Far ultraviolet induced decomposition of thymine in deaerated and aerated aqueous solutions

1986 ◽  
Vol 64 (12) ◽  
pp. 2297-2300 ◽  
Author(s):  
Bunsho Ohtani ◽  
Hiroshi Nagasaki ◽  
Sei-Ichi Nishimoto ◽  
Koichi Sakano ◽  
Tsutomu Kagiya
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Ultraviolet Light ◽  
Quantum Yields ◽  
Near Ultraviolet ◽  
Induced Decomposition ◽  
Far Ultraviolet ◽  
Cis And Trans

Thymine in aqueous solution was decomposed with quantum yields of 0.3 and 0.4 under N2-saturated and aerated conditions by far-ultraviolet light (> 180 nm, far-uv), and quantum yields of 2 × 10−4 and 3 × 10−4 by near-ultraviolet light (> 220 nm, near-uv), respectively. The main photolytic products by far-uv were 5,6-dihydrothymine (DHT) (selectivity: S (DHT) = 0.2) and 5-hydroxymethyluracil (HMU) (S(HMU) = 0.1) under N2-saturated conditions, cis- and trans-5,6-Dihydroxy-5,6-dihydrothymine (TG), 6(5)-hydroperoxy-5(6)-hydroxy-5,6-dihydrothymine (HTP) (S(TG) + S (HTP) = 0.2), and N1 -formyl-N2-pyruvylurea (FPU) (S(FPU) = 0.4) were obtained under aerated conditions. These products were attributed to the reactions of thymine with the H and OH produced by photolysis of water.

Photochemistry of the cis- and trans-Dichlorobisethylenediamine Chromium(III) Cations in Acidic Aqueous Solutions. Observation of a Stereochemical Change in Photoaquation

1971 ◽  
Vol 49 (9) ◽  
pp. 1524-1528 ◽  
Author(s):  
A. D. Kirk ◽  
K. C. Moss ◽  
J. G. Valentin
Keyword(s):  
Aqueous Solution ◽  
Quantum Yield ◽  
Aqueous Solutions ◽  
Trans Isomer ◽  
Ligand Field ◽  
Acidic Aqueous Solution ◽  
Ethylenediamine Complex ◽  
Cis And Trans ◽  
Cis Isomer

The photoreactions of cis- and trans-[CrCl2(en)2]+ have been investigated in acidic aqueous solution at pH 3 and 0 °C. On photolysis in the ligand field bands the cis isomer was found to undergo mainly ethylenediamine aquation, apparently to a thermally unstable monodentate protonated ethylenediamine complex, with a quantum yield of 0.13. In addition chloride aquation occurred with[Formula: see text]. In contrast, the trans isomer underwent exclusive chloride aquation with quantum yield 0.32. The results are qualitatively, but not quantitatively, in agreement with predictions of Adamson's empirical rules. It was found that for trans-[CrCl2(en)2]+ photolysis, the reaction product [CrCl(H2O)(en)2]2+ was produced at least 70% in the cis configuration.

Study on the photostability of water-soluble Zn(II) and Al(III) phthalocyanines in aqueous solution

2010 ◽  
Vol 14 (11) ◽  
pp. 968-974 ◽  
Author(s):  
Nina A. Kuznetsova ◽  
Dmitry A. Makarov ◽  
Olga A. Yuzhakova ◽  
Ludmila I. Solovieva ◽  
Oleg L. Kaliya
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Singlet Oxygen ◽  
Narrow Range ◽  
Water Soluble ◽  
Zinc Phthalocyanine ◽  
Quantum Yields ◽  
Type Ii ◽  
Positively Charged ◽  
Dye Structure

The photodegradation of a series of water-soluble Zn(II) and Al(III) phthalocyanines has been studied in aerobic aqueous solutions. The photobleaching quantum yields of zinc phthalocyanine derivatives range from 2.2 × 10-4 for octacarboxy- to 1.5 × 10-5 for ZnPc , bearing 16 positively charged groups on periphery. Their aluminum counterparts are more photostable and photobleach with quantum yields in the narrow range (0.75 ÷ 2 × 10-6). The pH dependences of the photobleaching quantum yields for aluminum phthalocyanines show enhanced photodegradation for molecules with deprotonated axial H2O ligand. Some aspects of the mechanism of dyes photodegradation were studied and discussed. It was found that contribution to photooxidation of type II pathways depends upon a particular dye structure. Thus, no contribution of singlet oxygen to the photooxidation of cationic phthalocyanines has been found, even though singlet oxygen is involved in the photodegradation of negatively charged phthalocyanines.

Photolysis of Imidazolinone Herbicides in Aqueous Solution and on Soil

Weed Science ◽  
1992 ◽  
Vol 40 (1) ◽  
pp. 143-148 ◽  
Author(s):  
William S. Curran ◽  
Mark M. Loux ◽  
Rex A. Liebl ◽  
F. William Simmons
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Ultraviolet Light ◽  
Field Capacity ◽  
Silty Clay ◽  
Clay Loam ◽  
Silty Clay Loam ◽  
Moist Sand ◽  
Photolytic Degradation ◽  
Imidazolinone Herbicides

The photolytic degradation of several imidazolinone herbicides in solution and on soil was investigated. Ultraviolet light caused 100% degradation of imazaquin, imazethapyr, and imazapyr, and 87 and 8% degradation of imazamethabenz and atrazine in aqueous solutions, respectively, after 48 h. The order of susceptibility to photolysis in decreasing order was imazaquin = imazethapyr > imazapyr > imazamethabenz > atrazine. In soil Studies, 45% of imazaquin and 52% of imazethapyr dissipated from moist sand after 48 h of exposure. Herbicide dissipation on air-dry sand and on field capacity and air-dry silty clay loam was less than 10% in most instances. Atrazine photolysis was not detected. This research indicates that photolysis of imidazolinone herbicides in solution is rapid. Photolysis on soil occurs readily on coarse-textured wet soils probably due to greater availability of the herbicide for photochemical alteration.

Influence of Environment on the Photooxidation of Tryptophan with the Carcinogenic Hydrocarbon 3,4-Benzopyrene in Aqueous Solutions of Soap, Caffeine, and Urea

1973 ◽  
Vol 28 (7-8) ◽  
pp. 390-396 ◽  
Author(s):  
Günter Reske ◽  
Horst Bauer
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Sodium Dodecylsulfate ◽  
Quantum Yields ◽  
Solvation State ◽  
Solvent Dependence ◽  
Induced Dipole ◽  
Carcinogenic Hydrocarbon ◽  
The Difference ◽  
Photooxidation Of Tryptophan

Abstract The solvent dependence of the photooxidation of tryptophan and 3,4-benzopyrene in aqueous solutions was studied by quantum yield measurements. When the hydrocarbon is dissolved in aqueous solution of caffeine, the quantum yields indicate a 3,4-benzopyrene photosensitized trypto­ phan oxidation instead of a photocooxidation, which is indicated in aqueous solution of sodium dodecylsulfate. The same photosensitized oxidation as in caffeine solution is observed, when urea (6 ᴍ) is added to the soap solution, while the fluorescence and absorption spectra indicate no change in the solvation state of the hydrocarbon, comparable to the change from hydrophobic solubilization by the detergent to dipole - induced dipole complex solubilization by caffeine. It is concluded that the difference in the reaction pathways is caused by different solvation states of the excited or reacting oxygen. In the discussion of the results it is referred to reactions of inhibitors.

RADIATION-INDUCED DECOMPOSITION AND POLYMERIZATION OF POLYVINYL ALCOHOL IN AQUEOUS SOLUTIONS

2013 ◽  
Vol 12 (7) ◽  
pp. 1323-1328 ◽  
Author(s):  
Lujun Chen ◽  
Weihua Sun ◽  
Jinping Tian ◽  
Jianlong Wang ◽  
Shijun He
Keyword(s):  
Polyvinyl Alcohol ◽  
Aqueous Solutions ◽  
Radiation Induced ◽  
Induced Decomposition
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