Showing papers on "Xanthene published in 2007"
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TL;DR: In this article, an efficient method for the synthesis of aryl-14-H -dibenzo[a, j ]xanthenes and 1,8-dioxo-octahydroxanthenses using Dowex-50W ion exchange resin as reusable eco-friendly catalyst under solvent-free conditions is described.
Abstract: An efficient method for the synthesis of aryl-14- H -dibenzo[ a , j ]xanthenes and 1,8-dioxo-octahydroxanthenes using Dowex-50W ion exchange resin as reusable eco-friendly catalyst under solvent-free conditions is described.
123 citations
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TL;DR: This protocol provides access to water-soluble dyes with large Stoke's shifts and far-red fluorescence emission that are envisioned as components of fluorescence-based sensors for a variety of imaging applications.
86 citations
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TL;DR: In this paper, a simple and efficient catalytic procedure for the synthesis of 14-aryl-14H-dibenzo[a,j]xanthene was reported.
Abstract: A simple and efficient catalytic procedure for the synthesis of 14-aryl-14H-dibenzo[a,j]xanthene is reported. Tungsten heteropoly acid catalysts are used both in bulk or supported on silica gel under solvent-free conditions at 100 °C. Good yields and short reaction time are advantages of this new method.
84 citations
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TL;DR: In this paper, the synthesis and characterization of manganese and copper corrole xanthene complexes as catalysts for water oxidation is presented. But the authors focus on the characterization of the complexes as a catalysts only.
83 citations
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TL;DR: In this paper, an efficient and facile synthesis of biologically active 14-substituted-14-H-dibenzo[a,j] xanthene derivatives was reported via three-component condensation reaction of β-naphthol and aldehydes in the presence of a catalytic amount of Preyssler type heteropoly acid, under solvent-free conditions.
Abstract: An efficient and facile synthesis of biologically active 14-substituted-14-H-dibenzo[a,j] xanthene derivatives were reported via three-component condensation reaction of β-naphthol and aldehydes in the presence of a catalytic amount of Preyssler type heteropoly acid, under solvent-free conditions. This method is very easy, rapid and high yielding reaction for the synthesis of dibenzo xanthene derivatives.
62 citations
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TL;DR: These studies reveal that, in future, a task-specific ionic liquid can be prepared and used for specific solute capture from the vapor phase and a remarkable selectivity was observed for some ionic liquids towards a specific organic solute.
Abstract: A novel study on organic solute absorption from the vapor phase is reported. The organic solutes chosen for the absorption studies include 1,4-benzodioxane, biphenyl, xanthene, and menthol. A series of imidazolium, ammonium, and guanidinium-based ionic liquids (ILs) containing several types of anions were used as absorbents. Absorption of water vapor was also studied along with the organic solutes. Absorption studies of each organic solute were performed by using a specially devised glass apparatus at 50 degrees C. It was observed that the rate of absorption increases with time and is faster in the case of 1,4-benzodioxane (24 h). The absorption process for each organic solute with different classes of ionic liquids was studied and the results were compared with each other. Absorption values of more than 25,000 ppm were observed in some ionic liquids. Distribution ratios of organic solutes in an ionic liquid and in the vapor phase were measured and the selectivity was evaluated by using the distribution ratio values. A remarkable selectivity was observed for some ionic liquids towards a specific organic solute. Importantly, it was observed that the selectivity remained constant, even though a mixture of solute was used for the absorption study. Desorption of organic vapors from ionic liquids was successfully carried out by applying a vacuum. Further, it was observed that the same ionic liquid can be repeatedly reused several times for absorption. These studies reveal that, in future, a task-specific ionic liquid can be prepared and used for specific solute capture from the vapor phase.
30 citations
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TL;DR: In this article, a one-pot, simple thermally efficient and solvent-free method for the preparation of aryl 14H-dibenzo[a,j]xanthene derivatives by condensation of β-naphthol and substituted benzaldehydes using aluminium hydrogensulfate Al(HSO4)3 as an inexpensive heterogeneous and reusable catalyst is described.
Abstract: A new, one-pot, simple thermally efficient and solvent-free method for the preparation of aryl 14H-dibenzo[a,j]xanthene derivatives by condensation of β-naphthol and substituted benzaldehydes using aluminium hydrogensulfate Al(HSO4)3 as an inexpensive heterogeneous and reusable catalyst is described. This method has the advantages of high yields, a cleaner reaction, simple methodology, short reaction times, ambient pressure, easy workup and greener conditions.
30 citations
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TL;DR: In this article, electrophilic aromatic substitution reactions are used to synthesize several triarylmethane and xanthene dyes (fluorescein, erythrosin B, thymolphthalein, and rhodamine B).
Abstract: The synthesis of dyes has long been a popular topic in organic chemistry laboratory experiments because it allows students to see first hand that reactions learned in class can be used to make compounds with useful applications In this experiment electrophilic aromatic substitution reactions are used to synthesize several triarylmethane and xanthene dyes (fluorescein, erythrosin B, thymolphthalein, and rhodamine B) These dyes can be readily synthesized using equipment found in most common second-year organic labs Hydroscopic Lewis acids, which are often troublesome to use in a typical lab setup, are avoided The dyes synthesized in this experiment can each be completed in one four-hour laboratory session Approximately 30 minutes in a subsequent period will be required for UV�vis analysis, and the student samples give UV�vis spectra that match commercially available dye samples
29 citations
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TL;DR: In this article, the synthesis of a new compound, amide-linked diporphyrin xanthene(ADPX), and its application for preparation of lead-II ion selective electrodes are described.
Abstract: The synthesis of a new compound, amide‐linked diporphyrin xanthene(ADPX), and its application for preparation of lead(II) ion selective electrodes are described. The electrode was prepared with a PVC membrane combining ADPX as a neutral carrier, 2‐nitrophenyl octyl ether (o‐NPOE) as a plasticizer and sodium tetraphenylborate (NaTPB) as an additive in the percentage ratio of 3:3:65:32 (ADPX: NaTPB: o‐NPOE: PVC, w:w). The electrode exhibited linear response with a near Nernstian slope of 28.2 mV per decade within the concentration range of 2.6×10−6 to 1.0×10−1 M lead ions, with a working pH range from 4.5 to 7.5, and a fast response time of less than 30 s. Selectivity coefficients for Pb(II) relative to a number of interfering ions were investigated. The electrode is highly selective for Pb2+ ions over a large number of cations. Several electroactive materials and solvent mediators have been compared and the experimental conditions were optimized. The sensor was applied as indicator electrode in ti...
25 citations
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TL;DR: The bis(silyl)-type bidentate ligand precursors xantsil-H2 (1a) and 2,7-di-t-butylxantsil H2 (2b) possessing the xanthene backbone were prepared by dilithiation of the 4,5-positions of 9,9-dimethyl...
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TL;DR: Pentacyclic pyrrolo- and pyrido[1,2-a]xanthene[ 1,9-de]azepines were synthesized in various oxidation states by assembling the azepine ring following two strategies: 7-endo-trig cyclization of the aryl radical derived from a gamma-methylene lactam and cyclodehydration of aldehydes.
Abstract: Pentacyclic pyrrolo- and pyrido[1,2-a]xanthene[1,9-de]azepines were synthesized in various oxidation states by assembling the azepine ring following two strategies: 7-endo-trig cyclization of the aryl radical derived from a γ-methylene lactam and cyclodehydration of aldehydes. Other strategies examined (Heck reaction and intramolecular acylation) did not afford azepines, but six-membered nitrogenated rings.
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TL;DR: A new xanthene, named blumeaxanthene was isolated from Blumea riparia DC as mentioned in this paper, and the structure was elucidated on the basis of the data of NMR, MS, IR.
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TL;DR: In this paper, a series of new bidentate NHC precursors with anthracene and xanthene skeletons were synthesized and the corresponding NHC-Pd complexes were examined.
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TL;DR: In this paper, the fluorescence quenching of xanthene dyes by TiO2 has been investigated using steady state technique and the quencher was found to obey Stern-Volmer equation and the corresponding Stern-volmer plots were linear in the range of quenchers concentration.
Abstract: The fluorescence quenching of xanthene dyes by TiO2 has been investigated using steady state technique. The dyes used are eosin, rhodamine B, rhodamine 6G. The quenching was found to obey Stern-Volmer equation and the corresponding Stern-Volmer plots were linear in the range of quencher concentration used [0–5 × 10--5] M. The quenching rate constant (kq) is in the range of 0.77–8.30 × 1012 M-1 s-1. This study reveals effective quenching of xanthene dyes with TiO2. The quenching of xanthene dyes followed electron transfer mechanism.
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TL;DR: Partition coefficients for 39 low-molecular-mass compounds between water and micelles of an ethylene oxide-propylene oxide block copolymer (Pluronic P85) and the monolauryl ether of poly(ethylene oxide) (Brij 35) have been measured by the methods of fluorescence spectroscopy, fluorescence anisotropy, and dialysis kinetics as mentioned in this paper.
Abstract: Partition coefficients for 39 low-molecular-mass compounds between water and micelles of an ethylene oxide-propylene oxide block copolymer (Pluronic P85) and the monolauryl ether of poly(ethylene oxide) (Brij 35) have been measured by the methods of fluorescence spectroscopy, fluorescence anisotropy, and dialysis kinetics. The tested compounds include aromatic hydrocarbons, phenols, naphthols, xanthene dyes, anthracycline antibiotics, and porphyrins. The multifactor analysis of the partition coefficients in terms of the linear free-energy relationships has been performed. It has been shown that the H-donating ability of compounds facilitates their solubilization in Pluronic micelles and has no effect on solubilization in micelles of monolauryl ether of poly(ethylene oxide). This difference indicates that, when solubilization occurs in Pluronic micelles, the compounds under study appear in a hydrophobic core composed of poly(propylene oxide) blocks.
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TL;DR: In this article, a simple and facile procedure for the synthesis of 14-aryl or 14-alkyl-14H-dibenzo[aj]xanthenes is described.
Abstract: A simple and facile procedure for the synthesis of 14-aryl- or 14-alkyl-14H-dibenzo[aj]xanthenes is described. The procedure takes place by the one-pot condensation of 2-naphthol with aldehydes in the presence of anhydrous ceric sulfate as the catalyst under solvent-free conventional heating and microwave irradiation.Key words: xanthene, one-pot condensation, aldehyde, 2-naphthol, ceric sulfate, solvent-free, microwave irradiation.
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TL;DR: Symmetric and asymmetric xanthene dyes have been prepared by a convenient one-step procedure from aldehyde and diol or m-aminophenol precursors using concentrated phosphoric acid as a solvent as discussed by the authors.
Abstract: Symmetric and asymmetric xanthene dyes have been prepared by a convenient one-step procedure from aldehyde and diol or m-aminophenol precursors using concentrated phosphoric acid as a solvent. This protocol provides access to water-soluble dyes with large Stoke's shifts and far-red fluorescence emission. These compounds are envisioned as components of fluorescence-based sensors for a variety of imaging applications.
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TL;DR: In this paper, the oxidative addition reactions on 4,5-bis(2-oxazolinyl)-(2,7-di-tert-butyl-9,9-dimethyl)-9H-xanthene (Xabox)/rhodium(I) complex were examined using chloroacetate and substituted diynes to give stereoselectively the corresponding methoxycarbonylmethyl-Rhodium (III) complex and rhodacyclopentadiene complexes, respectively.
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TL;DR: In this paper, the total synthesis of chromeno[4,3,2-de]quinazolin-2-ones, -quinazolines and -pyrrolo[2,1-b]quiniazolines from easily prepared 4methoxy-1-nitro-9H-xanthen-9-one was reported.
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TL;DR: In this paper, the self-assembling patterns in these supramolecular architectures were explained based on steric and electronic nature of the pendant arm of 9-phenyl-9H-xanthen-9-ol.
Abstract: Various multi carbon homologations of 9-phenyl-9H-xanthen-9-ol (1) were obtained through a C-C bond formation by reacting it with various enolisable ketones in the presence of 1,1′-(ethane-1,2-diyl)dipyridinium bistribromide (EDPBT). All the ten derivatives along with the starting xanthen-9-ol have been characterized by single crystal X-ray diffraction. They all form self-assembled superstructure in the solid state. The self-assembling patterns in these supramolecular architectures were explained based on steric and electronic nature of the pendant arm.
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TL;DR: The initial rate of the eosin Y CL reaction was dependent on the membrane permeability of the liposomes, and the reproducibility of the initial rate was better than that with fluorescein and phloxin B.
Abstract: The initial rate of horseradish peroxidase (HRP)-catalysed chemiluminescence (CL) reaction in an aqueous compartment of liposomes was applied to the estimation of membrane permeability of liposomes. HRP-encapsulated liposomes were prepared by an extrusion method, and a CL reagent and H2O2 were added into the liposomes suspensions. Fluorescein, eosin Y and phloxin B, which are xanthene dyes with different chemical structures, were used as CL reagents. Xanthene dye and H2O2 permeate into the inner phase of liposomes, resulting in initiation of the HRP-catalysed xanthene dye CL reaction with H2O2. The initial rate of the CL reaction was independent of the xanthene dye used. The reproducibility of the initial rate with eosin Y was better than that with fluorescein and phloxin B. When the membrane permeability of the liposomes was changed by altering the concentration of cholesterol in them, the initial rate of the eosin Y CL reaction was dependent on the membrane permeability of the liposomes. Copyright © 2007 John Wiley & Sons, Ltd.
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TL;DR: The title compound, C23H25BrO3, was synthesized by the reaction of p-bromo-benzaldehyde with dimedone and HClO4/SiO2 in EtOH as mentioned in this paper.
Abstract: The title compound, C23H25BrO3, was synthesized by the reaction of p-bromobenzaldehyde with dimedone and HClO4/SiO2 in EtOH. In the molecule, the dihydropyran ring adopts a boat conformation and the two cyclohexene rings are in a trans conformation.
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TL;DR: The title compound, C34H35O2N3, was synthesized by the reaction of 2-[3,6-bis(diethylamino)-9H-xanthen-9-yl]benzoyl chloride with aniline.
Abstract: In the crystal structure of the title compound, C31H37N3O2, the dihedral angle between the planes of the xanthene ring system and the spirolactam ring is 90.3°.
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TL;DR: In this article, the synthesis of two functionalized xanthenes is described, which after deprotonation represent ligands for dinuclear metal complexes, and the crystal structures of 4 and 5 are discussed.
Abstract: The syntheses of two functionalized xanthenes are described which after deprotonation represent ligands for dinuclear metal complexes. For the previously prepared [ᴿXanthdim]H₂ - which after deprotonation leads to a ligand with two adjacent β -diiminato binding sites - a significantly improved synthetic procedure is described involving the Pd catalyzed coupling of two diethyl malonate moieties to the xanthene backbone. Deprotonation of the resulting compound [Xanthmal]H2 provides a ligand with two adjacent diethyl malonate functions. To demonstrate this, [Xanthmal]H₂ was reacted exemplarily with two equivalents of LDA to obtain the lithium salt {Li₂[Xanthmal]}2 (4) which can be treated with ZnBr₂ to yield the zinc complex [Xanthmal]₂Zn₂ (5). Alternatively, 5 can be obtained directly from [Xanthmal]H₂, when ZnEt₂ is chosen as the metal precursor. The crystal structures of 4 and 5 are discussed. In summary, the results show that [Xanthmal]²⁻ is a suitable ligand for the preparation of novel dinuclear metal complexes.
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TL;DR: In this paper, the quenching of firefly bioluminescence (BL) in presence of xanthene dyes and tetratolylporphyrin was investigated.
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15 Jun 2007TL;DR: In this paper, a model of the kinetics of photoprocesses in polyatomic molecules based on four-level energy scheme is carried out, which includes the processes in dye under cw photoexcitation and takes into account a reverse intersystem crossing and photoochemical reaction from the upper triplet states.
Abstract: Modeling of kinetics of photoprocesses in polyatomic molecules based on four-level energy scheme is carried out. The
model includes the processes in dye under cw photoexcitation and takes into account a reverse intersystem crossing and
photochemical reaction from the upper triplet states. The analytical time-dependent relation for dye concentration of the
initial form was obtained taking into account the contrast of rates of various photoprocesses and using of quasistationary
approximation. It was shown that rate constant of photolysis correlates with probability of intersystem crossing of the
dyes. For the xanthene dyes in gelatin it was shown that simple experimental method of cw laser photolysis combined
with the kinetic model could be effective technique of study of upper excited states participation.
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TL;DR: In this article, various arylalkanes such as fluorenes, xanthene, anthrone, 9,10-dihydroanthracene, and diphenylmethane are effectively transformed into the corresponding aryls ketones, while amino and aldehyde functionalities remain intact.
Abstract: Various arylalkanes such as fluorenes, xanthene, anthrone, 9,10-dihydroanthracene, and diphenylmethane are effectively transformed into the corresponding aryl ketones, while amino and aldehyde functionalities remain intact, under air in the presence of cesium carbonate.
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TL;DR: In this article, a novel macrocycle containing fluorescein, C31H32O5, has a xanthene core and a benzyl unit that are planar.
Abstract: A novel macrocycle containing fluorescein, the highly fluorescent title compound, C31H32O5, has a xanthene core and a benzyl unit that are planar. The latter is rotated by 72.99 (3)° from the xanthene mean plane. The C11 alkyl tether and the xanthene group adopt a cage-like structure and the xanthene adopts a quinoid-type configuration. The compound crystallizes as a racemic mixture with one molecule of each isomer per unit cell. Even though the planes described by the xanthene and the benzene rings of different molecules are separated by 3.341 (4) and 3.73 (1) A, respectively, there is insufficient overlap between the aryl units to promote π-stacking.