used to predict the configuration of the major product, provided it is assumed to be derived from the less sterically congested intermediate.
The Austin Maze is a complex visuo-spatial learning task commonly used in neuropsychological assessment. To some extent its use has been hampered by a lack of available normative data. In this study 109 normal young adults were assessed on the maze and 95 subjects were reassessed one month later to provide information on the number of trials required to reach criterion and the savings in learning at reassessment. Results of the study are provided.
The synthesis of mesomorphic transition metal complexes is a research area experiencing continuous expansion." The growing interest in these new materials is a consequence of both their peculiar physical properties and, from the point of view of the chemistry involved, the wide range of synthetic possibilities that still have to be explored. Properties such as high birefringence,[61 high linear['] and nonlinear['] polarizability, and high linear dichroi~m [~] have been observed and metal complexes capable of forming lyotropic liquid crystal mesophases ["] have been prepared.Over the last few years effort has been invested in the synthesis of thermotropic, calamitic liquid-crystalline complexes with high coordination numbers. However, most of these compounds are square pyramidal complexes of V' " or Fe"' or ferrocene derivatives." '-Recently, we have shown that the combination of ligands with high structural anisotropy and relatively bulky organometallic fragments such as [M(CO),] (M = Mn, Re) leads to the formation of calamitic liquid-crystalline complexes with octahedral coordination around the metallic center.[l3] In particular, the compounds [ML(CO),] (L = Schiff base) show mesomorphic properties when three['41 or rings are included in the ligand structure (Fig. 1).We wished to extend this work with the aim of generating a general approach to the design and synthesis of metalcontaining liquid crystals based on high coordination number centers and therefore devised a methodology for the synthesis of liquid-crystalline complexes obtained by coordination of the [ReBr(CO),] fragment to 1,4-diaza-I ,3-butadienes. Diazabutadienes have a wide and interesting coordination chemistry which has been subject of several studies [16]
Proteolytic cleavage of the bacterial protein toxin pneumolysin with protease K creates two fragments of 37 and 15 kDa. This paper describes the purification of these two fragments and their subsequent physical and biological characterisation. The larger fragment is directly involved in the cytolytic mechanism of this pore-forming protein, via membrane binding and self-association. The smaller fragment lacks ordered structure or discernible activity.
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