Showing papers on "Xanthene published in 1985"

Efficient plastic-host dye lasers

Abstract: Efficient laser generation has been obtained from xanthene dyes impregnated into modified polymethyl methacrylate. The stability is good, supporting extended operating lifetime. We discuss the mechanisms responsible for photobleaching and conversion efficiency of these dyes in polymer matrices.

Xanthene dyes as sensitizers for the photoreduction of water

Abstract: — Some photochemical and photophysical properties of a group of xanthene dyes have been studied in relation to their roles as sensitizers for the photoreduction of water. New spectroscopic and kinetic measurements have been carried out with these dyes. The triplet states of the dyes undergo energy-transfer and electron-transfer, but with rate constants differing by two orders of magnitude in favour of the former pathway. The very efficient transfer of triplet energy from a group of dyes to an acceptor molecule led to the design of a greatly improved system for the photochemical production of hydrogen.

Adsorption and chemical stability of a cationic aggregating ester - propantheline bromide - on silica surfaces in aqueous dispersions.

Abstract: The adsorption behavior of cationic aggregating substances such as antimicrobial quats or phenothiazine derivatives on silica surfaces in aqueous media has been extensively investigated. However, the chemical stability of adsorbates in such systems was unknown. Propantheline bromide (PPBr) was selected as a model to investigate the stability of hydrolyzable substances in silica-containing aqueous dispersions or in adsorbates on silica carriers used for solid drugs. The quaternary ester PPBr showed an appreciable adsorption on the silica surface, the extent of which was increased by raising the pH of the aqueous phase or by the addition of neutral salts such as NaNO3. In parallel to the adsorption process, hydrolysis of PPBr occurs in these aqueous silica dispersions to yield xanthene carbonic acid and a quaternary alcohol component. Adsorption and hydrolysis were found to be mutually influencing reactions. Because of the adsorption of PPBr, the rate of ester decomposition was enhanced in these silica dispersions when compared to aqueous solutions of PPBr at the same pH. Simultaneously, an increase in PPBr adsorption is observed, as well as adsorption of the decomposition product xanthene carbonic acid. This result can be attributed to ion-pair adsorption of the latter with PPBr. The rate constants of PPBr decomposition were found to depend directly on the silica content of the dispersion, although at higher concentrations a decreased catalytic effect was observed. These phenomena are discussed on the basis of the adsorbate structure and exchange processes.

Reactive dyestuffs, their preparation and their use

Abstract: Reactive dyes of the formula where D is the radical of a dye of the monoazo, polyazo, metal complex azo, anthraquinone, phthalocyanine, formazan, azomethine, dioxazine, phenazine, stilbene, triphenylmethane, xanthene, thioxanthone, nitroaryl, naphthoquinone, pyrenequinone or perylenetetracarbimide series, R1 is hydrogen or a substituted or unsubstituted C1-4-alkyl radical, and X is a vinyl, beta -sulphatoethyl, beta -thiosulphatoethyl, beta -chloroethyl or beta -acetoxyethyl group, other than the reactive dye of the formula: are particularly suitable for dyeing and printing cellulose-containing fibre materials by the cold pad-batch process, producing dyeings and prints having good fastness properties in a high yield

The lactone form of fluorescein: Crystal structure of the 1:1 molecular complex of fluorescein with methanol

Abstract: The structure of the fluorescein molecule in its i:i complex with methanol was determined by x-ray crystallographic analysis with anisotropic refinement to R = 0.043. The molecule has lactone structure. The plane of the lactone ring is perpendicular to the tricyclic xanthene fragment. The methanol molecules are hydrogen bonded to fluorescein and apparently stabilize the lactone form which converts to the zwitterionic form upon storage. IR spectral and x-ray phase analysis of the yellow and red polycrystalline samples of fluorescein obtained from water and methanol shows that the color of the samples does~not correspond unequivocally to the molecular form, The red samples from methanol and water have different structure, which indicates the presence of solvent molecules or the existence of polymorphic modifications of the quinoid form of fluorescein.

Reactive dyes, process for their preparation and use thereof

Abstract: The invention relates to reactive dyes of the formula ##STR1## wherein D is the radical of a dye of the monoazo or polyazo, metal complex azo, anthraquinone, phthalocyanine, formazan, azomethine, dioxazine, phenazine, stilbene, triphenylmethane, xanthene, thioxanthone, nitroaryl, naphthoquinone, pyrenequinone or perylenetetracarbimide series, each of R1 and R2 independently is hydrogen or an unsubstituted or substituted C1 -C4 alkyl radical, X1 is an unsubstituted or substituted aminofluoro-s-triazine radical, and X2 is a heterocyclic reactive radical which is attached direct to the radical D through the --N(R2) bridge member, excepting an unsubstituted or substituted aminofluoro-s-triazine. These dyes are particularly suitable for dyeing and printing cellulosic fibre material by the cold pad-batch method and give dyeings and prints of good fastness properties and high tinctorial strength.

Photoactivable bleaching/detergent composition

Abstract: Detergent compositions adopted for bleaching via photoactivation, e.g., by irradiation with visible light, are comprised of (i) at least one sensitizing agent of xanthene dyestuff type, e.g., a fluorescein, and (ii) at least one cyclic tertiary mono-, di- or tetramine, e.g., DABCO.

Stabilized organic compound

Abstract: PURPOSE:To obtain an org. compd. which does not cause deterioration by oxidation even when exposed to a high-temperature atmosphere, by adding a specified xanthene compd. and a light stabilizer to an org. compd. CONSTITUTION:0.01-10pts.wt. light stabilizer and 0.001-10pts.wt. compd. of the formula (wherein R1-R9 are each H, alkyl, cycloalkyl, aryl, aralkyl, alkoxy, acyloxy, hydroxyl, hologen, amino, nitro; R is H, alkyl, cycloalkyl, aryl, aralkyl, hydroxyl, halogen, carboxyl, carboalkoxy) are blended with 100pts.wt. org. compd. Examples of the compds. of the formula are 2,7-dimethylxanthene, 9- benzylxanthene, etc.

Benzo(thio)xanthene compound and liquid crystal composition containing it

Abstract: NEW MATERIAL:A benzo(thio)xanthene compound of formula I, where X is O or S; R is an alkyl, an alkoxy, benzyloxy, a trans-4-alkylcyclohexyl(alkyloxy), an alkylamino or a heterocyclic group; R is a trans-4-alkylcyclohexylalkyl, a group of formula II (where R is an alkylene; R is benzyloxy or a trans-4- alkylcyclohexylalkyloxy), etc. USE:A dichroic dye used for a liquid crystal composition of guest-host effect type (having a high dichroic ratio and excellent solubility in a liquid crystal). PREPARATION:A compound of formula III is diazotized with sodium sulfite, etc. and then decomposed with copper sulfate, etc.

Spirolactone of Xanthene. II. Synthesis and Molecular Structure of 2′,5,7′-Trichlorospiro[benzofuran-3(2H),9′-[9H]xanthen]-2-one

Abstract: The title compound has been synthesized by the novel condensation reaction of p-chlorophenol with oxalic and sulfuric acids; its crystal and molecular structures have been determined by the single crystal X-ray diffraction method. The space group is C2/c. There are eight molecules of the title compound in the unit cell of dimensions a=21.316(9), b=17.267(4), c=9.158(6) A, and β=94.05(5)°. The structure was solved by the direct method and refined by the block-diagonal least-squares method to a value of 0.088 for R using 1993 independent observed reflections with Fo>3σ(Fo). The molecule possesses three phenyl rings fused to spirolactone and the dihedral angles between the phenyl rings are 73.60°, 83.60°, and 22.81°.

Spirolactone of xanthene. ii. synthesis and molecular structure of 2′,5,7′-trichlorospiro(benzofuran-3(2h),9′-(9h)xanthen)-2-one

Abstract: The title compound has been synthesized by the novel condensation reaction of p-chlorophenol with oxalic and sulfuric acids; its crystal and molecular structures have been determined by the single crystal X-ray diffraction method. The space group is C2/c. There are eight molecules of the title compound in the unit cell of dimensions a=21.316(9), b=17.267(4), c=9.158(6) A, and β=94.05(5)°. The structure was solved by the direct method and refined by the block-diagonal least-squares method to a value of 0.088 for R using 1993 independent observed reflections with Fo>3σ(Fo). The molecule possesses three phenyl rings fused to spirolactone and the dihedral angles between the phenyl rings are 73.60°, 83.60°, and 22.81°.