Showing papers on "Xanthene published in 2012"
TL;DR: In this article, the efficiency, generality and applicability of novel Bronsted acidic ionic liquid triethylamine-bonded sulfonic acid {[Et 3 N−SO 3 H]Cl, N, N -diethyl- N -sulfoethanammonium chloride} as homogeneous and green catalyst for organic transformations under various conditions are studied.
140 citations
TL;DR: In this article, the physicochemical properties of the synthesized Zn/Cr-CO3 LDH, prepared by co-precipitation method at constant pH, were determined by several techniques such as powder X-ray diffraction (PXRD), Fourier Transform Infrared (FT-IR), thermo gravimetric/differential thermal analysis (TG/DTA), BET surface area, scanning electronic microscope (SEM), transmission electron microscope (TEM) and optical absorption spectra.
128 citations
TL;DR: It is shown that the radiative lifetime of rhodamines can be correlated to the charge transfer from the phenyl toward the xanthene moiety occurring upon the S(0) ← S(1) de-excitation, and to thexanthene/phenyl relative orientation assumed in the S (1) minimum structure.
Abstract: Although lifetimes and quantum yields of widely used fluorophores are often largely characterized, a systematic approach providing a rationale of their photophysical behavior on a quantitative basis is still a challenging goal. Here we combine methods rooted in the time-dependent density functional theory and fluorescence lifetime imaging microscopy to accurately determine and analyze fluorescence signatures (lifetime, quantum yield, and band peaks) of several commonly used rhodamine and pyronin dyes. We show that the radiative lifetime of rhodamines can be correlated to the charge transfer from the phenyl toward the xanthene moiety occurring upon the S0 ← S1 de-excitation, and to the xanthene/phenyl relative orientation assumed in the S1 minimum structure, which in turn is variable upon the amino and the phenyl substituents. These findings encourage the synergy of experiment and theory as unique tool to design finely tuned fluorescent probes, such those conceived for modern optical sensors.
105 citations
TL;DR: In this paper, a general synthetic route to the synthesis of 1,2-dihydro-1-arylnaphtho[1,2]-e][1,3]oxazine-3-one and 14-substituted-14H-dibenzo[a,j]xanthenes derivatives has been developed using ZnO-NPs under thermal and solvent-free conditions.
83 citations
TL;DR: Application of the small bite-angle ligands L1 and L2 in the highly selective asymmetric hydroformylation (AHF) of the challenging substrate 2,3-dihydrofuran yielded the 2-carbaldehyde as the major regioisomer in up to 68% yield (with ligand L2) along with good ee's of up to 62%.
Abstract: A small family of new chiral hybrid, diphosphorus ligands, consisting of phosphine-phosphoramidites L1 and L2 and phosphine-phosphonites L3a–c, was synthesized for the application in Rh-catalyzed asymmetric hydroformylation of heterocyclic olefins. High-pressure (HP)-NMR and HP-IR spectroscopy under 5–10 bar of syngas has been employed to characterize the corresponding catalyst resting state with each ligand. Indole-based ligands L1 and L2 led to selective ea coordination, while the xanthene derived system L3c gave predominant ee coordination. Application of the small bite-angle ligands L1 and L2 in the highly selective asymmetric hydroformylation (AHF) of the challenging substrate 2,3-dihydrofuran (1) yielded the 2-carbaldehyde (3) as the major regioisomer in up to 68% yield (with ligand L2) along with good ee’s of up to 62%. This is the first example in which the asymmetric hydroformylation of 1 is both regio- and enantioselective for isomer 3. Interestingly, use of ligand L3c in the same reaction compl...
82 citations
TL;DR: In this article, a mild, simple and convenient procedure for the synthesis of xanthene derivatives is described via three component condensation of aldehydes with 2-naphthol, 1,3-cyclohexanedione and/or a mixture of 2-Naphthols and 1, 3-cycloehexanediones using succinimide-N -sulfonic acid as an efficient, cheap and readily synthesis catalyst under solvent-free conditions.
80 citations
TL;DR: In this article, an efficient and environmentally adapted synthesis of xanthene derivatives by condensation of a wide range of aryl aldehydes and 1,3-cyclohexanediones in water using a catalytic amount of Fe3O4 nanoparticles is explained.
76 citations
TL;DR: The magnitude of the dye–micelle interaction increased from SDS, P-123 and finally CTAB micelles due to the charges between dye and micelle, and among the xanthenes, their hydrophobic characteristics.
Abstract: Photosensitizers (PS) photodynamic activities are regulated by their location in the biological target, which modulates their photophysical and photochemical features. In this work the PS partition for the Xanthene Dyes Fluorescein ( FSC ), Eosin Y ( EOS ), Erythrosin B ( ERY ) and Rose Bengal B ( RBB ) in biomimetic models (SDS, CTAB and Pluronic P-123 micelles) and the effects on their photophysical characteristics are evaluated. The hydrophobic and electrostatic forces that govern the PS–micelle interaction are analyzed. At physiological pH (7.25), the ability of the dianionic protolytic form of the dyes to be positioned into the micelle palisade and its micelle interaction depends not only on the hydrophobicity of the dye but also on the micellar surface charge. The Binding Constants obey exactly the same order of the Partition Coefficients for the dyes in P-123 and CTAB micelles. The Stern–Volmer treatment pointed out that dyes are located inside the micelle, especially ERY and RBB . The magnitude of the dye–micelle interaction increased from SDS, P-123 and finally CTAB micelles due to the charges between dye and micelle, and among the xanthenes, their hydrophobic characteristics. Within the micelle pseudo phase, ERY and RBB are still very efficient photosensitizers exhibiting high quantum yield of singlet oxygen, which turns them very attractive especially with P-123 polymeric system as drug delivery systems in photodynamic therapy.
74 citations
TL;DR: The results attest that decolorization of Ery is essentially due to enzymatic and adsorption phenomena.
Abstract: Biodegradation of a xanthene dyes was investigated for the first time using anaerobic granular sludge. On a first screening, biomass was able to decolorize, at different extents, six azo dye solutions: acid orange 7, direct black 19, direct blue 71, mordant yellow 10, reactive red 2 and reactive red 120 and two xanthene dyes—Erythrosine B and Eosin Y. Biomass concentration, type of electron donor, induction of biomass with dye and mediation with activated carbon (AC) were variables studied for Erythrosine B (Ery) as model dye. Maximum color removal efficiency was achieved with 4.71 g VSS L−1, while the process rates were independent of the biomass concentration above 1.89 g VSS L−1. No considerable effects were observed when different substrates were used as electron donors (VFA, glucose or lactose). Addition of Ery in the incubation period of biomass led to a fivefold increase of the decolorization rate. The rate of Ery decolorization almost duplicated in the presence of commercial AC (0.1 g L−1 AC0). Using different modified AC samples (from the treatment of AC0), a threefold higher rate was obtained with the most basic one, $${\text{AC}}_{{\text{H}}_2}$$
, as compared with non-mediated reaction. Higher rates were obtained at pH 6.0. Chemical reduction using Na2S confirmed the recalcitrant nature of this dye. The results attest that decolorization of Ery is essentially due to enzymatic and adsorption phenomena.
64 citations
TL;DR: A new class of rhodamines for the application as indicator dyes in fluorescent pH sensors is presented, which derives from photoinduced electron transfer between non-protonated amino groups and the excited chromophore which results in effective fluorescence quenching at increasing pH.
61 citations
TL;DR: In this article, a one-pot multi-component reaction of dimedone and 2-naphthol with various aryl aldehydes using ZnO nanoparticles under solvent-free conditions is described.
TL;DR: There is ongoing interest in near-infrared (NIR) absorbing and emitting dyes for a variety of biomedical and materials applications and simple and efficient synthetic procedures enable the judicious tuning of through-space polar (field) effects as well as low barrier hydrogen bonding to modulate the HOMO-LUMO gap in xanthene dyes.
Abstract: There is ongoing interest in near-infrared (NIR) absorbing and emitting dyes for a variety of biomedical and materials applications. Simple and efficient synthetic procedures enable the judicious tuning of through-space polar (field) effects as well as low barrier hydrogen bonding to modulate the HOMO-LUMO gap in xanthene dyes. This affords unique NIR-absorbing xanthene chromophores.
TL;DR: In this paper, the application of nickel based earth abundant inorganic solids as catalysts in xanthene dye sensitized systems was evaluated for photocatalytic H2 production from water.
TL;DR: In this paper, the inhibition of xanthene (XEN) on the corrosion of mild steel in 0.5 m H 2 SO 4 was studied by gravimetric and UV-visible spectrophotometric methods at 303 −333 K. The inhibition efficiency was found to increase with increase in XEN concentration but decreased with temperature.
TL;DR: In this paper, a series of hole-transporting molecules based on spiro(fluorene-9,9′-xanthene) were designed and synthesized by a copper-catalyzed modified Ullmann reaction.
TL;DR: Tetrahydrobenzo[c]xanthenes-11-ones was synthesized by a three component reaction of α-naphthol, aromatic aldehyde and dimedone using Ceric ammonium nitrate as a suitable eco-friendly catalyst.
TL;DR: In this paper, a simple, efficient, and environmentally benign route was developed for the preparation of 14-aryl or alkyl-14H-dibenzo[a,j]xanthene, 1,8-dioxo-octahydroxanthene and 12-aryl.
Abstract: A simple, efficient, and environmentally benign route was developed for the preparation of 14-aryl or alkyl-14H-dibenzo[a,j]xanthene, 1,8-dioxo-octahydroxanthene and 12-aryl—8,9,10,12-tetrahydrobenzo[a]xanthene-11-ones from condensation of various aldehydes with (i) β-naphthol, (ii) cyclic 1,3-dicarbonyl compounds and (iii) β-naphthol and cyclic 1,3-dicarbonyl compounds, using novel polymeric catalyst [poly(AMPS-co-AA)] under solvent-free conditions. Use of easily available catalyst, shorter reaction times, better yields, simplicity of the reaction, heterogeneous system, and easy work-up are the advantages of the present method.
TL;DR: A novel red fluorescent dye, 2Me SiR600 (λ(em)=613 nm), in which the O atom of Rhodamine Green at the 10 position of the xanthene moiety is replaced with a Si atom, is developed as a scaffold for probes to detect protease activity with extremely high S/N ratio.
TL;DR: Noble-metal-free systems with bio-inspired diiron dithiolate mimics of the [FeFe]-hydrogenase active site and photoinduced electron transfer was studied for visible-light-driven water reduction to hydrogen, showing good catalytic activities with the efficiencies in hydrogen evolution.
Abstract: Noble-metal-free systems with bio-inspired diiron dithiolate mimics of the [FeFe]-hydrogenase active site, namely, [(μ-pdt)Fe(2) (CO)(5) L] [pdt=propanedithiolate; L=P(CH(2) OH)(3) (1), P(CH(3) )(3) (2)], as water reduction catalysts with xanthene dyes as photosensitizers and triethylamine as a sacrificial electron donor were studied for visible-light-driven water reduction to hydrogen. These systems display good catalytic activities with the efficiencies in hydrogen evolution of up to 226 turnovers for 1, if Eosin Y was used as the photosensitizer in an environmentally benign solvent (EtOH/H(2) O) after 15 h of irradiation (λ>450 nm) under optimal conditions. Under all of the conditions adopted, 1 that has a water soluble phosphine ligand, P(CH(2) OH)(3) displayed a higher efficiency than 2, which bears a PMe(3) ligand. The photoinduced electron transfer in the systems was studied using fluorescence, transient absorption, time-resolved UV/Vis, and in situ electron paramagnetic resonance (EPR) spectroscopy. A new electron-transfer mechanism is proposed for hydrogen evolution by these iron-based photocatalytic systems.
Patent•
29 Aug 2012TL;DR: In this paper, a multimer structure of a specific xanthene derivative which is capable of providing a printed matter having further improved in performances concerning image fastness such as ozone resistance, light fastness and the like.
Abstract: An object of the invention is to provide a novel compound having a multimer structure of a specific xanthene derivative which is capable of providing a printed matter having further improved in performances concerning image fastness such as ozone resistance, light fastness and the like. A compound represented by formula (1): in formula (1), L represents a divalent to tetravalent linking group; D represents a residue obtained by removing 1 to 5 hydrogen atoms from a compound represented by formula (2); m represents an integer of 1 to 10, however, each L may be the same with or different from every other L; n represents an integer of 2 to 10, however, each D may be the same with or different from every other D; and in formula (2), each of R4 to R24 independently represents a hydrogen atom or a substituent, provided that formula (2) has at least one or more ionic hydrophilic groups.
TL;DR: In this paper, a 2-aminopyridine glycidyloxypropyl derivative as anchoring ligand was used in photodegradation experiments of rhodamine B under aerobic conditions.
Abstract: MCM-41 based materials were prepared with immobilized Mo II and Mo VI active sites based on [MoI 2 (CO) 3 ] and [MoO 2 Cl 2 ] cores, respectively, using a 2-aminopyridine glycidyloxypropyl derivative as anchoring ligand. Suitable characterization by powder X-ray diffraction, FTIR and, 13 C and 29 Si solid state NMR spectroscopy was accomplished. All new materials were successfully used in photodegradation experiments of rhodamine B under aerobic conditions. Control experiments using neat MCM-41 and direct photolysis of rhodamine B were also carried out. All experiments were run without any external source of oxygen other than air. Photocatalytic results show that the presence of Mo and its oxidation state is not innocent in this process. In addition, Mo catalysts act most probably by quenching rhodamine B excited state leading to extended degradation of the dye, through secondary photochemistry, beyond a simple de-ethylation process. Density functional theory (DFT) results corroborate with this showing that when rhodamine B is in excited state the xanthene moiety bond orders change.
TL;DR: The ability to cause the leakage of K+ from erythrocytes was associated with dye‐induced morphological changes, forming a crenated form from the normal discoid.
Abstract: We analyzed the photoinactivation of the membrane functions of bacteria and erythrocytes induced by xanthene dyes. The dyes tested were rose bengal, phloxine B, erythrosine B and eosin B. These dyes induced the leakage of K(+) from Staphylococcus aureus cells within minutes of photoirradiation, in the order of rose bengal > phloxine B > erythrosine B > eosin B. The ability of dyes to inhibit respiration was weak, except for rose bengal, and the dyes dissipated the membrane potential in similar time traces with changes in K(+) permeability. The xanthene dyes also induced the leakage of K(+) from bovine erythrocytes upon photoirradiation in the same order as that observed with bacteria. Furthermore, we found that the ability to cause the leakage of K(+) from erythrocytes was associated with dye-induced morphological changes, forming a crenated form from the normal discoid. These results are discussed in connection with the ability of xanthene dyes to generate singlet oxygen and bind to bacterial cells, and further compared with the actions of cationic porphyrins, which induced photoinactivation of bacteria through respiratory inhibition.
TL;DR: In this article, the commercial catalyst Amberlyst-15, an inexpensive, safe to handle and easy to recycle sulfonic resin, was used for the oxidative coupling of xanthene and thioxanthene with methylene active compounds.
TL;DR: In this paper, the authors described a one-pot condensation of aldehydes, 2-hydroxynaphthalene-1,4-dione, and 2-n...
Abstract: Facile and convenient procedures for the synthesis of dibenzo[a,i]xanthene-diones have been described. The process employs one-pot condensation of aldehydes, 2-hydroxynaphthalene-1,4-dione, and 2-n...
TL;DR: In this paper, a simple and convenient procedure for the synthesis of xanthene derivatives is described through a one-pot condensation of 2-naphthol with aryl aldehydes in the presence of poly(4-vinylpyridinium)hydrogen sulfate as an efficient, cheap, easily synthesised and eco-friendly catalyst under solvent free conditions.
TL;DR: In this article, the iodine catalyzed one-pot regioselective synthesis of p- condensed xanthenes was described as the key point of transformation, which provided an efficient access to five skeletally diverse scaffolds in excellent yields.
TL;DR: In this paper, the standard molar enthalpies of formation of xanthydrol, 9-xanthenecarboxylic acid and 9-texanthencarboxamide, in the gaseous state, at T =298.15 K, were determined by experimental and computational studies.
TL;DR: In this article, a new procedure was proposed for the synthesis of 1,8-dioxo-octahydroxanthenes from aromatic aldehydes and dimedone/1,3-cyclohexadione in aqueous medium.
Abstract: Hydrotrope induced synthesis of 1,8-dioxo-octahydroxanthenes from aromatic aldehydes and dimedone/1,3-cyclohexadione in aqueous medium is reported. The remarkable features of the new procedure are high conversions, shorter reaction times, cleaner reaction profiles, and simple experimental and work-up procedures.
TL;DR: An efficient one-pot condensation of β-naphthol, aldehydes, and cyclic 1,3-dicarbonyl compounds has been achieved with molecular iodine as a catalyst, thus a variety of tetrahydrobenzo [a]xanthene-11-one and diazabenzo[a]anthracene-9,11-dione derivatives were prepared in good yields.
Patent•
16 Mar 2012
TL;DR: In this paper, the authors proposed a Tetracyclic Xanthene Derivatives of Formula (I) and pharmaceutically acceptable salts thereof, wherein A, Y1, Y2, Z, Ra, Rb, R 1a, R1b and R2 are as defined herein.
Abstract: The present invention relates to novel Tetracyclic Xanthene Derivatives of Formula (I) and pharmaceutically acceptable salts thereof, wherein A, Y1, Y2, Z, Ra, Rb, R1a, R1b and R2 are as defined herein. The present invention also relates to compositions comprising at least one Tetracyclic Xanthene Derivative, and methods of using the Tetracyclic Xanthene Derivatives for treating or preventing HCV infection in a patient.