Photosensitized electron-transfer reactions and H sub 2 evolution in organized microheterogeneous environments: Separation of ground-state xanthene-bipyridinium complexes by SiO sub 2 colloids

Journal Article · Thu Apr 05 00:00:00 EDT 1990 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100370a064· OSTI ID:6634819

Willner, I; Eichen, Y; Joselevich, E ^[1]

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1. Hebrew Univ. of Jerusalem (Israel)

Rose bengal, Rb{sup 2{minus}}, forms a ground-state complex with N,N{prime}-dimethyl-4,4{prime}-bipyridinium, MV{sup 2+}, with an association constant of K{sub a} = 11,000 {plus minus} 1,100 M{sup {minus}1}. Static electron-transfer quenching of excited Rb{sup 2{minus}} occurs in the complex structure, but charge separation is eliminated due to rapid back electron transfer in the encounter cage complex of photoproducts. In the presence of added SiO{sub 2} colloid particles the (Rb{sup 2{minus}}{hor ellipsis}MV{sup 2+}) complex is separated through the selective association of MV{sup 2+} to the negatively charged colloid interface. Upon illumination of a solution that includes Rb{sup 2{minus}}, MV{sup 2+}, and the sacrificial electron donor triethanolamine (TEOA) in the presence of SiO{sub 2} colloid, the photosensitized formation of MV{sup {sm bullet}+} proceeds effectively, {phi} = 0.1. Mechanistic studies show that the SiO{sub 2} colloid controls the photoinduced electron-transfer process, and stabilization of the intermediate photoproducts against the back-electron-transfer process is achieved.

• OSTI ID: 6634819
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 94:7; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
AMINES
AMMONIUM COMPOUNDS
AZINES
CHALCOGENIDES
CHEMICAL REACTIONS
DATA
DATA ANALYSIS
ELECTRON TRANSFER
EXPERIMENTAL DATA
HETEROCYCLIC COMPOUNDS
HETEROGENEOUS EFFECTS
INFORMATION
MEASURING INSTRUMENTS
MEASURING METHODS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PYRIDINES
PYRIDINIUM COMPOUNDS
QUATERNARY COMPOUNDS
SILICON COMPOUNDS
SILICON OXIDES