Structure, mechanism and exchange processes in molecules

Structure, mechanism and exchange processes in molecules

Using NMR spectroscopy as our primary tool, backed up wuth computational methods, structures of compounds and the mechanism of fluxional processes is explored. A couple of examples one each from inorganic and organic chemistry are shown below.

• Hydrides and dihydrogen complexes

Metal hydride complexes are well known to be excellent catalysts for hydrogenation reactions and have the potential to act as hydrogen storage materials. Dihydrogen complexes contain a hydrogen molecule that is essentially intact but acting as a ligand. We have an ongoing interest in these classes of compounds. We are interested in answering questions such as can we accurately determine the location of the hydrogen atoms in such molecules and interatomic distances? This can be difficult using crystallographic methods.

Hydride and dihydrogen complexes also often show interesting mechanisms of fluxionality, i.e., the hydrogen atoms interchange their positions within the complexes. NMR is ideally suited to revealing how these molecular reorientations take place.

Studying exchange in a polyhydride complex

• Photochromic organic compounds

Building on some high profile work led by the CSIRO, we have studied certain merocyanine molecules, similar to the type found in shade-changing photochromic lenses of spectacles. We have shown that a relatively rapid isomerization of different isomers can occur and that this process is catalyzed by acid.

Elucidating an acid catalysed isomerization process in a photomerocyanine compound at -80 °C.

We are currently investigating several other photochemically generated organic reactive intermediates with NMR spectroscopy at low temperatures.
References:
Yee, L. H.; Hanley, T.; Evans, R. A.; Davis, T. P.; Ball, G. E. "Photochromic Spirooxazines Functionalized with Oligomers: Investigation of Core-Oligomer Interactions and Photomerocyanine Isomer Interconversion Using NMR Spectroscopy and DFT" J. Org. Chem. 2010, 75, 2851-2860.
Evans, R.A; Hanley, T.L.; Skidmore, M.A.; Davis, T.P.; Such, G.K.; Yee, L.H; Ball, G.E.; Lewis, D.A. "Lubrication and Control of Nano-Mechanical Processes in Polymers." Nature Materials, 2005, 4, 193.

 
 amcrasto@gmail.com

http://newdrugapprovals.org/

DRUG APPROVALS BY DR ANTHONY MELVIN CRASTO

 
 amcrasto@gmail.com

http://newdrugapprovals.org/

DRUG APPROVALS BY DR ANTHONY MELVIN CRASTO