Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
Photoinduced electron-transfer within free base and zinc porphyrin containing poly(amide) dendrimers
Autore:
Rajesh, CS; Capitosti, GJ; Cramer, SJ; Modarelli, DA;
Indirizzi:
Univ Akron, Dept Chem, Akron, OH 44325 USA Univ Akron Akron OH USA 44325Univ Akron, Dept Chem, Akron, OH 44325 USA Univ Akron, Ctr Laser & Opt Spect, Knight Chem Lab, Akron, OH 44325 USA Univ Akron Akron OH USA 44325 Spect, Knight Chem Lab, Akron, OH 44325 USA
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 42, volume: 105, anno: 2001,
pagine: 10175 - 10188
SICI:
1520-6106(20011025)105:42<10175:PEWFBA>2.0.ZU;2-F
Fonte:
ISI
Lingua:
ENG
Soggetto:
PHOTOSYNTHETIC REACTION-CENTER; LIGHT-HARVESTING DENDRIMERS; TRANSITION-METAL COMPLEXES; BASKET-HANDLE PORPHYRINS; DOUBLE-RESONANCE NMR; ENERGY-TRANSFER; CHARGE SEPARATION; DENDRITIC MACROMOLECULES; SUPRAMOLECULAR ASSEMBLIES; ARTIFICIAL PHOTOSYNTHESIS;
Tipo documento:
Review
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
114
Recensione:
Indirizzi per estratti:
Indirizzo: Modarelli, DA Univ Akron, Dept Chem, Akron, OH 44325 USA Univ Akron AkronOH USA 44325 ept Chem, Akron, OH 44325 USA
Citazione:
C.S. Rajesh et al., "Photoinduced electron-transfer within free base and zinc porphyrin containing poly(amide) dendrimers", J PHYS CH B, 105(42), 2001, pp. 10175-10188

Abstract

The synthesis and photophysical characterization of a series of free base and zinc porphyrin containing, Newkome-type dendrimers terminated with anthraquinone groups (FbP-G(a)-AQ(n) and ZnP-G(a)-AQ(n)) and ethyl groups (FbP-G(a)-Et-n and ZnP-G(a)-Et-n) are described. These dendrimers were designed for use as mimics of the photosynthetic reaction center. Red-shifts in the absorption spectra, particularly in the anthraquinone-terminated series, were interpreted as resulting from backfolding of the dendrimer branches. Dendrimers FbP-G(a)-AQ(n) were shown to exhibit substantial quenching (58-75%)of the porphyrin fluorescence as measured against the analogous ethyl-terminated dendrimers (FbP-G(a)-Et-n) in steady-state fluorescence experiments. The zinc porphyrin containing dendrimers ZnP-G(a)-AQ(n) exhibited nearly complete quenching (96-99.5%) of the porphyrin fluorescence. An intramolecular electron-transfer mechanism is proposed for the substantial decrease in fluorescence in both series of dendrimers. Time-resolved fluorescence experiments for FbP-G(a)-AQ(n) were fit to 2-3 exponentials and indicated that multiple orientations of the porphyrin and anthraquinone groups contribute to the electron-transfer event. These results were in good agreement with the steady-state fluorescence results. From the time-resolved fluorescence data, the electron-transfer rate constants were calculated, indicating k(ET) values in the range of 3.77 x 10(7) s(-1) to 2.28 x 10(8) s(-1) that were dependent upon both dendrimer generation number and solvent. Similar experiments on ZnP-G(a)-AQ(n) also indicated that multiple zinc porphyrin anthraquinone conformations were likely responsible for the electron-transfer. Dramatic differences between the steady-state and time-resolved fluorescence data in the zinc porphyrin dendrimers were interpreted in terms of ligation of the terminal anthraquinone groups with the zinc porphyrin that results ineither a nonemissive state or an ultrafast electron-transfer.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 13/08/20 alle ore 02:12:18