title: Photochemical energy conversion in a helical oligoproline assembly.
abstract: A general method is described for constructing a helical oligoproline assembly having a spatially ordered array of functional sites protruding from a proline-II helix. Three different redox-active carboxylic acids were coupled to the side chain of cis-4-amino-L-proline. These redox modules were incorporated through solid-phase peptide synthesis into a 13-residue helical oligoproline assembly bearing in linear array a phenothiazine electron donor, a tris(bipyridine)ruthenium(II) chromophore, and an anthraquinone electron acceptor. Upon transient 460-nm irradiation in acetonitrile, this peptide triad formed with 53% efficiency an excited state containing a phenothiazine radical cation and an anthraquinone radical anion. This light-induced redox-separated state had a lifetime of 175 ns and stored 1.65 eV of energy.
authors.affiliation: Department of Chemistry, University of North Carolina, Chapel Hill 27599, USA.
authors.forename: D G
authors.initials: DG
authors.lastname: McCafferty
authors.forename: D A
authors.initials: DA
authors.lastname: Friesen
authors.forename: E
authors.initials: E
authors.lastname: Danielson
authors.forename: C G
authors.initials: CG
authors.lastname: Wall
authors.forename: M J
authors.initials: MJ
authors.lastname: Saderholm
authors.forename: B W
authors.initials: BW
authors.lastname: Erickson
authors.forename: T J
authors.initials: TJ
authors.lastname: Meyer
mesh_terms: D008958:Models, Molecular; D010084:Oxidation-Reduction; D010455:Peptides / Q000737:chemistry*; D010777:Photochemistry; D017433:Protein Structure, Secondary; D013057:Spectrum Analysis; D013997:Time Factors
chemical_list: D010455:Peptides; C011083:polyproline