Picosecond and nanosecond studies of the photoreduction of benzophenone by 1,4-diazabicyclo(2. 2. 2)octane: Characterization of the transient

Journal Article · Thu May 31 00:00:00 EDT 1990 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100374a036· OSTI ID:6428266

Devadoss, C; Fessenden, R W ^[1]

---

1. Univ. of Notre Dame, IN (USA)

The transient that is produced in the quenching of triplet benzophenone by 1,4-diazabicyclo(2.2.2)octane (DABCO) has been examined by use of nano- and picosecond laser photolysis. The initial step in all solvents, both polar and nonpolar, is electron transfer to form a triplet contact ion pair. In nonpolar solvents, the ion pair remains in this form until it decays. For polar solvents, the spectra change somewhat over the first 100 ps showing that the solvation changes and the ion pair becomes solvent separated. The lifetime of the ion pair varies greatly with the solvent. In saturated hydrocarbons it is about 80 ps. Nonpolar solvents with either {pi} electrons or a lone pair of electrons stabilize the ion pair on the nanosecond to microsecond time scale. A small amount of alcohol in benzene also stabilizes the ion pair by hydrogen bonding. A shift in the peak position with time toward the blue accompanies the formation of hydrogen bonds in this case.

• OSTI ID: 6428266
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 94:11; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
BENZOPHENONE
CHEMICAL REACTIONS
DATA
DATA ANALYSIS
EXPERIMENTAL DATA
INFORMATION
KETONES
MEASURING INSTRUMENTS
MEASURING METHODS
NUMERICAL DATA
ORGANIC COMPOUNDS
PHOTOCHEMICAL REACTIONS
REACTION INTERMEDIATES
REDUCTION
TRANSIENTS