The Rzepa research group is a member of the synthesis section in the department of Chemistry, Faculty of Natural Sciences. The group is interested in molecules, and in particular modelling their shapes, properties and reactions. The example currently showcased below involves modelling the key transition state in the catalytic polymerisation of lactide to polylactide, a new generation of bio-sustainable polymer not dependent on oil. This particular Magnesium-based catalyst produces heterotactic polymer, where the configuration of the lactide units alternates in the polymer chain, in the manner RR, SS, RR, SS, etc. Understanding why this happens was achieved using quantitative modelling, derived from accurate quantum mechanical (density functional) calculations of the reaction mechanism. This was published as: Gibson, Vernon C.; Marshall, Edward L.; Rzepa, Henry S. "A computational study on the ring-opening polymerization of lactide initiated by beta-diketiminate metal alkoxides: The origin of heterotactic stereocontrol", J. Am. Chem. Soc., 2005, 127, 6048-6051. DOI: 10.1021/ja043819b and 10.1021/ja061400a
A second theme has been the exploration of a fundamentally new form of aromaticity which has the property of chirality (dissymetry). These helical aromatics derive from Mobius topologies, and our work has extended the categorisation of such systems from single half twist, to double (lemniscular) systems, and even higher up to six half twists. We have reviewed the area (DOI: 10.1021/cr030092l) and introduced a new topological metric of aromaticity based on writhe (DOI: 10.1021/ja710438j).
Since 1993, we have been pioneers in presenting such chemical stories in Internet-friendly ways. The environment in which the Web page you are currently viewing is embedded unfortunately does not readily lend itself to "molecular interactivity". You are encouraged to also visit an alternative page at www.ch.ic.ac.uk/rzepa/ to view and manipulate a 3D model of the molecule described above, along with much other information about the activities of the group.
et al., 2014, The Nature of the Fourth Bond in the Ground State of C-2 : The Quadruple Bond Conundrum, Chemistry - A European Journal, Vol:20, ISSN:0947-6539, Pages:6220-6232
Rzepa HS, 2011, Can 1,3-dimethylcyclobutadiene and carbon dioxide co-exist inside a supramolecular cavity?, Chemical Communications, Vol:47, ISSN:1359-7345, Pages:1851-1853
Kong J, Schleyer PVR, Rzepa HS, 2010, Successful Computational Modeling of Isobornyl Chloride Ion-Pair Mechanisms, Journal of Organic Chemistry, Vol:75, ISSN:0022-3263, Pages:5164-5169
Rzepa HS, 2010, The rational design of helium bonds, Nature Chemistry, Vol:2, ISSN:1755-4330, Pages:390-393
et al., 2010, A Tricyclic Aromatic Isomer of Hexasilabenzene, Science, Vol:327, ISSN:0036-8075, Pages:564-566
Rzepa HS, 2009, Wormholes in chemical space connecting torus knot and torus link pi-electron density topologies, Physical Chemistry Chemical Physics, Vol:11, ISSN:1463-9076, Pages:1340-1345
Allan CSM, Rzepa HS, 2008, Chiral Aromaticities. A Topological Exploration of Mobius Homoaromaticity, Journal of Chemical Theory and Computation, Vol:4, ISSN:1549-9618, Pages:1841-1848
Rzepa HS, 2008, Linking number analysis of a pentadecanuclear metallamacrocycle: A Mobius-Craig system revealed, Inorganic Chemistry, Vol:47, ISSN:0020-1669, Pages:8932-8934
Allan CSM, Rzepa HS, 2008, Chiral aromaticities. AIM and ELF critical point and NICS magnetic analyses of Mobius-type aromaticity and homoaromaticity in lemniscular annulenes and hexaphyrins, Journal of Organic Chemistry, Vol:73, ISSN:0022-3263, Pages:6615-6622
Rappaport SM, Rzepa HS, 2008, Intrinsically chiral aromaticity. Rules incorporating linking number, twist, and writhe for higher-twist Mobius annulenes, Journal of the American Chemical Society, Vol:130, ISSN:0002-7863, Pages:7613-7619
Allan CSM, Rzepa HS, 2008, A computational investigation of the structure of polythiocyanogen, Dalton Transactions, ISSN:1477-9226, Pages:6925-6932