Evaluation of EPR monitoring of singlet oxygen production using the photosensitizer chloroboron subphthalocyanine

2011 ◽  
Vol 15 (02) ◽  
pp. 118-121 ◽  
Author(s):  
Lawrence J. Berliner ◽  
Helmut Görner ◽  
Heinz-Peter Schuchmann
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Singlet Oxygen ◽  
Reaction System ◽  
Oxygen Production ◽  
Crucial Aspect ◽  
Singlet Molecular Oxygen ◽  
Radical Product ◽  
Paramagnetic Resonance ◽  
Boron Subphthalocyanine ◽  
Electron Paramagnetic

Singlet molecular oxygen produced in the presence of 2,2,6,6-tetramethyl-4-piperidone (TMPD) in 1,4-dioxan, by boron subphthalocyanine chloride as the sensitizer, was monitored by Electron Paramagnetic Resonance (EPR) via the oxidation of TMPD to the corresponding aminoxyl radical. This radical product is formed in low yields along the singlet oxygen pathway. A kinetic analysis of the process allows one to understand the reasons behind this, while affording more accurate quantitative insights into the mechanistic details. A crucial aspect of this reaction system, which explains the low aminoxyl radical yields along the singlet oxygen pathway, is the disappearance of the sensitizer triplet state in a reaction with TMPD, which has a rate constant of 1 × 109 M-1.s-1.

scholarly journals Singlet oxygen generation by higher fullerene-based colloids

2010 ◽  
Vol 75 (7) ◽  
pp. 965-973 ◽  
Author(s):  
Svetlana Jovanovic ◽  
Zoran Markovic ◽  
Duska Kleut ◽  
Vladimir Trajkovic ◽  
Branka Babic-Stojic ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Singlet Oxygen ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Resonance Spectroscopy ◽  
Paramagnetic Resonance ◽  
Oxygen Generation ◽  
Force Microscopy ◽  
Water Based ◽  
Average Size ◽  
Electron Paramagnetic

In this paper, the results of the synthesis and characterization of higher fullerene-based colloids is presented. The generation of singlet oxygen 1O2 (1?g) by fullerene water-based colloids (nC60, nC70 and nC84) was investigated. It was found by electron paramagnetic resonance spectroscopy that the generation of singlet oxygen was the highest by the nC84 colloid. The amplitude of the electron paramagnetic resonance (EPR) signal was two orders of magnitude higher than the amplitude of the EPR signals which originated from nC60 and nC70. The surface morphology and the structure of the particles of the water-based colloids were investigated by atomic force microscopy (AFM). The AFM study showed that the average size of the nC60, nC70 and nC84 were 200 nm, 80 nm and 70 nm, respectively. In addition, the particle size distribution of the nC60, nC70 and nC84 colloids was determined by dynamic light scattering (DLS) measurements.

An electron paramagnetic resonance spectroscopic investigation of hydroxyl-radical attack on allyl alcohol

1967 ◽  
Vol 45 (6) ◽  
pp. 649-654 ◽  
Author(s):  
P. Smith ◽  
P. B. Wood
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Hydroxyl Radical ◽  
Allyl Alcohol ◽  
Reaction System ◽  
Alcohol Concentration ◽  
Paramagnetic Resonance ◽  
Relative Contribution ◽  
Aqueous Flow ◽  
Electron Paramagnetic ◽  
Radical Attack

Allyl alcohol has been subjected to hydroxyl-radical attack at 25 ± 2 °C within the cavity of an X-band electron paramagnetic resonance (e.p.r.) spectrometer by use of an aqueous flow system in which the hydroxyl radicals were generated by mixing solutions of titanous chloride and hydrogen peroxide containing sulfuric acid. The reaction conditions were varied over a considerable range. At low allyl alcohol concentrations the e.p.r. absorption observed arose chiefly from the two possible addition products CH2(OH)CHCH2OH, I, and ·CH2CH(OH)CH2OH, II, present in roughly equal steady-state molar concentrations; a relatively weak signal from the hydrogen-atom abstraction product CH2:CHCHOH, III, was also observed. As the allyl alcohol concentration was raised, the relative contribution from I and II fell while that from the products of the addition of I and II to allyl alcohol became increasingly evident. These results considerably extend and clarify those previously reported for allyl alcohol by earlier workers using this reaction system.

Electron-paramagnetic resonance and photoluminescence study of Si nanocrystals-photosensitizers of singlet oxygen molecules

2006 ◽  
Vol 352 (9-20) ◽  
pp. 1156-1159 ◽  
Author(s):  
E.A. Konstantinova ◽  
V.A. Demin ◽  
A.S. Vorontzov ◽  
Yu. V. Ryabchikov ◽  
I.A. Belogorokhov ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Singlet Oxygen ◽  
Paramagnetic Resonance ◽  
Photoluminescence Study ◽  
Si Nanocrystals ◽  
Electron Paramagnetic
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