Research Network for Metals in Medicine

 

 

Dr Cameron Keppert

BSc(Hons), PhD(Lond)

Position: Senior Lecturer, Chemistry

Affiliation: University of Sydney, School of Chemistry

Postal Address:
School of Chemistry, Building F11
University of Sydney, NSW, 2006
AUSTRALIA

Phone: +61 (02) 9351 5741
Fax: 9351 3329
Email: c.kepert@chem.usyd.edu.au
Webpage: http://www.chem.usyd.edu.au/about/staff_kepert.html

Research Profile

Areas of interest:

  • Materials chemistry
  • Molecular framework materials
  • X-ray diffraction
  • Microporosity
  • Electronic and magnetic properties of solids
  • Phase transitions (structural, electronic and magnetic)

Research:

Microporous Molecular Frameworks: Molecular framework materials are crystalline solids that contain extended networks constructed by the linkage of metal atoms by multiply-coordinating polydentate ligands. A rapid growth in the study of these materials has arisen from the realisation that metal-organic framework synthesis offers considerable flexibility and control over structure and properties, thereby offering rare pathways to rational materials design. This flexibility originates from the enormous structural and chemical diversities afforded by molecular systems, features that are less prevalent in many other branches of materials chemistry.

The recent emergence of microporosity in molecular frameworks has led to widespread speculation that such materials may be ideally suited for applications such as molecular separation, sensing and heterogeneous catalysis. Our primary research efforts are being directed towards exploring these issues, addressing, in particular, whether there are any limitations to this porosity and to what extent the frameworks may be thought of as rigid. Experimentation involves the synthesis of new materials by diffusion-controlled and solvothermal methods, and structural and physical characterisations using techniques that include single crystal and powder X-ray diffraction, vibrational spectroscopy (IR and Raman), TGA/DSC of guest desorption and sorption, NMR, SQUID magnetometry, EPR and theoretical modelling of guest molecule docking and packing.

Chiral Phases: The search for chiral microporous materials, widely regarded as a Holy Grail within solid state chemistry, is driven by the potential application of such materials for chiral separations and enantioselective syntheses. We have recently made significant in-roads into this area by developing a large and diverse array of porous, chiral molecular framework solids, including some that are the only such materials known that can be synthesised homochirally. Experiments show that these materials display a high degree of selectivity to molecular guest-exchange, as well as retaining structural framework integrity with guest removal. Investigations into the direct application of these phases for enantioseparation are underway, with an aim towards designing systems for the separation of small drug-precursor molecules.

In-situ Structural Investigations: We have recently performed unique in-situ single crystal X-ray diffraction experiments into guest desorption to demonstrate the microporosity of specific molecular framework materials. These studies are noteworthy in providing the first quantitative proof that desolvated phases of both co-ordination and hydrogen-bonded framework lattices may be robust enough to support large regions of complete void, thereby drawing a direct link with more conventional microporous materials such as zeolites. Such studies are being combined with in-situ techniques such as DSC/TGA, vibrational spectroscopy, NMR and molecular modelling to generate an overall picture that combines structural information with an understanding of the selectivity, dynamics and energetics of guest-exchange.

Electronic and Magnetic Properties: The incorporation of atomic or molecular constituents with electronic or magnetic function (e.g., localised electrons, delocalised pI-systems, redox-active species, etc.) into molecular frameworks is being investigated with an aim towards constructing materials with novel electronic and magnetic properties. The vast control over structure and chemical functionality that is afforded by this molecular approach allows the property-directed design and synthesis of new magnetic and electronic materials, including, importantly, the possible combination of these properties with microporosity.



Selected Publications

  1. G.J. Halder, C.J. Kepert, B. Moubaraki, K.S. Murray, J.D. Cashion, "Guest-Dependent Spin Crossover in a Nanoporous Molecular Framework Material", Science, 298, 1762-1765 (2002).
  2. M.M. Turnbull, C.P. Landee, "Porous Materials with a Difference", Science 298 1723-1724 (2002).
  3. E.J. Cussen, J.B. Claridge, M.J. Rosseinsky, C.J. Kepert, "Flexible Sorption and Transformation Behavior in a Microporous Metal-Organic Framework", J. Am. Chem. Soc, 124, 9574-9581 (2002).
  4. A.J. Fletcher, E.J. Cussen, T.J. Prior, M.J. Rosseinsky, C.J. Kepert, K.M. Thomas, "Adsorption Dynamics of Gases and Vapours on Ni2(4,4'-bipyridine)3(NO3)4: a Nanoporous Metal Organic Framework Material", J. Am. Chem. Soc., 123, 10001-10011 (2001).
  5. A. Rujiwatra, C.J. Kepert, J.B. Claridge, M.J. Rosseinsky, H. Kumagai, M. Kurmoo, "Layered Cobalt Hydroxysulfates with both Rigid and Flexible Organic Pillars: Synthesis, Structure, Porosity, and Cooperative Magnetism", J. Am. Chem. Soc., 123, 10584-10594 (2001).
  6. C.J. Kepert, T.J. Prior, M.J. Rosseinsky, "A Versatile Family of Interconvertible Microporous Chiral Molecular Frameworks: The First Example of Ligand Control of Network Chirality", J. Am. Chem. Soc., 122, 5158-5168 (2000).
  7. C.J. Kepert, T.J. Prior, M.J. Rosseinsky, "Hydrogen Bond Directed Hexagonal Frameworks based on Coordinated 1,3,5-Benzenetricarboxylate", J. Solid State Chem., 152, 261-270 (2000).
  8. C.J. Kepert, M.J. Rosseinsky, "Zeolite-like Crystal Structure of an Empty Microporous Molecular Framework", Chem. Commun., 375-376 (1999).
  9. A. Rujiwatra, C.J. Kepert, M.J. Rosseinsky, "The Novel Organo-Pillared Porous Magnetic Framework Co4(SO4)(OH)6(H2NC2H4NH2)0.5.3H2O", Chem. Commun., 2307-2308 (1999).
  10. C.J. Kepert, D. Hesek, P.D. Beer, M.J. Rosseinsky, "Desolvation of a Novel Microporous Hydrogen-Bonded Framework: Characterization by In Situ Single-Crystal and Powder X-ray Diffraction", Angew. Chem. Int. Ed. Engl., 37(22), 3158-3160 (1998); Angew. Chem., 110(22), 3335-3337 (1998).
  11. C.J. Kepert, M.J. Rosseinsky, "A Porous Chiral Framework of Coordinated 1,3,5-Benzenetricarboxylate: Quadruple Interpenetration of the (10,3)-a Network", Chem. Commun., 31-32 (1998).
  12. C.J. Kepert, M. Kurmoo, P. Day, "Crystal Structures and Physical Properties of BEDT-TTF Charge Transfer Salts with [Mo6Cl8]X62- Anions (BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene; X = Cl, Br)", Proc. Roy. Soc. Lond. A, 454, 487-518 (1998).
  13. M. Kurmoo, C.J. Kepert, "Hard Magnets Based on Transition Metal Complexes with the Dicyanamide Anion, [N(CN)2]-", New J. Chem., 1515-1524 (1998).
  14. C.J. Kepert, M. Kurmoo, P. Day, "BEDT-TTF Charge Transfer Salts of [Re2(NCS)10]n- (n=2,3)", Inorg. Chem., 36(6), 1128-1135 (1997).
  15. C.J. Kepert, M. Kurmoo, M.R. Truter, P. Day, "Quasi-One-Dimensional BEDT-TTF (bis(ethylenedithio)tetrathiafulvalene) Charge Transfer Salts with Paramagnetic Group 6 Anions", J. Chem. Soc., Dalton Trans., 607-613 (1997).
  16. C.J. Kepert, M. Kurmoo, P. Day, "Semiconducting Charge Transfer Salts of BEDT-TTF (bis(ethylenedithio)tetrathiafulvalene) with Hexachlorometallate(IV) Anions", J. Mater. Chem., 7(2), 221-228 (1997).