Ground- and excited-state proton transfers in reversed micelles. Polarity restrictions and isotope effects
Ground- and excited-state proton transfers have been investigated with 8-hydroxy-1,3,6-pyrenetrisulfonate, POH, in sodium bis(2-ethylhexyl) sulfosuccinate, AOT, reversed micelle solubilized water pools in isooctane. Since POH is a much stronger acid in the singlet excited state, (POH)*, than in the ground state (pK/sub a/ = 7.2, pK/sub a/* = 0.5), excitation of POH by 1-5-mJ, 8-ns, 353-nm laser pulses, at pH values such that pK/sub a/* < pH < pK/sub a/, results in the dissociation of POH, governed by k/sub off/*. PO/sup -/ reprotonation rate, K/sub on/ values, have been determined by laser flash photolysis. In reversed micelles k/sub on/ values were found to depend on the water-to-AOT ratio(w values). Deuterium solvent isotope effects of 1.3 and 2.2 have been determined for k/sub on//k/sub on/(D/sub 2/O) in w = 33 and 12 AOT solubilized reversed micelles in isooctane. Combining these values with pK/sub a/ of POH led to isotope effects of 7.8 and 8.4 on k/sub off/ in the corresponding solutions. Steady-state and subnanosecond time-resolved fluorescence measurements have been utilized for assessing POH excited-state deprotonation, governed by k/sub off/*(D/sub 2/O), and reprotonation, governed by k/sub on/*(D/sub 2/O), in pure D/sub 2/O and in AOT entrapped water and AOT-d entrapped D/sub 2/O pools in isooctane. 51 references, 10 figures, 6 tables.
- Research Organization:
- Clarkson College of Tech., Postdam, NY
- OSTI ID:
- 5048243
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 89:11
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
MICELLAR SYSTEMS
CHARGE STATES
CHEMICAL REACTION KINETICS
ISOTOPE EFFECTS
PYRENE
HYDROGEN TRANSFER
SUCCINIC ACID
SULFONATES
DISSOCIATION
EXCITED STATES
EXPERIMENTAL DATA
FLUORESCENCE SPECTROSCOPY
HEAVY WATER
LASERS
OCTANE
PH VALUE
PHOTOLYSIS
WATER
ALKANES
AROMATICS
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
CONDENSED AROMATICS
DATA
DECOMPOSITION
DICARBOXYLIC ACIDS
EMISSION SPECTROSCOPY
ENERGY LEVELS
HYDROCARBONS
HYDROGEN COMPOUNDS
INFORMATION
KINETICS
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
REACTION KINETICS
SPECTROSCOPY
400301* - Organic Chemistry- Chemical & Physicochemical Properties- (-1987)
400302 - Organic Chemistry- Isotope Effects- (-1987)