Reactions in microemulsions. IV. Kinetics of chlorophyll sensitized photoreduction of methyl red and crystal violet by ascorbate

Journal Article · Thu Apr 05 04:00:00 EST 1979 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100470a009· OSTI ID:6232523

Jones, C E; Jones, C A; Mackay, R A

The photoreduction of adsorbed dye (methyl red and crystal violet) sensitized by chlorophyll a in an anionic mineral oil in water microemulsion system has been investigated. The 100-A microdroplets occupy 40% of the total volume, and at the pigment concentrations employed (less than or equal to 10 ..mu..M) there is on the average less than one chlorophyll molecule per drop. Using ascorbate as the water-soluble reducing agent, the reaction exhibits a pseudo-first-order dependence on crystal violet, but a pseudo-zero-order dependence on methyl red. The chlorophyll fluorescence is quenched by methyl red, but not by crystal violet. The effect of sensitizer and of ascorbate concentration and light intensity on the quantum yield has also been examined. From the results of these and auxiliary studies, a reaction mechanism is proposed which involves the formation of a chlorophyll-dye triplet exciplex rather than the initial formation of an oxidized or reduced pigment species. Based on this scheme, a number of rate constants have been estimated.

• Research Organization: Drexel Univ., Philadelphia, PA
• OSTI ID: 6232523
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 83:7; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
AMINES
AMINO ACIDS
ASCORBIC ACID
AZO COMPOUNDS
AZO DYES
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
CHEMISTRY
CHLOROPHYLL
COLLOIDS
DATA
DATA FORMS
DISPERSIONS
DYES
EMULSIONS
EXPERIMENTAL DATA
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INDICATORS
INFORMATION
ISOLATED VALUES
METHYL RED
METHYL VIOLET
MICROEMULSIONS
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMISTRY
PHYTOCHROMES
PIGMENTS
PORPHYRINS
REAGENTS
REDUCTION
SALTS
SENSITIZERS
TRIPHENYLMETHANE DYES
VITAMINS