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 article, a simple and efficient synthesis of aryl-5H-dibenzo[b,i]xanthene-5,7,12,14-(13H)-tetraones and 3,3-(arylmethylene)bis(2-hydroxynaphthalene-1,4-diones) by the condensation of aromatic aldehydes and 2-hydroxy-1-4-naphthoquinone under extremely mild conditions using catalytic amount of H2SO4 or in the presence of
16 citations
TL;DR: In this paper, a one-pot multi-component procedure for the synthesis of xanthene-ones via reaction of aldehydes, dimedone and β-naphthol was proposed.
16 citations
TL;DR: In this paper, the correlation of dibutyl-ether-ester of xanthene dye structures with their photophysical properties is discussed with respect to their capability as fluorescent probes based on ultraviolet-visible absorption, fluorescence spectra and fluorescence lifetimes measured in different solvents.
Abstract: The correlation of dibutyl-ether-ester of xanthene dye structures with their photophysical properties is discussed with respect to their capability as fluorescent probes based on ultraviolet–visible absorption, fluorescence spectra and fluorescence lifetimes measured in different solvents. It was found that the dibutyl-ether-ester of fluorescein is very weakly emissive in aprotic solvents, but fairly strong fluorescent in alcohols. The dependence of fluorescence quantum yield (Φf) and lifetime (τf) on solvent polarity suggests non-involvement of the intra-molecular photoinduced electron transfer (PeT) mechanism, suggested previously to account for the emission efficiency of fluorescein derivatives. The xanthene dyes intend to self-assemble in aprotic solvents, less polar solvents facilitate the aggregation while hydrogen bonding disfavor it. The formation of non-emissive H-aggregates is proposed to be responsible for their fluorescent behavior. The esterification showed stronger influences on the photophysics than the etherification, i.e. the former caused larger reduction of Φf owing to the internal conversion. The halogenation decreases the fluorescence quantum yield and lifetime of the xanthene dyes, owing to the enhancement of inter-system crossing process.
16 citations
TL;DR: Lethal dye-sensitized photooxidation reactions in the black imported fire ant, Solenopsis richteri (Forel), have been defined as a function of whole body concentrations of a series of xanthene dyes.
Abstract: Lethal dye-sensitized photooxidation reactions in the black imported fire ant, Solenopsis richteri (Forel), have been defined as a function of whole body concentrations of a series of xanthene dyes. Log probit analysis of mortality data has allowed calculation of LD50 values of 1.1×10−3M for dietary levels and 2.3×10−7 moles/ gm wet weight for whole body concentrations of rose bengal in ants illuminated with 3800 μW/cm2 light for 4 h. Comparative LT50 values were calculated for the xanthene dye series and related to whole body dye concentrations.
16 citations
TL;DR: In this paper, an xanthene dye, pyronine Y, was found to exhibit opposite fluorescence behaviors at different pH values in the presence of N,N � -bis(2aminoethyl)-2,2 � -biquinoline-4,4 � -dicarboxamide-bridged bis(-cyclodextrin) (2).
Abstract: An xanthene dye, pyronine Y, was found to exhibit opposite fluorescence behaviors at different pH values in the presence of N,N � -bis(2aminoethyl)-2,2 � -biquinoline-4,4 � -dicarboxamide-bridged bis(-cyclodextrin) (2). That is, pyronine Y showed the quenched fluorescence in an acidic (pH 2.0) or a neutral (pH 7.2) environment, while the enhanced fluorescence in a basic environment (pH 12.0), with the addition of 2. Further studies by fluorescence titrations and 2D NMR indicated that different binding modes of positively charged and neutral PY molecules upon complexation with bis(-cyclodextrin) 2 should be responsible for opposite fluorescence behaviors. This result may enable the biquinolino-bridged bis(-cyclodextrin) as an efficient chemical sensor for the protonation and deprotonation of xanthene dyes. © 2005 Elsevier B.V. All rights reserved.
16 citations