Extinction coefficient and recombination rate of benzyl radicals. I. Photolysis of sodium phenylacetate

Meiggs, Theodore O.; Grossweiner, Leonard I.; Miller, Sidney I.

doi:10.1021/ja00778a008

Cited by 50 publications

(25 citation statements)

References 2 publications

(2 reference statements)

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“…From the value f BR = 0.26, and the absorbance profiles shown in Fig. 6, if we assume that the molar decadic absorption coefficients of free and adsorbed BP triplet states are the same at 320 nm (e 320 = 11800 M M )1 cm )1 ) (38), the estimated absorption coefficient of the chemisorbed benzyl radical at 320 nm is 2200 M M )1 cm )1 , in good agreement with the value reported by Meiggs et al (39) for the free radical in methanol.…”

Section: Lfp Experimentssupporting

confidence: 87%

Generation of Chemisorbed Benzyl Radicals on Silica Nanoparticles

Arce

Rosso

Oliveira

et al. 2010

Photochem & Photobiology

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Functionalized silica nanoparticles (NP) were obtained by esterification of the silanol groups of fumed silica nanoparticles with benzyl alcohol. These particles were characterized by Fourier transform infrared spectroscopy, (13)C and (29)Si NMR spectroscopy, thermogravimetry, total organic carbon, Brunauer-Emmett-Teller analysis, UV-visible spectroscopy, and transmission electron microscopy. NP suspensions in water/acetonitrile mixtures were used as quenchers of benzophenone (BP) phosphorescence in time-resolved experiments at the excitation wavelength of 266 nm. The phosphorescence signals obtained in the presence of the nanoparticles were fitted to biexponential decays. Both decays were accelerated in the presence of increasing amounts of NP. A model, including the reversible adsorption of BP on the NP, which was supported by computer simulations accounts for the observed results. Laser flash-photolysis experiments with excitation at 266 nm of NP suspensions in water/acetonitrile in the presence of BP generated benzyl radicals that were attached to the silica surface. These radicals were detected at their absorption maxima (320 nm) by transient optical techniques.

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Section: Lfp Experimentssupporting

confidence: 87%

Generation of Chemisorbed Benzyl Radicals on Silica Nanoparticles

Arce

Rosso

Oliveira

et al. 2010

Photochem & Photobiology

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“…Phenylacetic acid and related compounds are light unstable (Givens and Levi, 1979;Meiggs et a[., 1972;Eppling and Lopes, 1977), typically undergoing photochemical decarboxylation via intermediate benzylic radicals. The non-steroidal anti-inflammatory arylalkanoic acids, advantageously used in the treatment of wide variety of inflammatory diseases, are structurally related t o phenylacetic acid and might exhibit, in principle, the same type of photochemical reactivity.…”

Section: Introductionmentioning

confidence: 99%

PHOTOLYTIC DEGRADATION OF IBUPROFEN. TOXICITY OF THE ISOLATED PHOTOPRODUCTS ON FIBROBLASTS and ERYTHROCYTES

Castell

Gomez-L.

Miranda

et al. 1987

Photochem & Photobiology

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The photodegradation of Ibuprofen, a widely used non‐steroidal anti‐inflammatory drug (NSAID), was examined. Several photoproducts (I‐VI) were isolated and identified on the basis of their IR‐1H‐NMR‐ and 13C‐NMR‐ spectra. The chemical structures were confirmed by unambiguous alternative synthesis from available reagents. The most significant primary photochemical process was the cleavage of the C‐C bond a to the carboxy group. Subsequent secondary processes (hydrogen abstraction, dimerization, incorporation of methanol, or reaction with oxygen) might account for the formation of the different photoproducts. The cytotoxic effects were assayed using the red‐blood cell lysis test and the enzyme leakage (LDH and GOT) from cultured fibroblasts. Compound V [l‐(4 isobutylphenyl)‐ethanol] was found to be toxic for both system at concentrations greater than 1 mM while compound IV [l‐(4 isobutylphenyl acetophenone)] was toxic for fibroblasts but not for erythrocytes at the same concentration. Ibuprofen and the other photocompounds were apparently non‐toxic. The significance of these results is discussed in connection with the possible in vivo phototoxicity of Ibuprofen.

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“…For instance, in cyclohexane solvent t R = 12,000 M -~ cm-' [24] and eR =9000 M-I cm-' [19] have been reported. For water as solvent, eR=9000 [20], 8520 [25], 5500 [21d] and 2000 M-I cm-I [26] were found, and in alcohols the values of &R=2000 [26] and 1100 M -~ cm-' [27] were determined. Less well comparable are the low-temperature data obtained from glasses (eR = 19,000 [28], 18,000 [29] and 12,000 [29]) and the very large gase-phase result of eR 5 lo6 M-' Cm-l [30].…”

mentioning

confidence: 99%

Absorption Spectra and Termination Kinetics of Transient Free Radicals in Solution Observed by UV./VIS. Spectroscopy with modulated excitation

Huggenberger

Fischer

1981

Helvetica Chimica Acta

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SummaryFree radicals are generated in liquid solutions by harmonically modulated photolysis of suitable substrates. Harmonic analysis of the absorbance as functions of wavelength and modulation frequency yields the optical spectra and the decay kinetics of the transient species. The experimental technique and the analysis are described in detail. Results on t-butyl, 2-propyl and benzyl radicals generated by photolysis of the corresponding dialkyl resp. dibenzyl ketones are reported. They confirm previous spectral assignments and show that the termination reactions are diffusion controlled.

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Extinction coefficient and recombination rate of benzyl radicals. I. Photolysis of sodium phenylacetate

Cited by 50 publications

References 2 publications

Generation of Chemisorbed Benzyl Radicals on Silica Nanoparticles

Generation of Chemisorbed Benzyl Radicals on Silica Nanoparticles

PHOTOLYTIC DEGRADATION OF IBUPROFEN. TOXICITY OF THE ISOLATED PHOTOPRODUCTS ON FIBROBLASTS and ERYTHROCYTES

Absorption Spectra and Termination Kinetics of Transient Free Radicals in Solution Observed by UV./VIS. Spectroscopy with modulated excitation

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