Topic
Xanthene
About: Xanthene is a research topic. Over the lifetime, 2132 publications have been published within this topic receiving 34803 citations. The topic is also known as: Xanthene & dibenzo[a,e]pyran.
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TL;DR: In this paper, the authors studied the mechanism for the concentration self-quenching of the triplet states in the luminophores containing the internal heavy atoms in xanthene dyes.
Abstract: This paper studies the mechanism for the concentration self-quenching of the triplet states in the luminophores containing the internal heavy atoms. Two xanthene dyes have been chosen as objects of the study: eosin (FlBr/sup 2 -//sub 4/) and erythrosin (FlI/sup 2 -//sub 4/). The delayed fluorescence dependences, optical density changes, and phosphorescence intensity on dye concentration in the ground state are presented at room temperature. The identical values of the rate constants for erythrosin at low concentrations indicate that the annihilation is less effective than the triplet deactivation route as compared to eosin.
1 citations
Patent•
22 May 1997
TL;DR: In this paper, a photocurable material comprising a cationic dye, a quaternary borate and an ethylenically unsaturated compound was obtained by mixing adding any one of a phenolic compound, an aromatic thiol compound, amine compound and a phosphorus compound.
Abstract: PROBLEM TO BE SOLVED: To obtain a photocurable composition which can give a cured product inhibited from color reversion which is the phenomenon that the cationic dye contained redevelops a color with the lapse of time by mixing adding any one of a phenolic compound, an aromatic thiol compound, an amine compound and a phosphorus compound to a photocurable material comprising a cationic dye, a quaternary borate and an ethylenically unsaturated compound. SOLUTION: The cationic dye shows an absorption maximum in the visible region of 400-740 nm and is represented by the formula: D + .A - (wherein A is an arbitrary anion). D + is exemplified by cyanine, xanthene or oxazine. The quaternary organic borate is represented by the formula (wherein R 1 to R 4 are each an alkyl, an aryl, a silyl or a halogen; and Z + is a quaternay ammonium cation or the like) and is exemplified by n-butyltriphenyl borate. The ethylenically unsaturated compound is exemplified by methyl (meth)acrylate. The aminic compound is desirably a hindered amine. The phosphorus compound is exemplified by triphenyl phosphine. COPYRIGHT: (C)1998,JPO
1 citations
TL;DR: In this article, the synthesis of pyrazolyl analogues of DPEphos and Xantphos ligands was described, and a simple catalytic system based on Pd(OAc)2/2a was developed, which efficiently catalyses the Suzuki-Miyaura reaction of aryl halides and boronic acids.
Abstract: The present work describes the synthesis of mono- and bis-pyrazole compounds bearing flexible p-tolyl ether and rigid 4,5-dibromo-2,7-di-tert-butyl-9,9-dimethyl-9H-xanthene backbones as pyrazolyl analogues of DPEphos and Xantphos ligands, respectively. The synthesis of new pyrazolyl analogues was accomplished following an Ullmann coupling protocol, and the resulting products were isolated in overall good yields. In addition, a hybrid imidazolyl–pyrazolyl analogue bearing a xanthene backbone was synthesized using the same protocol, whereas a hybrid selanyl–pyrazolyl analogue with a xanthene backbone was synthesized in a good yield employing a second C–H activation step. The symmetrical bis-pyrazolyl and the hybrid imidazolyl–pyrazolyl analogues were found to be the most active among the new ligands evaluated in the Pd-catalysed Suzuki-Miyaura cross-coupling of aryl halides with aryl boronic acids. A simple catalytic system based on Pd(OAc)2/2a was developed, which efficiently catalyses the Suzuki–Miyaura reaction of aryl halides and aryl boronic acids and provides moderate to excellent yields of the corresponding cross-coupling products.
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