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.

Photochemistry of Common Xanthene Fluorescent Dyes as Efficient Visible-light Activatable CO-Releasing Molecules

Abstract: Xanthene derivatives are organic dyes, some of which are routinely used in different chemical and biological applications, including human medicine. In this work, we investigated the photochemistry of some of the most common ones, fluorescein, eosin Y, and rose bengal, and major products of their photodegradation using optical spectroscopy, NMR, chromatography and mass spectroscopy techniques. These substances, usually considered (photo)chemically stable, were found to liberate carbon monoxide (CO) in 40–80% chemical yields upon extensive irradiation with visible light in aqueous solutions during their multistep concomitant degradation processes. In addition, a number of low-mass secondary photoproducts, such as phthalic and formic acids, were identified in the irradiated mixtures. We demonstrate that these common fluorescent dyes can also be considered as visible-light activatable carbon monoxide (CO)-releasing molecules (photoCORMs) under specific conditions with potential biological implications.

Influence of solvent deuteration on the spectral-luminescent and generational properties of xanthene and oxazine dyes

Abstract: Solving the problem of realizing the energetic potential of laser devices based on dye solutions involves making deliberate changes in such characteristics of the active medium as the magnitude of the induced pumping loss, the quantum yield of fluorescence, and the degree of photostability of the laser solutions. This approach presumes either the synthesis of new highly effective compounds or the improvement in the laser characteristics of already existing materials by the selection of the appropriate solvents or chemical additives [1-3]. In a series of works, an increase in the fluorescence quantum yield of certain dyes has been observed on passing from ordinary to deuterated solvents [4, 5]. Unfortunately, the literature includes no information on the attendant changes in laser characteristics of the active media, and also the question of the mechanisms suppressing the nonradiative transfer of the excitation energy in the isotropic substitution of deuterium for hydrogen ions in the solvent molecules remains quite unclear. In the present work, it is established that the use of deuterated ethyl and methyl alcohols leads to improvement in the laser efficiency of xanthene and oxazine dyes; especially favorable effects of solvent deuteration are seen in oxazine-9 (cresyl violet). It is shown that the change in spectroscopic constants controlling the processes of triplet-molecule formation and deactivation in the given materials is not much expressed, and the increase in generational characteristics of the dye solutions is due to slowing of the nonradiational internal-conversion processes S~ § So. Deuterated ethyl and methyl alcohols of analytical grade were used as the solvents; the hydrogen-containing alcohols were doubly distilled. The absorption and luminescence spectra of the dyes, preliminarily purified by the methods of recrystallizatio n and chromatography,

Multicomponent Coupling Reaction Using Arynes: Synthesis of Xanthene Derivatives.

Abstract: One-pot synthesis of xanthene derivatives was achieved by a route involving the cascade three-component coupling reaction of arynes with DMF and active methylenes followed by the SN2′ reaction of three-component coupling products with thiols. The reactivity of three-component coupling products toward nucleophiles and the further conversion of oxygen heterocycles allowing facile incorporation of structural variety were studied.