Molecules-of-the-month (Imperial)A Project started in December 1995 by Henry Rzepa (Imperial College) and Paul May (Bristol University)Sharpless asymmetric epoxidation- December 10, 2003 The Sharpless asymmetric epoxidation of allylic alcohols. This discussion is based on the paper by Y.D. Wu and D. Lai, J.Amer.Chem.Soc. 117 11327 (1995), a DFT study on the selectivity of this reaction. The structure below is not the outcome of their calculations; it is a hand-made reconstruction of the complex they suggest as a transition state that explains the experimental findings.http://www.ch.ic.ac.uk/motm/borkent/sharpless.html Spiroidal Graphite- December 10, 2003 Helicoidal Graphite, otherwise known as helical bucky tubeshttp://www.ch.ic.ac.uk/motm/spirala.html Molecular Mobius strips- December 10, 2003 With the current interest in so called "nanoscale" devices with dimensions reaching down to molecular sizes, there exists a fascinating boundary between the shapes that materials (i.e. a large collection of molecules) and molecules themselves can adopt. Understanding how molecular building blocks can be used to construct nanoscale devices is the key to understanding nanotechnology. A second boundary exists, between idealised shapes, or topologies, defined by mathematical equations,...http://www.ch.ic.ac.uk/motm/trefoil/ Viagra- December 10, 2003 Sildenafil, trade name VIAGRATM, chemical name 5-2-ethoxy-5-(4-methylpiperazin-1-ylsulfonyl)phenyl-1-methyl-3-propyl-1,6-dihydro-7H-pyrazolo4,3- dpyrimidin-7-one, formula C22H30N6O4S, was discovered through a rational drug design programme by the pharmaceutical company Pfizer.http://www.ch.ic.ac.uk/motm/viagra.html Chiral cyclo-octene- December 10, 2003 Nature is not symmetrical at least at the molecular level. Pasteur was one of the first to spot this in the asymmetry of tiny crystals of tartaric acid salts. The DNA double helix tends to spiral only one way even though it would be just as easy for it to twirl the other while nature almost invariably uses only the left-handed form of the amino acids to build its proteins. Numerous theories exist that attempt to explain the bias which lies at the very roots of life itself but now Japanese...http://www.ch.ic.ac.uk/motm/cyclooctene.html Nanobiotics- December 10, 2003 Conventional anti-biotics such as penicillins etc function metabolically, by interfering with bacterial synthesis of the cell wall. Many bacteria have evolved to develop resistance to common anti-biotics, and some bacterial are resistent to most. In 1993, a new approach to developing such agents was pioneered. Reza Ghadiri at the Scripps Research Institute in California developed a series of cyclic peptides using a combination of the natural (l) form with the un-natural (d) amino acid...http://www.ch.ic.ac.uk/motm/nanobiotic/ Anthracene Resorcinol with cyclohexadiene and ethyl acrylate in cavity- December 10, 2003 A pericyclic reaction is one in which bonds are made or broken in a concerted cyclic transition state. The accepted wisdom for such reactions is that they have several characteristic properties, once of which is that no catalyst is needed to promote the reactions. In the last twenty years however, many examples of catalysed pericyclic reactions have been discovered, included those mediated by transition metals, and by metals acting as Lewis acids. It has also been known for some time that it is.http://www.ch.ic.ac.uk/motm/cavities.html |