Pulse radiolysis study of pyridine-substituted quinoxalines

Pulse radiolysis study of pyridine-substituted quinoxalines The kinetics and spectral characteristics of the transients formed in the reactions of .OH, O.−, N. 3 and e−aq with the ligands 2,3-bis(pyridyl)quinoxaline (bpq), 2-(N-methyl),3-pyridyl quinoxaline (bpq+) and 6,7-dimethyl-2-(N-methyl)3-pyridyl quinoxaline (me2bpq+) were studied by pulse radiolysis. The second-order rate constant in the reaction of bpq measured at its λmax (365 nm) is twice (k = 9.8 × 109 dm3 mol−1 s−1) as compared to the charged ligands. The rates in the O.− reaction with all ligands are lower than observed in the .OH reaction. Further, the rates of azide and OH radicals are comparable. The rates of the reactions of hydrated electron with the ligands are in the range (1.5–2.4)×1010 dm3 mol−1 s−1. The transient absorption spectra recorded in the reactions of .OH, O.− and N. 3 with bpq are almost identical with an intense peak at 365 nm. The spectrum obtained in the reaction of .OH with me2 bpq+ has an absorption maximum at 390 nm whereas an additional peak at 675 nm was observed in its O.− reaction indicating a different reaction channel. In the azide reaction with me2bpq+, the intensity at λmax (390 nm) decreased with k = 2.5 × 104 s−1. A broad single peak in the region 375–390 nm was observed in the reaction of the hydrated electron with the ligands. The mechanistic details of the reactions are discussed. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Research on Chemical Intermediates Springer Journals

Pulse radiolysis study of pyridine-substituted quinoxalines

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Publisher
Springer Journals
Copyright
Copyright © 2005 by VSP
Subject
Chemistry; Inorganic Chemistry; Physical Chemistry; Catalysis
ISSN
0922-6168
eISSN
1568-5675
D.O.I.
10.1163/1568567053147002
Publisher site
See Article on Publisher Site

Abstract

The kinetics and spectral characteristics of the transients formed in the reactions of .OH, O.−, N. 3 and e−aq with the ligands 2,3-bis(pyridyl)quinoxaline (bpq), 2-(N-methyl),3-pyridyl quinoxaline (bpq+) and 6,7-dimethyl-2-(N-methyl)3-pyridyl quinoxaline (me2bpq+) were studied by pulse radiolysis. The second-order rate constant in the reaction of bpq measured at its λmax (365 nm) is twice (k = 9.8 × 109 dm3 mol−1 s−1) as compared to the charged ligands. The rates in the O.− reaction with all ligands are lower than observed in the .OH reaction. Further, the rates of azide and OH radicals are comparable. The rates of the reactions of hydrated electron with the ligands are in the range (1.5–2.4)×1010 dm3 mol−1 s−1. The transient absorption spectra recorded in the reactions of .OH, O.− and N. 3 with bpq are almost identical with an intense peak at 365 nm. The spectrum obtained in the reaction of .OH with me2 bpq+ has an absorption maximum at 390 nm whereas an additional peak at 675 nm was observed in its O.− reaction indicating a different reaction channel. In the azide reaction with me2bpq+, the intensity at λmax (390 nm) decreased with k = 2.5 × 104 s−1. A broad single peak in the region 375–390 nm was observed in the reaction of the hydrated electron with the ligands. The mechanistic details of the reactions are discussed.

Journal

Research on Chemical IntermediatesSpringer Journals

Published: Jan 1, 2005

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