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.

Xanthen-9-ylidene protecting groups in glycerol chemistry

Abstract: The preparation of racemic, (S)- and (R)-1,2-O-(xanthen-9-ylidene)glycerol 17a, 20a and 23a and racemic, (S)- and (R)-1,2-O-(2,7-dimethylxanthen-9-ylidene)glycerol 17b, 20b and 23b is reported. The racemic derivatives 17a and 17b are converted into their stearate esters, which are then treated with dichloroacetic acid and pyrrole under mild conditions to give racemic 1-O-stearoylglycerol 25 in good yield. The xanthen-9-ylidene and 2,7-dimethylxanthen-9-ylidene residues are incorporated into 9,9-di(pyrrol-2-yl)xanthene 36 and 2,7-dimethyl-9,9-di(pyrrol-2-yl)xanthene 37. These by-products are easily removed by treatment with iron(III) chloride in diethyl ether solution. What are believed to be enantiomerically pure (R)- and (S)-1-O-stearoylglycerol 28 and 5 are similarly prepared in good yields from (S)- and (R)-1,2-O-(xanthen-9-ylidene)glycerol 20a and 23a.

Electrochemical behavior of xanthene food dye erythrosine at glassy carbon electrode and its analytical applications

Abstract: Erythrosine is a xanthene food dye used in the food industries to enhance the appearance of the food. The electrochemical behavior of erythrosine at glassy carbon electrode was investigated by cyclic and differential pulse voltammetry. The oxidation peak of erythrosine was observed in phosphate buffer of pH 5.0. The influence of different pH, scan rate and concentration were evaluated. The probable reaction mechanism involved in the oxidation of erythrosine was also proposed. Differential pulse voltammetric method with good precision and accuracy was developed for the determination of erythrosine dye in real samples. The peak currents were found to be linearly dependent on the concentration range of 1 x 10 -5 to 6 x 10 -4 M. The limit of detection (LOD) and limit of quantification (LOQ) were noticed to be 1.9 x 10 -7 and 6.6 x 10 -7 M respectively.

Surface-Enhanced Raman Spectroscopy and Density Functional Theory Calculations of a Rationally Designed Rhodamine with Thiol Groups at the Xanthene Ring

Abstract: Rhodamines are widely used dyes in fluorescence and surface-enhanced Raman spectroscopy (SERS). The latter requires adsorption of the dye onto the surface of plasmonic nanostructures, a process which requires attractive molecule–surface interactions. Here, we report an experimental SERS and computational density functional theory (DFT) study investigating the role of thiol functionalization at the xanthene ring of the rhodamine in the adsorption onto gold nanoparticles. For this purpose, a new bisthiolated rhodamine derivative was rationally designed and synthesized via a PPh3/I2 reduction route. The introduction of two thiol moieties directly at the xanthene ring provides the shortest possible distance between the molecular π-system and the metal surface for maximum SERS enhancement combined with the strong Au–S interaction for chemisorption. The comparison of experimental SERS spectra obtained from gold nanostars and a film of gold nanoparticles with results from DFT calculations (molecular electrostati...