Photoinduced electron transfer involving eosin-tryptophan conjugates. Long-lived radical pair states for systems incorporating aromatic amino acid side chains
- Boston Univ., MA (United States)
The electron-transfer photochemistry of the covalent derivatives of the dye eosin, in which the xanthene dye is covalently attached to the amino acid L-tryptophan via the thiohydantoin derivative, the tryptophan dipeptide, and an ethyl ester derivative, has been investigated. The singlet excited state of the dye is significantly quenched on attachment of the aromatic amino acid residue. Dye triplet states are also intercepted through intramolecular interaction of excited dye and amino acid pendants. Flash photolysis experiments verify that this interaction involves electron transfer from the indole side chains of tryptophan. Rate constants for electron transfer are discussed in terms of the distance relationships for the eosin chromophore and aromatic redox sites on peptide derivatives, the pathway for [sigma]-[pi] through-bond interaction between redox sites, and the multiplicity and state of protonation for electron-transfer intermediates. Selected electron-transfer photoreactions were studied under conditions of binding of the peptide derivatives in a high molecular weight, water-soluble, globular polymer, poly(vinyl-2-pyrrolidinone). 28 refs., 4 figs., 1 tab.
- OSTI ID:
- 6980525
- Journal Information:
- Journal of Physical Chemistry; (United States), Vol. 98:28; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
AROMATICS
ELECTRON TRANSFER
PHOTOCHEMISTRY
TRYPTOPHAN
DERIVATIZATION
AMINO ACIDS
DYES
EOSIN
ESTERS
ORGANIC POLYMERS
PEPTIDES
PHOTOLYSIS
RADICALS
AZAARENES
AZOLES
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
CHEMISTRY
DECOMPOSITION
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROXY ACIDS
INDICATORS
INDOLES
ORGANIC ACIDS
ORGANIC BROMINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
POLYMERS
PROTEINS
PYRROLES
400500* - Photochemistry
400201 - Chemical & Physicochemical Properties