Time-resolved EPR studies on the photochemical hydrogen abstraction reactions and the excited triplet states of 4-substituted pyridines

Journal Article · Thu Jan 24 04:00:00 EST 1991 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100155a051· OSTI ID:5760159

Tero-Kubota, Shozo; Akiyama, Kimio; Ikoma, Tadaaki; Ikegami, Yusaku ^[1]

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1. Tohoku Univ., Sendai (Japan)

Photochemical hydrogen abstraction reactions and the lowest excited triplet states taking part in the initial process have been investigated for several pyridine derivatives by using the time-resolved EPR method. The emissive CIDEP spectrum obtained from the laser photolysis of 4-acetylpyridine (1) in 2-propanol was assigned to the corresponding ketyl radical, proving initial hydrogen abstraction by the carbonyl group. In the cases of 4-cyano-(2) and 4-methoxycarbonyl-(3) pyridines, and 4-pyridinecarboxamide (4), enhanced absorptive CIDEP spectra due to the corresponding 1-hydropyridinyl radicals were observed, suggesting the preferential population to the lowest sublevel in the intersystem crossing. The triplet EPR and phosphorescence spectra observed at 77 K indicate that T{sub 1} of 1 is mainly the carbonyl n{pi}* state with a small contribution from the {pi}{pi}* state.

• OSTI ID: 5760159
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 95:2; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
AZINES
CHEMICAL REACTIONS
DATA
DECOMPOSITION
ELECTRON SPIN RESONANCE
ENERGY LEVELS
EXCITED STATES
EXPERIMENTAL DATA
HETEROCYCLIC COMPOUNDS
INFORMATION
MAGNETIC RESONANCE
MEASURING METHODS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PYRIDINES
RESONANCE