Poly-oxo anion chemistry
These anions are soluble clusters of metal and oxygen atoms whose symmetric structures are related to the insoluble metal oxides (eg, see structure of [H2W12O40]6- in Figure 1).
As they are cheap, robust and non-toxic, they are used commercially as acid and oxidation catalysts. It is now possible to study catalytic cycles in the gas phase (!!) by mass spectrometry (eg, see Figure 2)[1] providing new molecular insights. These insights assist design of new green catalytic processes [2].
In addition, the clusters are highly redox-active (can be oxidised and reduced) and photo-active. These properties have led to very promising and simple photo-catalysts which use light as an energy source [3]. The redox reactivity of the anions in new environmentally friendly solvents ('ionic liquids') is being explored.[4]
We are currently searching for new materials, new structures and new chemistry.[5,6]
Bio-inorganic chemistry
Nutrient trace metals are needed for enzymes by living organisms but are toxic in excess. Acquisition of the metals is mediated by molecular pumps and by transport proteins (chaperones: Figure 3) which take the metal to its destinations in biological cells. Defects in copper metabolism cause Menkes and Wilson diseases in humans and are components of certain neurodegenerative diseases (Alzheimer, Creutzfeldt- Jakob, mad cow).
The molecular pump Ctr1 (Copper Transporter No.1) is being studied as it is primarily responsible for import of copper into yeast and mammalian cells. It appears to interact with the chaperones via a Cu6S6 cluster !! (Figure 4)[7]. In addition, the cancer drug cis-platin enters cells via the Ctr1 pump. A new project is underway to understand why both nutrient copper and cis-platin use the same entry pump. This may help to design drugs with fewer side effects.
The proteins are generated via molecular genetics and then highly purified. The molecular probes needed are provided by techniques such as NMR, ESR, MS, fluorescence, X-ray crystallography and electrochemistry.
Paper[8] provides examples of the approach.
|
|
Figure 1: The [H2W12O40]6- anion |
Figure 2: catalytic oxidation of CH3.OH |
| |
|
|
|
Figure 3: Copper transport protein |
Figure 4: The Cu6S6 cluster in Ctr1 (Cu atoms are pink). |
Selected Publications
- Waters, T.; O´Hair, R. A. J.; Wedd, A. G., J. Amer. Chem. Soc. 2003, 125, 3384-3396.
- Feyel, S; Waters, T.; O´Hair, R. A. J.; Wedd, A. G., J.C.S. Dalton Transactions 2004, 4010-4016.
- Rüther, T.; Bond, A. M.; Wedd, A. G., J. Amer. Chem. Soc. 2003, 125, 10133-10143.
- Mariotti, A. W. A.; Wedd, A. G. et al, Analyt. Chem. 2002, 74, 3151-3156.
- Waters, T.; O´Hair, R. A. J.; Wedd, A. G. et al, J. Amer. Chem. Soc. 2004, 126, 5119-512
- Keyes, T.E.; Bond, A. M.; Wedd, A. G. et al, J. Phys. Chem. A 2004, 138, 7399-7405.
- Xiao, Z.; Wedd, A. G. et al, J. Amer. Chem. Soc. 2004, 126, 3801-3809.
- Cross, M.; Xiao, Z.; Wedd, A. G. et al, J. Biol. Inorg. Chem., 2001, 6, 638-649; 2002, 7, 781-790.
|
top of page
