Showing papers on "Xanthene published in 2000"

Steady hydrogen evolution from water on Eosin Y-fixed TiO2 photocatalyst using a silane-coupling reagent under visible light irradiation

Abstract: A chemical fixation of xanthene dyes on platinized TiO 2 particles via silane-coupling reagent was attempted in order to construct a stable dye-sensitized photocatalyst system in water. The Eosin Y fixed Pt-TiO 2 (E.Y-TiO 2 ) exhibited steady H 2 production from aqueous triethanolamine solution (TEOA aq.) under visible light irradiation for long time, and the H 2 evolution reproduced even after the exchange of TEOA aq., while the H 2 evolution from the mixture of Eosin Y (E.Y) and Pt-TiO 2 ceased in 10 h. The turnover number of the dye molecule fixed on TiO 2 surface reached more than 10,000, and the quantum yield of the E.Y-TiO 2 at 520 nm was determined to be about 10%.

Rhodamine Fluorescent Dimers Adsorbed on the Porous Surface of Silica Gels

Abstract: Rhodamine 6G (R6G)-doped silica gels were prepared through the sol−gel process using dye concentrations ranging from 4.00 × 10-6 to 6.40 × 10-4 M. The adsorption of the R6G on the porous surface of the silica gels determined the formation of R6G fluorescent J-dimers as concentration increased, in concordance with the behavior reported for other xanthene molecules as rhodamine B (RB) and rhodamine 110 (R110) also doped in silica gels. The photophysical study of the R6G fluorescent dimers doped in silica gels was done through the recording of the excitation and emission fluorescence spectra as well as the measurement of the lifetime values. The exciton theory was used for the elucidation of the adsorption angle (θ), the angle between the monomer units (α), and the separation distance between the molecules (R) of the R6G fluorescent dimers. The angle between the monomer units (α) and the separation distance between the molecules (R) were also determined for RB and R110 fluorescent dimers doped in silica gels.

Xanthene dyes and their application as luminescence quenching compounds

Abstract: The quenching compounds of the invention are nitrogen-substituted xanthenes that are substituted by one or more aromatic or heteroaromatic quenching moieties. The quenching compounds of the invention exhibit little or no observable fluorescence and efficiently quench a broad spectrum of luminescent compounds. The chemically reactive quenching compounds possess utility for labeling a wide variety of substances, including biomolecules. These labeled substances are highly useful for a variety of energy-transfer assays and applications.

Synthesis of fluorinated xanthene derivatives

Abstract: Facile syntheses for fluorinated resorcinol and aminophenol derivatives are provided that yield isomer-free products in good yield. These novel methods use generally available precursors and standard laboratory reagents and equipment to reproducibly produce these synthetically useful reagents in relatively large quantities. The resulting fluorinated resorcinols and aniinophenols possess utility in the preparation of fluorinated fluorescein and rhodol dyes.

Wide bite angle amine, arsine and phosphine ligands in rhodium- and platinum/tin-catalysed hydroformylation

Abstract: New wide bite angle amine, arsine and mixed phosphineamine and phosphinearsine ligands based on xanthene backbones were synthesized. The co-ordination chemistry and the catalytic performance of these ligands were compared to those of the parent phosphine ligands. The amine based xanthene ligands do not form rhodium–hydride complexes and therefore give very poor rhodium hydroformylation catalysts. The catalytic performance of the xantarsine and the mixed xantphosarsine ligands is comparable with that of the xantphos ligands and they form similar (ligand)Rh(CO)2H and [(ligand)Rh(CO)2]2 complexes. In the platinum/tin-catalysed hydroformylation the xantarsine and the mixed xantphosarsine ligands proved to be superior to the xantphos ligands. The remarkably high selectivity and activity that is displayed by the mixed xantphosarsine ligand is explained by its wide natural bite angle and the formation of cis co-ordinated platinum complexes.

Solid−Liquid Equilibrium and Excess Enthalpy Measurements in Binary {Dibenzofuran or Xanthene + Normal Long-Chain Alkane} Systems

Abstract: This paper is a continuation of our previous studies on thermodynamic properties of binary systems formed by a long-chain n-alkane and a polyaromatic. Solid−liquid equilibrium and enthalpies of mix...

Hydroxy-substituted triarylcarbenium bromides. Synthesis, structure, derivatization and facile conversion to highly substituted xanthenes

Abstract: The tris(3,5-dialkyl-2-hydroxyphenyl)carbenium bromides (2a) (3-tert-butyl, 5-methyl) and 2b (3,5-di-tert-butyl) have been prepared by the oxidation of the corresponding tris(3,5-dialkyl-2-hydroxyphenyl)methanes with bromine. Compound 2a has been fully characterized by a single crystal X-ray study, which shows that the bromide, atypically, does not bind to the central carbon atom. The materials 2 are reactive, and the trityl alcohol (4a), methyl (7a, 7b) and phenyl (8a) derivatives can be readily prepared in good yield by reaction of 2 with the appropriate anions; X-ray structures for 4a, 7b (as its lithium salt) and 8a are reported. In solution, 2a and 4a undergo a facile, uncatalyzed, controllable intramolecular dehydration to produce the corresponding xanthene derivatives; X-ray structures for the xanthene carbocation (bromide salt) (3a) and the 9-hydroxy derivative (5a) are also reported.

Fluorescence dyes and their use as fluorescence markers

Abstract: The subject matter of the invention are new xanthene derivatives of the formula I, wherein R1,R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, and X, Y, are as defined herein. The compounds according to the invention provide molecules that are—due to their spectral properties (absorption maxima in the range of approx. 650 nm and above as well as emission maxima above 670 nm)—very suitable for the use as dyes and in particular as fluorescence dyes. The compounds of the formula I according to the invention are used for the production of fluorescence conjugates, for their application in immunoassays, for DNA analytics, for in-vivo diagnostics or as a laser dye.

Dye compositions and uses

Abstract: A composition comprising a solvent (preferably water); at least one metallised azo colorant selected from Acid Red 183, Acid Yellow 54, Acid Red 179, Acid Yellow 99, Acid Red 191, Acid Red 186 and Acid Red 201 and optional shading component; and at least one xanthene colorant selected from Acid Red 52, Acid Red 50 and Acid Red 289. Also, processes for making patterned substrates, particularly colour filters, displays comprising these colour filters and ink-jet printer cartridges containing the composition.

Fluorescent dyes and their use as fluorescent labelling agents

Abstract: 9-Phenylxanthene derivatives (I) are new. Xanthene derivatives of formula (I) are new: R1-R5 = H, alkyl, aryl, heteroaryl, alkoxy, CN, OH, halogen, NCO, NCS, COOH (or derivative), SO3H (or derivative) or optionally substituted amino; R6-R11 = H, halogen or optionally substituted alkyl; X, Y = electron-withdrawing groups, or one is an electron-withdrawing group and the other is optionally substituted amino. Independent claims are also included for the following: (1) a conjugate of a compound (I) and at least one biomolecule; (2) a method for determining a substance by detecting a specific binding reaction through a change in absorption, fluoresce or fluorescence polarization using the conjugate of (1); and (3) a process for preparing compounds (I).

Organic polymer material containing xanthene-2,7-diol compound

Abstract: PROBLEM TO BE SOLVED: To prevent an organic polymer material from the deterioration of its quality such as the change of a physical property even when it experiences thermal history over time during being processed or used by compounding one or more organic compounds having a specific structure with an organic polymer. SOLUTION: A compound combined with an organic polymer is represented by the formula, wherein each of R1, R2 and R3 is hydrogen atom, a 1-4C straight- or branched-chain alkyl group and these may be the same or different to each other. R4 is hydrogen atom, a 1-18C linear, branched or cyclic alkyl group or a (un)substituted aryl group. Preferably, an organic polymer material further comprises a phenolic antioxidant and/or phosphorous antioxidant together with a compound of the formula. The amount of the compound of the formula is preferably 1-20 wt.% relative to the total amount of the polymer material and said antioxidant.

Naphthalimide Dyes and Pigments

Abstract: The article contains sections titled: 1. Introduction 2. Alkoxynaphthalimides 3. 4-Aminonaphthalimides 4. 1′,8′-Naphthoylenebenzimidazoles 5. Imides of Naphthalene-1,4,5,8-tetracarboxylic Dianhydride 6. 1′,8′-Naphthoylenebenzimidazole Peridicarboximides 7. Bis-benzimidazole Derivatives of Naphthalene-1,4,5,8-tetracarboxylic acid 8. 1′,8′-Naphthoylenepyrazoles 9. Benzo[k,l-]xanthene- and Benzo[k,l-]thioxanthene-3,4- dicarboximides 10. Azo- and Azomethinenaphthalimides 11. Perylene-3,4,9,10-tetracarboxydiimides

New fluorescent pigment and its use as fluorescent marker

Abstract: PROBLEM TO BE SOLVED: To obtain a new fluorescent pigment suitable for coupling with a biological molecule, having a high quantum efficiency and capable of suppressing nonspecific bonding to a biological compound or a solid phase to a degree as low as possible. SOLUTION: A xanthene derivative of the formula (R1 to R5 are each H, an alkyl, an aryl or the like; R6 to R11 are each H, an alkyl or the like; X and Y are each an electrophilic group or the like), for example, 3',6'-bis(2- benzothiazolylidenecyanomethine)fluoran. A derivative of the formula is obtained, for example, by adding a 3',6'-leaving group-substituted fluoran derivative to a mixture of a lithium diisopropylamide solution and an equimolar amount of a CH-acidic component, and heating the obtained compound under reflux followed by purification. A xanthene conjugate is obtained by compounding a derivative of the formula with at least one kind of a biological molecule (preferably, a mononucleotide or the like). The conjugate is suitably used for diagnostic analysis, nucleic acid analysis or the like.

Hydroxy-Substituted Triarylcarbenium Bromides. Synthesis, Structure, Derivatization and Facile Conversion to Highly Substituted Xanthenes.

Abstract: The tris(3,5-dialkyl-2-hydroxyphenyl)carbenium bromides (2a) (3-tert-butyl, 5-methyl) and 2b (3,5-di-tert-butyl) have been prepared by the oxidation of the corresponding tris(3,5-dialkyl-2-hydroxyphenyl)methanes with bromine. Compound 2a has been fully characterized by a single crystal X-ray study, which shows that the bromide, atypically, does not bind to the central carbon atom. The materials 2 are reactive, and the trityl alcohol (4a), methyl (7a, 7b) and phenyl (8a) derivatives can be readily prepared in good yield by reaction of 2 with the appropriate anions; X-ray structures for 4a, 7b (as its lithium salt) and 8a are reported. In solution, 2a and 4a undergo a facile, uncatalyzed, controllable intramolecular dehydration to produce the corresponding xanthene derivatives; X-ray structures for the xanthene carbocation (bromide salt) (3a) and the 9-hydroxy derivative (5a) are also reported.