Topics in Current Chemistry

· · · ·
Latest release: June 2, 2016
Series
140
Books
Design of Organic Solids
Book 198·Sep 2003
0.0
·
Considering the high level of our knowledge concerning covalent bond formation in the organic chemistry of molecules, our understanding of the principles involved in organic solid design is almost in its infancy. While chemists today are able to synthesize organic molecules of very high complexity using sophisticated methods of preparation, they lack general approaches enabling them to reliably predict organic crystalline or solid structures from molecular descriptors - no matter how simple they are. On the other hand, nearly all the organic matter surrounding us is not in the single-molecule state but aggregated and condensed to form liquid or solid molecular assemblages and structural arrays giving rise to the appearances and properties of organic compounds we usually observe. Obviously, the electrical, optical or magnetic properties of solid organic materials that are important requirements for future technologies and high-tech applications, as well as the stability and solubility behavior of a medicament depend on the structure of the molecule and the intramolecular forces, but even more decisively on the intermolecular forces, i. e. the packing structure of the molecules to which a general approach is lacking. This situation concerned ]. Maddox some years ago to such a degree that he described it as "one of the continuing scandals in the physical sciences" [see (1998) Nature 335:201; see also Ball, P. (1996) Nature 381:648]. The problem of predicting organic solid and crystal structures is very dif- cult.
Modern Solvents in Organic Synthesis
Book 206·Jul 2003
0.0
·
In recent years the choice of a given solvent for performing a reaction has become increasingly important. More and more, selective reagents are used for chemical transformations and the choice of the solvent may be determining for reaching high reaction rates and high selectivities. The toxicity and recycling considerations have also greatly influenced the nature of the solvents used for industrial reactions. Thus, the development of reactions in water is not only important on the laboratory scale but also for industrial applications. The p- formance of metal-catalyzed reactions in water for example has led to several new hydrogenation or hydroformylation procedures with important industrial applications. The various aspects of organic chemistry in water will be prese- ed in this book. Recently, novel reaction media such as perfluorinated solvents or supercritical carbon dioxide has proven to have unique advantages leading to more practical and more efficient reactions. Especially with perfluorinated solvents, new biphasic catalyses and novel approaches to perform organic reactions have been developed. These aspects will be examined in detail in this volume. Finally, the performance of reactions in the absence of solvents will show practical alternatives for many reactions. More than ever before, the choice of the solvent or the solvent system is ess- tial for realizing many chemical transformations with the highest efficiency. This book tries to cover the more recent and important new solvents or solvent systems for both academic and industrial applications.
Bioorganic Chemistry of Biological Signal Transduction
Book 211·Jul 2003
0.0
·
The transduction of signals from the extracellular space across the plasma membrane into the interior of cells and ultimately to the nucleus, where in - sponse to such external signals the transcription of the genetic code is inf- enced, belongs to the most fundamental and important events in the regulation of the life cycle of cells. During recent years several signal transduction cascades have been elucidated which regulate, for instance, the growth and the prolife- tion of organisms as diverse as mammals, flies, worms and yeast. The general picture which emerged from these investigations is that nature employs a c- bination of non-covalent ligand/protein and protein/protein interactions together with a set of covalent protein modifications to generate the signals and transduce them to their destinations. The ligands which are recognized may be low molecular weight compounds like lipids, inositol derivatives, steroids or microbial products like cyclosporin. They may be proteins like, for instance, growth factors or intracellular adaptor proteins which carry SH2 or SH3 domains, and they may be specific DNA stretches which are selectively rec- nized by transcription factors. These and other aspects of biological signal transduction provide an open and rewarding field for investigations by scientists from various different dis- plines of biology, medical research and chemistry working in academic research institutions or in industry.