Photosensitized transformation of 4-chlorophenol in the presence of aggregated and non-aggregated metallophthalocyanines

Abstract The photosensitizing properties of various water-soluble zinc and aluminum phthalocyanines towards the phototransformation of 4-chlorophenol (4-Cp) are presented. The complexes studied are the zinc (ZnPcS 4 ) and aluminum (AlPcS 4 ) tetra-sulfophthalocyanines; the zinc and aluminum complexes containing a mixture of differently substituted sulfophthalocyanines (represented as zinc (ZnPcS mix ) and aluminum (AlPcS mix ), respectively); the zinc (ZnOCPc) and aluminum (AlOCPc) octacarboxy phthalocyanines. The AlPcS mix and ZnPcS mix complexes showed the best photocatalytic activity towards the transformation of 4-Cp. The values of singlet oxygen quantum yields of the sensitizers were obtained, and it was found that the rates of 4-Cp photooxidation, in general, follow the efficiency of singlet oxygen photosensitization by the phthalocyanine complexes. At 4-Cp concentration below 10 −4  mol l −1 , photooxidation by singlet oxygen is the dominating mechanism of substrate photodegradation, while at 4-Cp concentration above 10 −3  mol l −1 the role of Type I mechanism increases. Kinetic analysis indicates that interaction of 4-Cp with singlet oxygen mainly results in “physical” quenching with ( k q + k r )=(13.5±3)×10 8  mol −1  l s −1 and k r =(2.7±0.3)×10 8  mol −1  l s −1 for the phenolate form of 4-Cp, which significantly limits the rates and quantum yields of 4-Cp photooxidation.

[1]  L. Grossweiner,et al.  Singlet oxygen generation by photodynamic agents , 1997 .

[2]  E. Papaconstantinou,et al.  On the mechanism of photocatalytic degradation of chlorinated phenols to CO2 and HCl by polyoxometalates , 1996 .

[3]  K. Sakamoto,et al.  Synthesis and electron transfer property of phthalocyanine derivatives , 1997 .

[4]  M. Nowakowska,et al.  Photosensitized dechlorination of polychlorinated phenols 2. Photoinduced by poly(sodium styrenesulphonate-co-N-vinylcarbazole) dechlorination of pentachlorophenol in water , 1996 .

[5]  O. Kaliya,et al.  Catalysis and Photocatalysis by Phthalocyanines for Technology, Ecology and Medicine , 1999 .

[6]  N. Serpone,et al.  Kinetics studies in heterogeneous photocatalysis. I. Photocatalytic degradation of chlorinated phenols in aerated aqueous solutions over titania supported on a glass matrix , 1988 .

[7]  B. N. Toleutaev,et al.  Rise and decay kinetics of photosensitized singlet oxygen luminescence in water. Measurements with nanosecond time-correlated single photon counting technique , 1989 .

[8]  Paul G Tratnyek,et al.  Oxidation of substituted phenols in the environment: a QSAR analysis of rate constants for reaction with singlet oxygen , 1991 .

[9]  E. Papaconstantinou,et al.  Photocatalytic degradation of phenol and p-cresol by polyoxotungstates. mechanistic implications , 1996 .

[10]  A. Mills,et al.  PHOTOMINERALIZATION OF 4-CHLOROPHENOL SENSITIZED BY TITANIUM-DIOXIDE - A STUDY OF THE INITIAL KINETICS OF CARBON-DIOXIDE PHOTOGENERATION , 1993 .

[11]  Steffen Hackbarth,et al.  Singlet Oxygen Quantum Yields of Different Photosensitizers in Polar Solvents and Micellar Solutions , 1998 .

[12]  D. Phillips,et al.  Comparison of the photophysics of an aggregating and non-aggregating aluminium phthalocyanine system incorporated into unilamellar vesicles , 1996 .

[13]  M. Nowakowska,et al.  Photosensitized dechlorination of polychlorinated phenols 1. Carbazole-photosensitized dechlorination of pentachlorophenol , 1995 .

[14]  K. Lang,et al.  The role of excited states in the photosensitized oxidation of substrates with dioxygen , 1993 .

[15]  D. Wöhrle,et al.  Photo-oxidation of phenol and monochlorophenols in oxygen-saturated aqueous solutions by different photosensitizers , 1997 .

[16]  L. S. Ernestova,et al.  Photochemical transformation of polychlorinated phenols , 1997 .

[17]  E. Lipczynska-Kochany,et al.  Flash photolysis/HPLC method for studying the sequence of photochemical reactions: applications to 4-chlorophenol in aerated aqueous solution , 1991 .

[18]  R. H. Davies,et al.  Photomineralisation of 4-chlorophenol sensitised by titanium dioxide: a study of the intermediates , 1993 .

[19]  Christopher S. Foote,et al.  CHEMISTRY OF SINGLET OXYGEN—XXVI. PHOTOOXYGENATION OF PHENOLSy † , 1978 .

[20]  Daryle H. Busch,et al.  Complexes Derived from Strong Field Ligands. XIX. Magnetic Properties of Transition Metal Derivatives of 4,4',4",4'''-Tetrasulfophthalocyanine , 1965 .

[21]  B. Meunier,et al.  CO2 as the Ultimate Degradation Product in the H2O2 Oxidation of 2,4,6-Trichlorophenol Catalyzed by Iron Tetrasulfophthalocyanine , 1996 .

[22]  R. Niessner,et al.  Formation of Polychlorinated Dibenzo-p-dioxins and Polychlorinated Dibenzofurans during the Photolysis of Pentachlorophenol-Containing Water. , 1994, Environmental Science and Technology.

[23]  B. Meunier,et al.  Oxidation of Pollutants Catalyzed by Metallophthalocyanines , 1997 .

[24]  J. E. Lier,et al.  Sulfonated Phthalocyanines: Photophysical Properties, in vitro Cell Uptake and Structure-activity Relationships , 1998 .

[25]  Martin Gouterman,et al.  Effects of ligands, solvent, and variable sulfonation on dimer formation of aluminum and zinc phthalocyaninesulfonates , 1991 .

[26]  V. Iliev,et al.  Effect of metal phthalocyanine complex aggregation on the catalytic and photocatalytic oxidation of sulfur containing compounds , 1999 .

[27]  N. García,et al.  Sensitized photo-oxidation of dihydroxybenzenes and chlorinated derivatives. A kinetic study , 1991 .

[28]  Eugeny A. Lukyanets,et al.  Phthalocyanines as Photosensitizers in the Photodynamic Therapy of Cancer , 1999 .

[29]  D. Phillips,et al.  Preparative, analytical and fluorescence spectroscopic studies of sulphonated aluminium phthalocyanine photosensitizers. , 1991, Journal of photochemistry and photobiology. B, Biology.

[30]  F. Wilkinson,et al.  A nanosecond laser flash photolysis study of aqueous 4-chlorophenol , 1996 .