The role of excited states in the photosensitized oxidation of substrates with dioxygen

Lang, Kamil; Wagnerová, D. M.; Brodilová, Jiřina

doi:10.1016/1010-6030(93)85078-m

Cited by 29 publications

(12 citation statements)

References 20 publications

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“…Metalloporphyrins and phthalocyanines have also been shown to be efficient visible light photosensitizers [166,191,192], with excitation occurring mainly via their ligand based transitions. The photosensitized oxidation of 4-chlorophenol by sulfonated aluminium and zinc phthalocyanines has been studied in oxygen(saturated aqueous solutions in the presence of the cationic tenside Septonex [193]. In the presence of oxygen the main product is p-benzoquinone.…”

Section: +mentioning

confidence: 99%

“…Both charge transfer quenching to produce phenoxyl radicals and 1,4-cycloaddition to give endoperoxides have been reported. With 4-chlorophenol, the main product of reaction with singlet oxygen is p-benzoquinone [329].…”

Section: Reactions Of Chlorophenols With Transient Intermediatesmentioning

confidence: 99%

“…A number of studies have been reported on the reaction of singlet molecular oxygen in solution with chlorophenols [50,114,122,124,[326][327][328][329][330]. Rates of reaction increase with pH [114], and show a pronounced substituent effect.…”

Section: Reactions Of Chlorophenols With Transient Intermediatesmentioning

confidence: 99%

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Kinetics and Mechanism of Photodegradation of Chlorophenols

Burrows¹,

Ernestova²,

Kemp³

et al. 1998

prog. rct. kin. mech.

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3. HOMOGENEOUS SENSITIZED SYSTEMS170 3·1 General background 170 3·1·1 Singlet oxygen as oxidant 171 3·2 Sensitized oxidation of chlorophenols by singlet oxygen 172 3·3 Homogeneous reactions of chlorophenols with metal complexes 176 4. PHOTOINDUCED DEGRADATION OF CHLOROPHENOLS 180 4·1 Free radical oxidation of chlorophenols 180 4·2 Free radical processes in semiconductor-photocatalysed degradation of chlorophenols 182 4·2·1 TiO 2 -mediated degradation of chlorophenols 183 4·3 Sensitization of chlorophenol degradation by supported catalysts 188 4·4 Radiation induced degradation of 2,4,6-trichlorophenol 191 5. REACTIONS OF CHLOROPHENOLS WITH TRANSIENT INTERMEDIATES 193 6. CONCLUSIONS 197 7. ACKNOWLEDGEMENTS 198 8. REFERENCES 198 ABSTRACTThe photodegradation of mono-, di-, tri-and pentachlorophenols in aqueous solution is surveyed from several viewpoints, namely kinetic and mechanistic, the nature of the reactive intermediates and final products, and the potential of photochemical means of treating water contaminated by chlorophenols. In direct photolysis, the roles of heterolytic and homolytic processes are considered, and the appearance of carbene, in addition to ionic and radical, intermediates noted. Sensitized photolysis deals with the roles of singlet oxygen and of a variety of metal complexes. The induced degradation of chlorophenols refers to the oxidation of chlorophenols by free radicals generated from photo-and radiolytic systems, particularly illuminated semiconductors such as titanium dioxide. The article finishes with an overview of the reactions of various types of reactive intermediates with chlorophenols. 1. dIonization potentials of 2-chlorophenol (8·66 eV) and 4-chlorophenol (8·94 eV) in organic solvents have been determined from charge transfer spectra with TCNE [51] e Values obtained for 4-chlorophenol for OH bond dissociation energies by this method, photoacoustic calorimetry [52], pulse radiolysis [53] and theoretical calculations [54] vary over the range 84·4-90·3 kcal mol -1 f Calculated in [50] g From [55] h n-butanol solution [56]

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Section: +mentioning

confidence: 99%

Section: Reactions Of Chlorophenols With Transient Intermediatesmentioning

confidence: 99%

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Kinetics and Mechanism of Photodegradation of Chlorophenols

Burrows¹,

Ernestova²,

Kemp³

et al. 1998

prog. rct. kin. mech.

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“…Non-transition M-PCs were known to be excellent photosensitizers because of their chemical stability and high absorbance in the 650–700 nm region [ 60 ]. In the presence of a photosensitizer, photooxidation progresses via singlet state oxygen [ 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 ]. M-PCs in the excited triplet state react with ground triplet state dioxygen.…”

Section: Resultsmentioning

confidence: 99%

Syntheses and Functional Properties of Phthalocyanines

2009

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Metal phthalocyanine tetrasulfonic acids, metal phthalocyanine octacarboxylic acids, metal octakis(hexyloxymethyl)phthalocyanines, and metal anthraquinocyanines have been synthesized. Then, zinc bis(1,4-didecylbenzo)-bis(3,4-pyrido)porphyrazines, the cyclotetramerization products of a 1:1 mixture of 3,6-didecylphthalonitrile and 3,4-dicyanopyridine, were synthesized. Futher, subphthalocyanine and its derivatives, with substituents such as thiobutyl and thiophenyl moieties were synthesized. Electrochemical measurements were performed on the abovementioned phthalocyanine derivatives and analogues in order to examine their electron transfer abilities and electrochemical reaction mechanisms in an organic solvent. Moreover, 1,4,8,11,15,18,22,25-octakis(thio-phenylmethyl)phthalocyanes were synthesized. The Q-bands of the latter compounds appeared in the near-infrared region. Furthermore, non-colored transparent films in the visible region can be produced.

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“…This is known as the Type II photosensitization mechanism. [11][12][13][14] However, one major drawback of phthalocyanines in PDT is their aggregation tendency, [15][16][17] which severely diminishes their photosensitizing ability. 2,10 However, the efficiency of the treatment is limited by their small extinction coefficient at the body therapeutic window (650-900 nm).…”

Section: Introductionmentioning

confidence: 99%

Effects of peripheral substitutions on the singlet oxygen quantum yields of monophthalocyaninato ytterbium(iii) complexes

Zhang

Cheng

et al. 2015

RSC Adv.

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A new monophthalocyaninato ytterbium(III) complex 5 with eight 3,5-di-t-butylphenoxyl substituents at peripheral positions is synthesized. X-ray structural analysis of 5$CHCl 3 $MeOH reveals that the Yb 3+ ion is seven-coordinate, surrounded by four nitrogen atoms from the phthalocyaninate dianion and three oxygen atoms from the anionic tripodal L OMeThe effects of substituents on the relative singlet oxygen ( 1 O 2 ) quantum yields of monophthalocyaninato ytterbium(III) complexes are investigated through comparison. It is found that the monophthalocyaninato ytterbium(III) complex has higher 1 O 2 quantum yield than its corresponding phthalocyaninate ligand. The introduction of a 3,5-di-t-butylphenoxy substituent on the microcycle can enhance the yield of singlet oxygen. Due to the heavy-atoms of both iodine and lanthanide ions, the ytterbium(III) complex 4 based on tert-butyl and iodine substituted phthalocyanine ligands has the highest 1 O 2 quantum yield (0.82).

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The role of excited states in the photosensitized oxidation of substrates with dioxygen

Cited by 29 publications

References 20 publications

Kinetics and Mechanism of Photodegradation of Chlorophenols

Kinetics and Mechanism of Photodegradation of Chlorophenols

Syntheses and Functional Properties of Phthalocyanines

Effects of peripheral substitutions on the singlet oxygen quantum yields of monophthalocyaninato ytterbium(iii) complexes

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