HIGH MAGNETIC-FIELD AND MAGNETIC ISOTOPE EFFECTS ON LIFETIMES OF TRIPLET BIRADICALS CONSISTING OF 2 EQUIVALENT BENZOPHENONE KETYLS LINKED BY METHYLENE CHAINS

Authors
FUJIWARA Y AOKI T HAINO T FUKAZAWA Y TANIMOTO Y NAKAGAKI R TAKAHIRA O OKAZAKI M
Citation
Y. Fujiwara et al., HIGH MAGNETIC-FIELD AND MAGNETIC ISOTOPE EFFECTS ON LIFETIMES OF TRIPLET BIRADICALS CONSISTING OF 2 EQUIVALENT BENZOPHENONE KETYLS LINKED BY METHYLENE CHAINS, The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory, 101(37), 1997, pp. 6842-6849
Citations number
49
Categorie Soggetti
Chemistry Physical
Journal title
The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory → ACNP
ISSN journal
10895639
Volume
101
Issue
37
Year of publication
1997
Pages
6842 - 6849
Database
ISI
SICI code
1089-5639(1997)101:37<6842:HMAMIE>2.0.ZU;2-F
Abstract
External magnetic field and magnetic isotope effects on the lifetimes of several isotope-labeled triplet biradicals (BPH.-O-(CH2)(n)-O-BPH., n=8, 10, and 12) composed of two equivalent benzophenone ketyl radica ls (BPH(.)s) were studied by laser flash photolysis in magnetic fields up to 14 T. The biradical lifetimes increased with increasing a magne tic field below ca. 3 T and then slightly decreased at 4-14 T. Below 4 T, a large magnetic isotope effect on the biradical lifetimes was obs erved in C-13 isotope substitution at a benzylic carbon of BPH., where as no magnetic isotope effect was observed above 4 T. The magnetic iso tope effect in magnetic fields up to 4 T can be explained only by the spin-lattice relaxation mechanism due to the anisotropic hyperfine int eraction of the biradicals.