UV-laser photochemistry: diffusion-controlled trapping of cyclic 1,3-diradicals by molecular oxygen. Conformational effects on triplet lifetimes
Journal Article
·
· J. Am. Chem. Soc.; (United States)
To explore the effects of methyl substitution at radical sites and ring size, 1,3-diradicals were generated from respective azoalkanes and oxygen trapping determined quantitatively. Molecular mechanics calculations suggest that in the lowest energy conformations the interorbital angles are ca. 0/sup 0/, 45/sup 0/, and 60/sup 0/ for the 1,3-diradicals, respectively. Thus, for the planar cyclopenta-1,3-diyl (planarity confirmed be ESR) intersystem crossing spin-orbital coupling should be most difficult, and hence it should have a relatively long triplet lifetime. In contrast, the rigid puckered bicyclo(2.2.1)hepta-2,7-diyl should be the most short-lived species of the three. The flexible twist-boat conformation of the cyclohexa-1,3-diyl possesses intermediate lifetime. Other than such conformational effects, it is difficult to rationalize the lifetimes of these rather similar 1,3-diradicals.
- Research Organization:
- Univ. of Wuerzburg/Am Hubland, Germany, F.R.
- OSTI ID:
- 5674265
- Journal Information:
- J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 109:24; ISSN JACSA
- Country of Publication:
- United States
- Language:
- English
Similar Records
UV-laser photochemistry of the azoalkane 1-phenyl-2,3-diazabicyclo(2. 2. 2)oct-2-ene: detection and lifetime determination of the triplet diradical 1-phenyl-1,4-cyclohexadiyl by time-resolved UV spectroscopy (flash photolysis) and by trapping with molecular oxygen
Large magnetic field effect on the decay rates of triplet hydrocarbon diradicals
Radical ion/triplet mechanism for sensitized valence photoisomerization of a norbornadiene
Journal Article
·
Tue Nov 24 23:00:00 EST 1987
· J. Am. Chem. Soc.; (United States)
·
OSTI ID:5674261
Large magnetic field effect on the decay rates of triplet hydrocarbon diradicals
Journal Article
·
Thu Jun 15 00:00:00 EDT 1989
· Journal of Physical Chemistry; (USA)
·
OSTI ID:6752268
Radical ion/triplet mechanism for sensitized valence photoisomerization of a norbornadiene
Journal Article
·
Thu Dec 31 23:00:00 EST 1981
· J. Phys. Chem.; (United States)
·
OSTI ID:5422855
Related Subjects
14 SOLAR ENERGY
140505 -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
ALKANES
AZO COMPOUNDS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISTRY
CONFIGURATION INTERACTION
CONFORMATIONAL CHANGES
DATA
DECOMPOSITION
DIFFUSION
ELEMENTS
EXPERIMENTAL DATA
HYDROCARBONS
INFORMATION
KINETICS
LIFETIME
MULTIPLETS
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN
PHOTOCHEMICAL REACTIONS
PHOTOCHEMISTRY
PHOTOLYSIS
RADICALS
REACTION INTERMEDIATES
REACTION KINETICS
TRIPLETS
140505 -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
ALKANES
AZO COMPOUNDS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISTRY
CONFIGURATION INTERACTION
CONFORMATIONAL CHANGES
DATA
DECOMPOSITION
DIFFUSION
ELEMENTS
EXPERIMENTAL DATA
HYDROCARBONS
INFORMATION
KINETICS
LIFETIME
MULTIPLETS
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN
PHOTOCHEMICAL REACTIONS
PHOTOCHEMISTRY
PHOTOLYSIS
RADICALS
REACTION INTERMEDIATES
REACTION KINETICS
TRIPLETS