Showing papers on "Xanthene published in 1998"

Sulfonated xanthene derivatives

Abstract: The present invention describes xanthene dyes, including rhodamines, rhodols and fluoresceins that are substituted one or more times by a sulfonic acid or a salt of a sulfonic acid. The dyes of the invention, including chemically reactive dyes and dye-conjugates are useful as fluorescent probes, particularly in biological samples.

Photosensitization of Porous TiO2 Semiconductor Electrode with Xanthene Dyes

Abstract: Solar cell composed of Eosin Y-sensitized porous TiO2 electrode treated with TiCl4 showed remarkably high photon-to-current efficiency (51% at 533 nm) and solar-to-energy efficiency (1.3%, AM-1.5, 100 mW/cm2 with UV cutoff filter). Eosin Y dimer supposed to be more efficient than monomer. Turnover number of Eosin Y for excitation was more than 2.7 × 106 cycles, suggesting that Eosin Y was fairly stable unless UV light was irradiated.

Isolation and characterization of a new pyrano[4',3':6,7]naphtho[1,2-b]xanthene antibiotic FD-594.

Abstract: During our screening of microbial metabolites for effective drugs against tumor cell lines, we discovered a new pyrano[4′, 3′:6, 7]naphtho[1, 2-b]xanthene derivative, FD-594 from the fermentation broth of Streptomyces sp. TA-0256. FD-594 shows moderate activity against tumor cell lines, comparative to that of adriamycin, as well as antibacterial activity against some Gram-positive bacteria.

Fluorescent composition for the manufacture of cd-rom type optical memory disks

Abstract: A CD-ROM type optical disk, whether single-layer or multi-layer, is formed on a substrate having pits in its surface. The pits are filled with a fluorescent composition. Multiple disks such as that one can be glued on top of one another. Suitable fluorescent compositions include xanthene dyes of the eosine group, xanthene dyes of the rhodamine group, acridine dyes, oxazine dyes, azine dyes, indigoide dyes, perylene dyes, violanthrone dyes, cyanine dyes, phthalocynanine dyes, and porphyrins.

Ink, color filter, liquid crystal panel, computer and production of color filter

Abstract: PROBLEM TO BE SOLVED: To obtain ink capable of providing colored parts of color filter having good transparency, little bleeding, good adhesive properties and good light- fastness when discharged in ink-jet system by including an auriferous azopyrazolone dye and a dye including a xanthene skeleton. SOLUTION: This ink is obtained by including (A) an auriferous azopyrazolone dye having a structure of formula I (R 1 -R 4 are each H, a halogen, nitro, a 1-5C alkyl or the like; R 5 and R 6 are each H, a halogen or the like; M3 is Cr, Ni or Co; X1 + is a univalent alkali metal cation or the like) and (B) a dye having a xanthene skeleton (a dye including a xanthene skeleton of formula II in a molecule, e.g. a dye of formula III or formula IV). It is preferable that the weight ratio of A:B is (50:1) to (1:2) and the total content of A and B is 0.1-15 wt.% based on total ink weight. COPYRIGHT: (C)1999,JPO

Picosecond optical kerr ellipsometry determination of s1 sn absorption spectra of xanthene dyes

Abstract: →Sn transitions are evaluated with linear absorption and stimulated emission taken into account A bi-exciton state is revealed within the stimulated emission band Its binding energy (40 to 110 meV) and oscillator strength (03 to 06) are determined Possible laser, optical modulation and optical limiting applications of xanthene dyes are discussed

Theoretical Valence XPS and UV-Visible Absorption Spectra of Four Leuco Dyes Using MO Calculations

Abstract: Semiempirical HAM/3 MO program was used to obtain the theoretical valence X-ray photoelectron spectra (XPS) of the two leuco dyes (2′-anilino-6′-diethylamino-3′-methylspiro[isobenzofuran-1(3H),9′-[9H]xanthene]-3-one (DEAMAF) and 3,3-bis(4-dimethylaminophenyl)-6-dimethylamino-1(3H)-isobenzofuranone (CVL)) and UV-visible adsorption spectra of the four leuco dyes (DEAMAF, CVL, 2′-chloro-6′-diethylamino-3′-methylspiro[isobenzofuran-1(3H),9′-[9H]xanthene]-3-one (DEAMCF), and 3′,6′-bis(diethylamino)-spiro[isobenzofuran-1(3H),9′-[9H]xanthene]-3-one (Rhodamine B base). The calculated Al Kα photoelectron spectra were obtained using Gaussian lineshape functions of an approximate linewidth 0.10Ek (Ek = Ek′ − WD), where E′k is the vertical ionization potential (VIP) of each MO and WD is a shift to account for sample work function, polarization energy and other energy effects. On the other hand, the absorption curves were simulated with Gaussian lineshape functions of a constant linewidth of 0.02 eV. The theoretical v...

The synthesis of various cycloalkana[d]xanthones and conversion of the cyclohexa-analogue to a 7,7a-dimethylcyclohexa[d]xanthene†

Abstract: The synthesis of cyclo-penta-, -hexa- and -hepta-[d]xanthones 5 from (E)-(2-hydroxyphenyl)-5-arylpent-4-ene-1,3-diones 4, cycloalkanones and pyrrolidine is described. Reactions to modify 5 in an attempt to synthesize analogues of the five naturally occurring cyclohexa[d]xanthenes (with general formula 1) are also described: these reactions include C-methylations at C-7 and C-7a, hydride reduction of the 8-keto group, dehydroxylations and finally catalytic reduction to give 16. The stereochemistry of 16 established by NOE and an X-ray crystal structure of 9aB differs from 1 at two contiguous C-atoms.

Emission quenching via intramolecular electron transfer for fluorescein conjugates. Dependences on driving force and medium

Abstract: The fluorescence properties of conjugates of the dye, fluorescein, in which triazine or dinitrobenzoyl groups are attached to an amine function in the 5′ position have been studied. The substantial quenching of fluorescence which is observed with this modification is attributed to intramolecular electron transfer involving the xanthene moiety as electron donor (i.e., the shift of anionic charge). The fluorescein dianion which is important for neutral water solutions is more effective as an electron donor on comparison with the monoanion, as determined by the dependence of fluorescence quenching on pH. Binding of the conjugates to poly (vinyl-2-pyrrolidone) (PVP), a domain-forming polymer in water, leads to alterations of fluorescence spectra as well as changes in emission quantum yields and lifetimes. Fluorescence probes that are based on the mediation of emission properties by intramolecular electron transfer are discussed.

Why Selenoxanthone Gives an MC with Bromine: An Examination of Electronic States of Xanthones and Xanthenes by Electron Spectroscopy and ab Initio MO Calculations

Abstract: The PIES and UPS spectra of xanthone (1a), thioxanthone (1b), and selenoxanthone (1c) were measured, together with those of the corresponding xanthene (2a), thioxanthene (2b), and selenoxanthene (2...

New Potassium- and Cesium-selective Ionophoric Bis(crown ether)s Derived from Xanthene-4,5-dicarboxylic Acid

Abstract: A series of bis(crown ether)sbased-upon a xanthene-4,5-dicarboxylic acid skeletonwas prepared and their ionophoric properties towardalkali metal cations were investigated. Bis(crownether)s bearing 15-crown-5 and 18-crown-6 moietiesexhibited pronounced extraction efficiencies towardK+ and Cs+ ions, respectively, and theextraction constant estimated by solvent extractionstudies was as high as 109 for the 2-K+ and 3-Cs+ systems. Using UVtitration of potassium picrate with 2 in THF, thecomplex was found to have a structure of a completelyencapsulated guest in the host. In transportexperiments, the bis(crown ether)s showed nosignificant selectivity pattern compared withextraction results, again implying the strongcomplexation of bis(crown ether)s. Ion-selectiveelectrode studies also demonstrated that the selectiveionophoric properties of 2 toward K+ werereminiscent of the natural antibiotic valinomycinexcept for a somewhat slow response.

Isolation and Characterization of a New Pyrano[4′,3′:6,7]naphtho[1,2-b]xanthene Antibiotic FD-594.

Abstract: During our screening of microbial metabolites for effective drugs against tumor cell lines, we discovered a new pyrano[4′, 3′:6, 7]naphtho[1, 2-b]xanthene derivative, FD-594 from the fermentation broth of Streptomyces sp. TA-0256. FD-594 shows moderate activity against tumor cell lines, comparative to that of adriamycin, as well as antibacterial activity against some Gram-positive bacteria.

Color pigment, its production and cosmetic produced by using the pigment

Abstract: PROBLEM TO BE SOLVED: To facilitate the fixation of a color pigment on a specific carrier substance and stabilize the pigment in a state exhibiting bright color tone by bringing a color pigment into contact with a carrier substance in the presence of a water-soluble aluminum salt. SOLUTION: (A) A powdery hydrous silicate mineral or barium sulfate is brought into contact with (B) an aqueous solution containing a xanthene pigment expressed by the formula (X is H, Br, I or Cl; Y is H or Cl; Z is Na or K) in the presence of (C) a water-soluble aluminum salt. The component B is preferably a xanthene pigment having xanoid-type structure, concretely 9-ortho- carboxyphenyl-6-hydroxy-3-isoxanthone disodium salt, etc.

Xanthene and acridine derivatives and use thereof

Abstract: PROBLEM TO BE SOLVED: To obtain new compounds, capable of inhibiting a herpes simplex virus(HSV) and a thymidine kinase(TK) and useful for treating and preventing infectious diseases caused by the HSV SOLUTION: The xanthene and acridine derivatives are represented by formula I [W is H or a lower alkyl; X is a lower alkyl; Y is O or NR (R is H, a lower alkyl, etc); Z is an aryl or a heteroaryl], eg 9-(4-chloro-3- phenoxy)-3,4,6,7,9,10-hexahydro-3,3,6,6-tetramethyl-1,8-(2H,5H)-acridi nedione The compound represented by formula I is obtained by reacting an aldehyde represented by the formula Z-CHO with a cyclodexanedione derivative represented by formula II

Dye for highly sensitive detection of double-stranded dna

Abstract: PROBLEM TO BE SOLVED: To provide a fluorescent dye which is to be inserted into nucleic acid and detects double stranded DNA with a high sensitivity. SOLUTION: This dye is a fluorescent compd. which contains a fluorescent group selected from the group consisting of benzimidazole, benzothiazole, benzoxazole, phenanthridine, quinoline, acridine, and xanthene covalently bonded to a chain having at least two positive charges, provided the chain has terminal amino groups; when the amino group is substd., the substituent has up to 10 carbon atoms; and when the fluorescent group is phenanthridine, then the phenanthridine has an amino group at the 3- or 8-polision.

Water-soluble fibre-reactive dyes having a 5,6-difluoropyrimidin-4-ylamino group directly or indirectly attached to an aromatic ring of the dye structure

Abstract: New dyes, their manufacture and their use, the new dyes conforming to the general formula (1) Where Fb is the radical of a mono-, dis-, tris- or polyazo dye, of a 1:1 copper, 1:2 chromium or 1:2 cobalt complex mono-, dis- or triasazo dye, of an anthraquinone, phthalocyanine, metal phthalocyanine, formazan, azomethine, dioxazine, triphendioxazine, phenazine, stilbene, triphenylmethane, xanthene, thioxanthone, nitroaryl, naphthoquinone, pyrenequinone or perylenetetracarbimide dye; B is each, independently of the other one, a direct covalent bond or a bridge member which is bonded to a ring carbon atom of an aromatic carbocyclic radical or to a ring carbon or nitrogen atom of an aromatic heterocyclic radical of Fb; R is each, independently of the other one, hydrogen or alkyl of 1 to 6 carbon atoms, unsubstituted or substituted; X is the 5,6-difluoropyrimidin-4-yl group; Z has the meaning of X or is another substituent which contains a heterocylic fiber-reactive radical; n is 1 to 2.

New Possibilities for Studying Mechanism of Nitrogenase Reaction with Photodonors of Electron

Abstract: Despite a great deal of research on the field of nitrogenase, the individual role(s) of the two types of metal-sulphur clusters (P and M) found in Av1 (MoFe protein) is not clear and the mechanism of charge separation following electron transfer against the potential from Av2 (Fe protein) to Av1 is unknown. One of the most promising ways of gaining this information appears to be photoreduction of nitrogenase over a microsecond range. An alternative electron donor for nitrogenase was developed (Druzhinin S. et al., 1993) based on photoexcited eosin with NADH. Some xanthene dyes were also studied as possible photodonors. Eosin, 4′,5′-dibromofluorescein, cyanosine, erythrosin are effective photodonors for nitrogenase, fluorescein and rhodamine B or 6G are not. The main difference between these active and inactive compounds was the high quantum yield of phosphorescence for active photodonors versus high quantum yield of fluorescence for inactive photodonors. All studied photodonors can inhibit electron transfer within nitrogenase following substrate reduction at high dye concentration. For 4′,5′-dibromofluorescein this concentration is 0,1 mM, for other dyes it is less. Under the same conditions the ATPase activity was inhibited to a significantly less degree. Optimal concentration of each xanthene dye as photodonor depends on its inhibition characteristics and varies in the range of 0,03–0,1 mM.