INVESTIGADORES
MARTINO Debora Marcela
congresos y reuniones científicas
Título:
FT-EPR Study of Alkyl Radicals Photo-generated from Alkylcobaloximes
Autor/es:
C. KIARIE; D.M. MARTINO; H. VAN WILLIGEN
Lugar:
Boston, USA, April 26
Reunión:
Conferencia; Fifth Annual Northeast Student Chemistry Research Conference; 2003
Resumen:
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Alkyl radicals photo generated from alkylcobaloximes were studied using Fourier
Transform Electron Paramagnetic Resonance (FT-EPR). Alkylcobaloximes
[RCo(dmgH)2(B)], are model compounds of vitamin B12 a coenzyme whose activity is attributed to
the presence of a CO-C bond. There is evidence that the radical pair (RP)
resulting from homolytic cleavage of this bond is important to the activity of
the coenzyme. The objective of the
present investigation was to contribute to the information on these RPs
through Chemically Induced Dynamic Electron Polarization (CIDEP) effects
observed in FT-EPR spectra of alkyl radicals generated upon excitation of
alkylcobaloximes at 355nm. It was
expected that the spectroscopic data would give an insight into the bond
dissociation process particularly the spin state of the dissociate state. CIDEP
patterns were strongly influenced by the nature of the solvent and axial
ligand. This is an indication that the excited state involved in the bond
cleavage reaction is and the evolution of the geminate radical pair depends
highly on the nature of the axial ligands and solvent-solute interactions.
Therefore depending on the identity of the solvent or axial base, the spin
polarization pattern may be dominated by a contribution from a singlet excited
state reaction channel or a triplet excited state reaction channel.
