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: A biomimetic total syntheses of antibacterial natural products (±)-callistrilones A, B, and D, the first triketone-phloroglucinol-monoterpene hybrids with an unprecedentedbenzofuro-xanthene ring system along with the postulated biosynthetic intermediate, isolated from the leaves of Callistemon rigidus, were achieved.
22 citations
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TL;DR: In this article, a co-precipitation of Cu(II)/NP was applied as a heterogeneous catalyst for synthesizing xanthenes (2-3 h, 85-97%) through Knoevenagel-Michael cascade reaction of aromatic aldehydes with 1,3-cyclic diketones in ethanol under refluxing conditions.
Abstract: Cu(NO3)2 supported on natural phosphate, Cu(II)/NP, was prepared by co-precipitation and applied as a heterogeneous catalyst for synthesizing xanthenes (2–3 h, 85–97%) through Knoevenagel–Michael cascade reaction of aromatic aldehydes with 1,3-cyclic diketones in ethanol under refluxing conditions. It was further used for regioselective synthesis of 1,4-disubstituted-1,2,3-triazoles (1–25 min, 95–99%) via a three-component reaction between organic halides, aromatic alkynes and sodium azide in methanol at room temperature. The proposed catalyst, Cu(II)/NP, was characterized using X-ray fluorescence, X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, Brunauer–Emmett–Teller, Barrett–Joyner–Halenda and inductively coupled plasma analyses. Compared to other reports in literature, the reactions took place through a simple co-precipitation, having short reaction time ( 85%), and high recyclability of catalyst (>5 times) without significant decrease in the inherent property and selectivity of catalyst. The proposed protocols provided significant economic and environmental advantages.
22 citations
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TL;DR: Deviation of the π-system from planarity due to changes in the fluorophore ionization state resulted in fluorescence properties that are atypical of common xanthene dyes.
Abstract: Fluorescent small molecules enable researchers and clinicians to visualize biological events in living cells, tissues, and organs in real time. Herein, the focus is on the structure and properties of the relatively rare benzo[ a]xanthenes that exhibit enhanced steric and electronic interactions due to their annulated structures. Three types of fluorophores were synthesized: (i) pH- and solvent-dependent seminaphthorhodafluors, (ii) pH- and solvent-independent seminaphthorhodafluors, and (iii) pH-independent but solvent-sensitive seminaphthorhodamines. The probes exhibited promising far-red to near-infrared (NIR) emission, large Stoke shifts, broad full width at half-maximum (fwhm), relatively high quantum yields, and utility in immunofluorescence staining. Deviation of the π-system from planarity due to changes in the fluorophore ionization state resulted in fluorescence properties that are atypical of common xanthene dyes.
22 citations
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TL;DR: In this article, a new series of multifunctional nanocomposites were synthesized based on a soluble poly(ether-imide), which was successfully synthesized via direct polycondensation reaction.
Abstract: In this work a new series of multifunctional nanocomposites were synthesized based on a soluble poly(ether-imide). The poly(ether-imide) was successfully synthesized via direct polycondensation reaction. A methyl rich diamine containing xanthene group as a new monomer was synthesized and used for polymerization. The xanthene based poly(ether-imide) was characterized using size exclusion chromatography (SEC) and nuclear magnetic resonance (NMR). Fe3O4 nanoparticles were imide-functionalized by a dianhydride, chitosan and phenylalanine. The functional Fe3O4 nanoparticles were incorporated into the new synthesized poly(ether-imide). Effects of the functionalized Fe3O4 nanoparticles on the thermal and combustion properties of the corresponding nanocomposites were investigated. Thermogravimetric analysis (TGA) results indicated that the thermal stability and char yields of the nanocomposites were enhanced compared to the neat poly(ether-imide). Microscale combustion calorimetry (MCC) revealed that the synthesized poly(ether-imide) had low flammability. The incorporation of functional Fe3O4 nanoparticles could further improve the combustion properties of poly(ether-imide). The high interaction between poly(ether-imide) and functional Fe3O4, the presence of an imide group and high hydroxyl content of the functional Fe3O4 nanoparticles seem to be responsible for the improvement of the thermal and combustion properties. Furthermore, the presence of methyl, ether and bulky xanthene groups in the polyimide backbone decreased the glass transition temperature (Tg) and increased the solubility in organic solvents. These properties will be useful for processing and new applications of poly(ether-imide).
22 citations
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03 Dec 1980TL;DR: In this paper, the present invention is concerned with novel xanthene compounds of the formula "STR1" wherein R' is alkyl; Y is an electron-withdrawing group and A is an anion.
Abstract: In one embodiment, the present invention is concerned with novel xanthene compounds of the formula ##STR1## wherein R' is alkyl; Y is an electron-withdrawing group and A is an anion. In another embodiment, the present invention is concerned with photographic products and processes employing these xanthene compounds.
22 citations