Journal ArticleDOI
Evidence for singlet state β cleavage in the photoreaction of α-(2,6-dimethoxyphenoxy)-acetophenone inferred from time-resolved CIDNP spectroscopy
W.U. Palm,Herbert Dreeskamp +1 more
TLDR
In this paper, the photochemistry of α-(2,6-dimethoxyphenoxy)-acetophenone (1 ) was studied using CIDNP spectroscopy; an XeCl excimer laser (308 nm) and a 250 MHz 1 H nuclear magnetic resonance (NMR) spectrometer were employed.Abstract:
The photochemistry of α-(2,6-dimethoxyphenoxy)-acetophenone ( 1 ) was studied using CIDNP spectroscopy; an XeCl excimer laser (308 nm) and a 250 MHz 1 H nuclear magnetic resonance (NMR) spectrometer were employed. The results are compared with the photoreactions of α-hydroxyacetophenone ( 2 ) and α-methoxyacetophenone ( 3 ). The CIDNP spectra of 1 can be interpreted as a result of a β cleavage from the singlet state. With time-resolved CIDNP spectroscopy it is possible to detect the enol of acetophenone in a second reaction path and to observe the tautomerization to acetophenone. Evidence is presented that this reaction path starts with the photoreduction of 1 from the triplet state. Compound 2 shows α cleavage from the triplet state and no β cleavage. As expected no CIDNP spectra are observed from 3 which is known to react via a Norrish type II mechanism.read more
Citations
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Photochemotherapy of cancer: experimental research.
Johan Emelian Moan,Kristian Berg +1 more
TL;DR: A combination of injection of a tumor localizing and photosensitizing dye and local exposure of the tumor region to light constitutes the basis for PCT.
Journal ArticleDOI
Preclinical examination of first and second generation photosensitizers used in photodynamic therapy.
TL;DR: In vivo data suggest that vascular and direct tumor cell damage as well as systemic and local immunological reactions are involved in PDT responsiveness, which indicates that cellular target sites associated with PDT correlate with photosensitizer location.
Journal ArticleDOI
Photo- and radiation chemical induced degradation of lignin model compounds.
TL;DR: The basic mechanistic aspects of the photo- and radiation chemistry of lignin model compounds (LMCs) are discussed with respect to important processes related to lign in degradation.
Journal ArticleDOI
Singlet oxygen in the photodegradation of lignin models
TL;DR: In this article, the photochemical behavior of lignin models in the presence of singlet oxygen was studied and it was shown that, when the phenoxy part of the molecule shows a lower reactivity towards singlet oxidization, the oxidation of the phenol moiety to hydroquinone can occur.
Journal ArticleDOI
Benzophenothiazine and Benzoporphyrin Derivative Combination Phototherapy Effectively Eradicates Large Murine Sarcomas
TL;DR: The data suggest that the enhanced PDT effect observed with the combination of drugs is synergistic rather than additive, and a greater intracellular localization for EtNBS vs BPD‐MA.
References
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Elektronenspinresonanz freier Radikale bei photochemischen Reaktionen von Ketonen in Lösung
H. Paul,Hanns Fischer +1 more
TL;DR: In this article, electron spin resonance was used to detect and identify alkyl and acyl radicals during UV-irradiation of dialkyl aryl ketones in liquid solutions and the results were discussed with respect to the photochemical behaviour of the ketones.
Journal ArticleDOI
Paramagnetic Resonance Study of Liquids during Photolysis. II. Acetone and Solutions Containing Acetone
Henry Zeldes,Ralph Livingston +1 more
TL;DR: In this paper, the paramagnetic resonance spectra in liquid acetone and acetone solutions were studied during the course of intense irradiation with ultraviolet light, and it was shown that the radicals of the reaction CH3COCH3+RH→(CH3)2COH+R were seen.
Journal ArticleDOI
Photodegradation of lignin: a photophysical and photochemical study of a non-phenolic α-carbonyl β-O-4 lignin model dimer, 3,4-dimethoxy-α-(2′-methoxypenoxy)acetophenone
TL;DR: In this article, the photoproducts are in accordance with a β-CO bond cleavage as the primary photochemical step, leading to phenacyl and guaiacoxy radicals.
Journal ArticleDOI
Absolute chemically induced nuclear polarizations and yields from geminate radical pair reactions. A test of high-field radical pair theories
TL;DR: In this article, absolute net nuclear polarizations and reaction yields are determined for the products of geminate radical pairs formed after triplet α-cleavage of di-tert-butyl ketone and during the singlet photo-Fries reaction of p -methylphenyl- p -chlorobenzoate.
Journal ArticleDOI
Photochemistry of α-chloro- and α-bromoacetophenone. Determination of extinction coefficients for halogen–benzene complexes
W. G. McGimpsey,J. C. Scaiano +1 more
TL;DR: In this article, the photochemical dehalogenation of α-haloacetophenones (Cl, Br) in benzene solution has been examined under conditions of continuous and pulsed laser irradiation.