Computational Studies of the Chemistry of Condensed
Phases (1992-1995)
EPSRC grant GR/H07207
Investigators: Dr P.M. Rodger, Dr M.G.B. Drew, Dr P.C.H. Mitchell
Department of Chemistry, University of Reading
Contact: Dr P.M. Rodger
Aims and Objectives: This grant provided a suite of graphics workstations to develop
and continue our computational studies of a range of condensed phase properties,
including clathrates, host/guest complexes, catalyst surfaces, colloidal aggregates,
biological amorphous solids, and inorganic solids.
Summary of the Research: This grant provided a part of the hardware infrastructure
around which we have built an active and vibrant computer modelling group, with
research expertise in a wide range of condensed phase phenomena. Emphasis has been
placed on combining experimental and modelling studies, both to validate the
computational procedures used, and to maximise the information that can be gleaned
from the experiment. Such comparisons have also served to optimise predictive
applications for our calculation methodology.
This grant has provided partial support for a wide range of different research projects.
Three specific examples are given below, but details of other projects can be obtained
from the investigators on request.
Clathrate hydrates: Clathrate hydrates are a form of inclusion compound in which a
water host lattice entraps small non- or weakly-polar guest molecules. An important
example is methane hydrate, the formation of which can cause difficulties in
petrochemical exploration and transport. Research in this area has a double focus: (1)
improving methods of predicting the conditions under which hydrates will be stable, and
(2) designing molecules that will allow control of the formation conditions. Our group
has been active in both of these areas. We have successfully adapted recent developments
in solid-state free energy calculations to apply them to water-based solids, and have used
them to produce the first first-principles calculation of a hydrate/ice coexistence curve.
Detailed analysis of these calculations is also helping us to identify methods of improving
the empirical methods commonly used to predict hydrate formation in the petrochemical
industry. using our expertise in molecular recognition, we have also been active in
improving computational methods for designing hydrate inhibitors.
Metal extraction: We have developed a number of molecules that will selectively extract
a range of metal ions. For transition metals this has been achieved by exploiting the
clearcut stereochemical preferences of the metal for specific metal-donor atom bond
lengths and geomtry. Our work on lanthanides and actinides has proved more difficult,
due to the low stereochemical discrimintation exhibited by such metal-ligand
interactions. By developing a new force field suitable for lanthanide complexes, and
validating this by modelling known complex structures, we have been able to design a
molecule based on a substituted calix[4]arene with sufficient preorganisation in the donor
set to preclude complex formation with unwanted metals, and with enough flexibility to
provide the required coordination for lanthanides. The complex has since been
synthesised and shown to give good extraction results in trial experimental studies.
Sulfide catalysis: MoS2 based catalysts are important industrial catalysts used in the
removal of sulfur compounds from crude petroleum by hydrogenolysis. Our modelling
has focused on: determining the preferred structure and electronic properties of the active
phase; and investigating the mode of binding of the manner in which a reactant molecule
becomes activated. Ab initio density functional calculations have been carried out on a
range of different MoS2 catalyst systems. A particular success of this work has been our
ability to calculate the observed inelastic neutron scattering spectrum for these
compounds; this has been important in validating the computational methods, but has
also led to much greater elucidation of the experimental spectra. We have also been able
to match the charge distribution on the molecule with the charge distribution on the
catalyst surface thereby arriving at a likely mode of interaction. Based on these studies,
we are now extending computational methods developed in molecular recognition
problems for application to catalysis.
Selected Publications
1. Circular dichroism as a probe of chiral solvent structure around chiral molecules;
J. Fidler, P.M. Rodger, A. Rodger, J. Chem. Soc., Perkin Trans 2, 1993, 235
2. Intercalation of cobalt phthalocyanine into the layered host material antimony
hydrogen phosphate hsb(po4)2 insitu synthesis of guest molecules; M.J. Hudson,
W.J. Locke, P.C.H. Mitchell, X.M. Hu, Solid State Ionics, 1993, 131
3. Bound water in aged molybdate alumina hydrodesulfurization catalysts an
inelastic neutronscattering study; P.C.H. Mitchell, J. Tomkinson, J.G. Grimblot,
E. Payen J. Chem. Soc., Faraday Trans., 1993, 1805
4. Molecular Mechanics Studies of the Conformations of Metal Complexes of
1,4,7,10,13,16-hexaazacyclooctane; Drew, M.G.B. and Santos, M.A., Struct.
Chem. 1993, 4, 5.
5. Experimental and Computer Modelling Studies of Carbon Supported Metal
Complexes, Part 2- Molecular Mechanics Study of the Adsorption of
Tetraaza[14]annulenes and their nickel(II) complexes by a carbon surface; Drew,
M.G.B., Jutson, N.J., Mitchell, P.C.H., Potter, R.J. and Thompsett, J. Chem. Soc.
Faraday Trans 1993, 89, 3963
6. Theoretical Calculations of Cyclohexaglycine and three-dimensional derivatives.
Conformational Analysis and Calculations of host-guest properties of peptides;
Santos, M.A., Brennan, R.L. and Drew, M.G.B., J. Mol. Struct. (Theochem) 1993,
286, 109
7. A comparison of methods for the computer modelling of crystal structures; Cragg,
P.J. and Drew, M.G.B., J. Comp-Aided Materials Design, 1993, 149
8. Towards a microscopic understanding of clathrate hydrates; P.M. Rodger, Annals
N.Y. Acad. Sci., 1994, 715, 207
9. Chiral solvent structure around chiral solvent molecules: experimental and
theoretical study; J. Fidler, P.M. Rodger, A. Rodger, J. Am. Chem. Soc., 1994,
116, 7266
10. Direct free energy calculations for clathrate hydrates; R.E. Westacott, P.M.
Rodger, Annals N.Y. Acad. Sci., 1994, 715, 537
11. Conformational Study of the Macrocycle 1,4,7-trithiacyclononane in Metal
Complexes; Beech, J., Cragg, J. and Drew, M.G.B., J. Chem. Soc. Dalton Trans,
1994, 719
12. Computer Modelling Studies of 18-crown-6 with urea and thiourea; Drew,
M.G.B., Lund, A and Nicholson, D.G., Supramol. Chem., 1994, 3, 211
13. Structures of potassium encapsulated within the 1,3-alternate conformation of
calix[4]arenes; P.D. Beer, M.G.B. Drew, P.A. Gale, P.B. Leeson, M.I. Ogden, J.
Chem. Soc., Dalton Trans, 1994, 3479
14. Catalytic chemistry of furan and thiophene. Ab initio calculations using the
spincoupled valence bond method of the interaction between furan and thiophene
and a positivelycharged centre; P.C.H. Mitchell, G.M. Raos, P.B. Karadakov, J.
Gerratt, D.L. Cooper J. Chem. Soc. Faraday Trans., 1995, 91, 749
15. Computer modelling of a molybdenum disulfate catalyst: density functional
calculations on molybdenumsulfur clusters; P.C.H. Mitchell, C. Plant. Proc. Vth
Workshop Hydrotreating Catalysts: Bul. Soc. Chim. Belg., 1995, 104, 293
16. Interaction of thiophene with a molybdenum disulfate catalyst: an inelastic
neutron scattering study; P.C.H. Mitchell, D.A. Green, J.G. Grimblot, E. Payen, J.
Tomkinson, Proc. Vth Workshop Hydrotreating Catalysts: Bul. Soc. Chim. Belg.,
1995, 104, 325
17. Inelastic neutron scattering studies of catalysts; P.C.H. Mitchell, Acta Phys.
Hung., 1995, 75, 131.
18. Detection of Creatinine by a designed receptor; Bell, T.W., Drew, M.G.B., Luo,
Y, Chapoteau, E., Czech, B.P. and Kumar, A., Science, 1995, 259, 671
19. Inhibition of Crystal Growth in Methane Hydrate; Carver, T.J., Drew, M.G.B. and
Rodger, P.M., J. Chem. Soc. Faraday Trans, 1995, 91, 3449.
20. Monte Carlo Simulations of the First Order Phase Transition in Vanadium
Dioxide; Drew, M.G.B. and Slater,B., Phil. Mag B, 1996, 73, 59