Quenching by oxygen of excited states of dyes on cotton investigated with diffuse reflectance laser flash photolysis and singlet oxygen detection

Diffuse reflectance laser flash photolysis was successfully employed to study the triplet states of dyes adsorbed on or chemically attached to cotton. This technique, together with the detection of singlet oxygen from dyes on cotton, made it possible to investigate the diffusion of oxygen in cotton fibres and the mobility of dyes adsorbed onto cotton. Absorption by the triplet states of aluminium phthalocyanine chloride and eosin and the phosphorescence of singlet oxygen produced by sensitisation with rose bengal was used to monitor oxygen diffusion and dye mobility by measuring differences in triplet lifetimes, singlet oxygen lifetimes and in signal intensities. It was found that swollen cotton allows diffusion of oxygen in the fibres. However, a noticeable effect on the triplet state of adsorbed aluminium phthalocyanine chloride is only observed if oxygen is removed or added by thorough evacuation or oxygenation of the samples over several days. Singlet oxygen was quenched dynamically by adsorbed dyes, which were found to be immobilised on the fibres, demonstrating that oxygen is mobile within the fibres at the molecular level.

[1]  N. Allen.  Photofading mechanisms of dyes in solution and polymer media , 2008 .

[2]  A. Datyner,et al.  Some Aspects of the Light Fastness of Reactive Azo‐dyes on Cellulose under Wet Conditions , 2008 .

[3]  D. Nicholson.  Using computer simulation to study the properties of molecules in micropores , 1996 .

[4]  F. Wilkinson,et al.  Photophysics of cyanine dyes on surfaces. A new emission from aggregates of 2,2′-cyanines adsorbed onto microcrystalline cellulose , 1996 .

[5]  G. S. Patel,et al.  Studies on swelling of cotton fibers in alkali metal hydroxides. IV. Influence of initial fiber properties and variations in fine structure on tensile behavior , 1995 .

[6]  A. Olea,et al.  Quenching of Excited States of Aromatic Hydrocarbons and their Derivatives by Oxygen , 1995 .

[7]  I. Khmelinskii,et al.  Photochemistry on Surfaces: Matrix Isolation Mechanisms Study of Interactions of Benzophenone Adsorbed on Microcrystalline Cellulose Investigated by Diffuse Reflectance and Luminescence Techniques , 1995 .

[8]  S. Marengo,et al.  Mesure du rendement d'oxygène singulet généré à partir de photosensibilisateurs tumoraux à base de naphtalocyanines , 1994 .

[9]  S. Costa,et al.  Photochemistry on surfaces: solvent–matrix effect on the swelling of cellulose. An emission and absorption study of adsorbed auramine O , 1993 .

[10]  Y. Okada,et al.  Oxidative and reductive fading of monochlorotriazinyl reactive dyes on cellulose under wet conditions , 1992 .

[11]  F. Wilkinson,et al.  Photochemistry on surfaces: fluorescence emission quantum yield evaluation of dyes adsorbed on microcrystalline cellulose , 1992 .

[12]  F. Wilkinson,et al.  PHOTOCHEMISTRY ON SURFACES: TRIPLET‐TRIPLET ENERGY TRANSFER ON MICROCRYSTALLINE CELLULOSE STUDIED BY DIFFUSE REFLECTANCE TRANSIENT ABSORPTION and EMISSION SPECTROSCOPY * , 1991 .

[13]  Y. Okada,et al.  Catalytic fading of vinylsulfonyl reactive dye mixtures on cellulose under wet conditions , 1990 .

[14]  Y. Okada,et al.  Photofading of vinylsulfonyl reactive dyes on cellulose under wet conditions , 1990 .

[15]  G. Kelly,et al.  Laser Flash Photolysis on Solid Surfaces , 1989 .

[16]  J. K. Thomas,et al.  Effect of humidity and temperature on photoinduced reactions in cellulose , 1988 .

[17]  F. Wilkinson.  Diffuse reflectance flash photolysis , 1986 .

[18]  F. Wilkinson,et al.  Detection of transient absorption in a dyed cotton fabric and in semiconductor powders by diffuse reflectance laser flash photolysis , 1985 .