Showing papers on "Xanthene published in 1974"

Photodynamic inactivation of sarcoplasmic reticulum vesicle membranes by xanthene dyes.

Abstract: — Photosensitized oxidation of sarcoplasmic reticulum (SR) vesicle membranes by a series of xanthene dyes was investigated. With increasing dye concentration and illumination time, the calcium ion uptake, ATPase activity and UV fluorescence intensity of SR decreased, and the absorbance at 241 nm increased. In xanthene dyes, the order of inactivation of the calcium uptake and ATPase activity of SR was in accord with decreasing order, of fluorescence intensity and increasing order of absorbance at 241 nm. Some regular relationships exist between the molecular structures of xanthene dyes and the photodynamic inactivation of SR membranes.

ESR Study on Fluorescein Semiquinone Radical

Abstract: The ESR spectrum of the fluorescein semiquinone radical (dianion form) produced by illumination of an alkaline aqueous solution of uranine and leuco-uranine at pH between 11 and 14 was observed and its hfs constants were determined by comparing the spectrum with those of the mono- and trianion forms of fluorescein semiquinone and those of eosm semiquinone reported by Leaver. Six protons in the xanthene ring were found to be comprised of three pairs of magnetically equivalent protons, which suggests a certain dynamic mechanism to average the coupling constants. From a temperature dependence of the line width, protonation to the –O− group followed by deprotonation from the –OH group was proposed as a plausible mechanism.

Chemiluminescence of Succinylfluorescein and Related Compounds. I. Emitting Species Produced by the Reaction of Succinylfluorescein with Oxygen in Aprotic Solvents

Abstract: In the course of our studies of the chemiluminescence of xanthene dyes, we found the violet chemiluminescence emission (CL-emission) resulting from the reaction of succinylfluorescein with oxygen in an aerated alkaline aqueous system of a high concentration of an aprotic solvent (DMSO or DMF), an especially intense emission occurring in aerated dry DMSO or DMF with tert-BuOK as base. The CL-emission comprised two emission components: an intense violet emission (a peak, at 410 nm) whose spectral distribution was similar to that of the fluorescence band which appeared during the course of the reaction, and a weak greenish-yellow emission similar to the fluorescence of the dye. By isolating and identifying the violet-fluorescent reaction product with an authentic sample, and by comparing the CL-emission with the fluorescence emission of the isolated product, it was concluded that the violet CL-emission may be attributed to the formation of an excited dianion of 3,6-dihydroxyxanthone. The reaction path leadin...

The Photochemical Reaction of 1,4-Naphthoquinone Derivatives with Hydrogen Donors

Abstract: The reaction products of the photochemical reactions of 1,4-naphthoquinone and its methyl- or halogenoderivatives with xanthene were investigated. Methyl-substituted 1,4-naphthoquinones produce the corresponding 1,4-naphthohydroquinones, but naphthoquinone and its halogeno-derivatives react to give substituted or added products by the xanthyl group in addition to the hydroquinone derivatives. Stable free radicals, which remain unchanged under atmospheric pressure, are also obtained in the latter reactions. The courses of the photochemical reactions were investigated by means of the CIDNP technique, and the reaction mechanism was discussed.

Film forming polymeric compositions of 7,7-dimethyl-7h-dibenzo (c,h)xanthene compounds

Abstract: Novel monomers of 7,7-dimethyl-7H-dibenzo(c,h)xanthene-5,9disulfonyl halide and novel high molecular weight polymers containing 7,7-dimethyl-7H-dibenzo-(c,h)xanthene residues are useful in the preparation of photographic film bases.

3-Alkyl xanthene compounds

Abstract: The compounds of this invention are 3-alkyl xanthenes having pharmacological activity such as central nervous system activity. Preferred compounds of this invention are 3-(1,2-dimethylheptyl)-5,6,7,8-tetrahydro-1-hydroxy-9-methylxanthene, 3-(1,2-dimethylheptyl)-1-hydroxy-6,9-dimethylxanthene and 3-(1,2-dimethylheptyl)-1-hydroxy-9-methylxanthene.

Studies of the ESR Spectra of Semiquinone Anions of Xanthene Dyes. Variation in the Linewidth of the Phloxine Semiquinone Anion with the Temperature and the Viscosity in Protic Solvents

Abstract: The ESR linewidths of semiquinone anions of xanthene dyes in alkaline protic solvents were studied as functions of the temperature and the viscosity. It was found that the linewidths of phloxine semiquinone, the ESR spectra of which show three hyperfine lines due to two equivalent protons, decrease with a decrease in the temperature or an increase in the viscosity of the solvents, and vary unimolecularly. Such a variation can not be explained either by a usual “chemical exchange” process between different states or by intramolecular motion. We propose that the linewidths may be due to the modulation of the hyperfine coupling constants of H atoms; the modulation results from the dissociation and/or distortion of the hydrogen bonds.

Xanthene and thioxanthene derivatives, compositions thereof and a method of preparation thereof

Abstract: The present invention relates to novel xanthene and thioxanthene derivatives of the following general formula: ##SPC1## Wherein Y represents sulfur or oxygen, R1 represents hydrogen, chlorine, trifluoromethyl or dimethylsulfamoyl, R2 represents hydrogen or fluorine; and R3 and R4 each represents hydrogen or methyl, provided that R3 and R4 may not both represent hydrogen, or R3 and R4 taken together with the nitrogen atom form a piperazine or piperidine ring optionally substituted in the 4-position by a methyl group or a 2-hydroxyethyl group, if desired, esterified with an aliphatic carboxylic acid having from 1 to 17 carbon atoms inclusive, as well as non-toxic acid addition salts thereof.

Esr study on fluorescein semiquinone radical

Abstract: The ESR spectrum of the fluorescein semiquinone radical (dianion form) produced by illumination of an alkaline aqueous solution of uranine and leuco-uranine at pH between 11 and 14 was observed and its hfs constants were determined by comparing the spectrum with those of the mono- and trianion forms of fluorescein semiquinone and those of eosm semiquinone reported by Leaver. Six protons in the xanthene ring were found to be comprised of three pairs of magnetically equivalent protons, which suggests a certain dynamic mechanism to average the coupling constants. From a temperature dependence of the line width, protonation to the –O− group followed by deprotonation from the –OH group was proposed as a plausible mechanism.

Xanthene derivatives and process for the preparation thereof

Abstract: Xanthenes of the formula Z-CHR 1 R 2 wherein Z is 2-xanthenyl or 2-xanthenyl substituted at the 1-, 3-, 4-, 5-, 6-, 7- or 8-position by F, Cl or Br, R 1 is CH 2 OH or CH 2 OAc wherein Ac is alkanoyl of 2-4 carbon atoms, and R 2 is H or alkyl of 1-4 carbon atoms, have antiphlogistic activity.

Photo‐oxidation in the synthesis of17O and 18O labelled compounds: Synthesis of xanthone‐18O1

Abstract: It it shown that the photo-oxidation of aromatic molecules containing an active methylene group can be used to introduce isotopic oxygen. Photo-oxidation of xanthene results in the formation of xanthone with the oxygen label appearing in the product at the carbonyl group. In this way, 100% enrichment can be realized. A brief discussion of other systems to which this method may be extended is also given.

Synthesis of some 9-(Indol-3'-yl)xanthene derivatives

Abstract: 9,9-Dichloroxanthene reacts with 1-substituted, 2-substituted and 1,2-disubstituted indoles to yield blue solids which are converted into 9-(indol-3'-y1)xanthenes by water or by sodium ethoxide in ethanol. With a 3-substituted indole, reaction occurs at the 2-position.

Formation and Reactions of Long Lived Xanthene Dye Radicals. III. Spectroelectrochemical Investigations on the Reduction of Xanthene Dyes

Abstract: In connection with photochemical studies on the formation of certain xanthene dye radicals spectroelectrochemical investigations have been performed in order to obtain data on the stability of semireduced xanthene dye radicals which were required for the interpretation of the photochemical measurements described in parts I and II of this series of papers. Im Zusammenhang mit photochemischen Untersuchungen uber die Bildung von Radikalen einiger Xanthenfarbstoffe wurden spektroelektrochemische Messungen durchgefuhrt, um zusatzliche Informationen uber die Stabilitat solcher Radikale zu erhalten. Diese sind fur die Deutung der in den Teilen I und II beschriebenen photochemischen Prozesse von Bedeutung.

Photo-induced isomerization of 2-acyl-3-methyl-1,4-naphthoquinone-2,3-epoxide

Abstract: 2-Acyl-3-methyl-1,4-naphthoquinone-2,3-epoxide(1) isomerizes photochemically to give lactone. The spectral data and chemical reactions of the lactone are compatible with structure(2). Photochemical reaction of (1) with xanthene was also described.

Studies of the esr spectra of semiquinone anions of xanthene dyes. variation in the linewidth of the phloxine semiquinone anion with the temperature and the viscosity in protic solvents

Abstract: The ESR linewidths of semiquinone anions of xanthene dyes in alkaline protic solvents were studied as functions of the temperature and the viscosity. It was found that the linewidths of phloxine semiquinone, the ESR spectra of which show three hyperfine lines due to two equivalent protons, decrease with a decrease in the temperature or an increase in the viscosity of the solvents, and vary unimolecularly. Such a variation can not be explained either by a usual “chemical exchange” process between different states or by intramolecular motion. We propose that the linewidths may be due to the modulation of the hyperfine coupling constants of H atoms; the modulation results from the dissociation and/or distortion of the hydrogen bonds.

Synthesis of some 9-(indol-3′-yl)-xanthene derivatives

Abstract: 9,9-Dichloroxanthene reacts with 1-substituted, 2-substituted and 1,2-disubstituted indoles to yield blue solids which are converted into 9-(indol-3'-y1)xanthenes by water or by sodium ethoxide in ethanol. With a 3-substituted indole, reaction occurs at the 2-position.

Mass spectra of imidazo[2,1-b]thiazole and thiazolo[3,2-f]xanthene derivatives

Abstract: The general principles of the mass-spectrometric disintegration of imidazo [2,1-b]thiazole and thiazolo[3,2-f]xanthene derivatives were established, and the characteristic fragments were identified. Disintegration proceeding with cleavage of the bonds in the thiazole ring of the 2(3)-ring system is characteristic of all of the investigated compounds. The cleavage of the S-C bonds, which are the weakest in the investigated systems, proceeds especially readily. Intense peaks of ions due to stepwise disintegration of the pyrimidine ring are also observed in the spectra of thiazoloxanthenes.