Showing papers on "Xanthene published in 1993"
TL;DR: In this paper, the photophysical properties and photobleaching of the xanthene dye merbromin (MR) and the production and quenching of singlet molecular oxygen, O2(1Δg), were investigated in aqueous solutions.
Abstract: The photophysical properties and photobleaching of the xanthene dye merbromin (MR), and the production and quenching of singlet molecular oxygen, O2(1Δg), were investigated in aqueous solutions, in comparison with the xanthene dyes eosin (Eos) and rose bengal (RB). MR photobleaches in the absence of O2 in a process involving the solvent (H2O or alcohols). No participation of O2·− or O2(1Δg) could be established in the presence of O2, although O2 was consumed. In aqueous and alcoholic solutions, MR forms ground state, charge transfer (CT) complexes with biologically relevant electron-donor amino acids, such as histidine and tryptophan, and other indolic derivatives. These complexes are formed with relatively high association constants (3×103−5×103) and are mainly responsible for the photobleaching of MR and the amino acids in these solutions by a mechanism involving O2(1Δg) generated probably by an excited state of the CT complex. MR generates O2(1Δg) with a relatively high yield (ΦΔ=0.23±0.04) and quenches O2(1Δg) only physically with kq=(2.3±0.05)×108 M−1 s−1. This process does not affect the photosensitizing ability of MR under the low concentrations needed for its action. Non-donor compounds such as the amino acid methionine and linoleic acid methyl ester are photodegraded by a type II mechanism without implication of a dye CT complex.
33 citations
TL;DR: In this article, the system of various xanthene dyes in diffusionless weakly polar electron donating solvents was discussed for the system for ultrafast intermolecular electron transfer (ET), which is determined by mutual displacement of the reactants and by the solvent relaxation.
Abstract: Ultrafast intermolecular electron transfer (ET) is discussed for the system of various xanthene dyes in diffusionless weakly polar electron donating solvents. ET was observed by fluorescence quenching dynamics. It gives a non-exponential process in case of dyes in aniline. ET rate is determined by mutual displacement of the reactants and by the solvent relaxation. In case of dyes in N,N-dimethylaniline, ET quenching gives very different dynamics and shows a single exponential decay with a rate constant as fast as 1013 s-1. Ultrafast ET, which is much faster than solvent relaxation time, requires a new mechanism for a cause of ET.and its rate constant may be determined by nuclear motion, rather than controlled by solvent dynamics.
23 citations
TL;DR: All spectral and kinetic variations of the chemiluminescence from the IAA/HRP/O2 system which are caused by the addition of xanthene dyes, are the result of IAA‐dye co‐oxidation.
21 citations
TL;DR: In this paper, the lipophilicity of 9 H -xanthene and 9 H-thioxanthene derivatives, containing either a basic alkanamide or a nitrosoureido group, was studied by means of reversed-phase high-performance liquid chromatography using an octadecylsilane stationary phase, methanol as organic modifier and n -decylamine as masking agent.
15 citations
TL;DR: In this paper, the 9-methylanthryl esters of three xanthene dyes, erythrosine, phloxine, and rose bengal, have been synthesized.
Abstract: The 9-methylanthryl esters of three xanthene dyes, erythrosine, phloxine, and rose bengal, have been synthesized. Flash photolysis and transient absorption measurements at 600 nm (xanthene triplet state) and 435 nm (anthryl triplet state) have been used to determine that intramolecular triplet-triplet energy transfer is highly efficient in two of these esters but is only partial in the ester of rose bengal. These results demonstrate that the triplet states of erythrosine and phloxine lie higher in energy, while the triplet state of rose bengal is close to but lower in energy, than that of the anthryl moiety.
14 citations
TL;DR: The 9,10-dimethylacridium cation with 4-nitroso-N,N-dialkylanilines gives highly bathochromic azacyanines in good yields as discussed by the authors.
11 citations
TL;DR: In this article, it was shown that the equilibrium conformation of xanthene is nonplanar in the ground state and planar in lowest excited singlet state, and the estimated ground state inversion barrier is 50 cm−1.
Abstract: The analyses of fluorescence excitation and dispersed fluorescence spectra of jet‐cooled xanthene indicate that the equilibrium conformation of the molecule is nonplanar in the ground state and planar in the lowest excited singlet state. The estimated ground‐state inversion barrier is 50 cm−1.
11 citations
TL;DR: Treatment of either p-tert-butylcalix[4]arene (3), xanthene or 9,10 dihydroanthracene with diphenyl ether in the presence of Nafion-H results in the formation of [9,9]spirobixanthene (5).
9 citations
TL;DR: In this paper, the time constant of a decaying phase-conjugate signal was measured as a function of a grating period in polyvinyl alcohol films doped with xanthene dyes such as erythrosin B, eosin Y, and uranin.
Abstract: The time constant of a decaying phase-conjugate (PC) signal was measured as a function of a grating period in polyvinyl alcohol films doped with xanthene dyes such as erythrosin B, eosin Y, and uranin. The time constant was independent of the grating period and was of the same order as the time required for the population grating of each dye to decay. These experimental results indicated that there was a population grating contribution but not a thermal grating contribution in the generation of PC signals by these saturable xanthene-dye films.
8 citations
TL;DR: In this paper, the antioxidant properties of 9H-xanthene-2,7-diols were evaluated by means of an oxygen-absorption method at 60 °C for tetralin.
Abstract: The antioxidant activities of 9H-xanthene-2,7-diols were evaluated by means of an oxygen-absorption method at 60 °C for tetralin. Very good activities were observed for 1,3,4,5,6,8-hexamethyl-9H-xanthene-2,7-diol and 1,3,4,5,6,8,9-heptamethyl-9H-xanthene-2,7-diol.
8 citations
Patent•
26 Jan 1993
TL;DR: An ink containing less than 5% inorganic compounds which comprises a liquid medium and a dye of the Formula (1) is an ink which can be used in ink jet printing either alone or with specified xanthene dyes as discussed by the authors.
Abstract: An ink containing less than 5% inorganic compounds which comprises a liquid medium and a dye of the Formula (1): ##STR1## wherein: D1 and D2 are each independently a chromophore of the azo series; R1, R2, R3 and R4 are each independently H or optionally substituted alkyl; B is a labile atom or group, hydroxy, amino or an ether, thioether or amine group; and X1 and X2 are each independently H, halo, alkyl, alkoxy, acylamino, ureido, nitro, carboxy or sulpho. The inks may be used in ink jet printing either alone or with specified xanthene dyes.
TL;DR: In this paper, the transient phenomena in a laser flash photolysis study of a new series of xanthene dyes in ethanol solution at room temperature were described, and the difference between the triplet- and ground-state absorption spectra of tetrabromohydrofluorescein (TBHF) or tetraiodohydro-fluorescellin (TIHF) showed peaks around 360 and 580 nm.
Abstract: The transient phenomena in a laser flash photolysis study of a new series of xanthene dyes in ethanol solution at room temperature are described. The difference between the triplet- and ground-state absorption spectra of tetrabromohydrofluorescein (TBHF) or tetraiodohydrofluorescein (TIHF) shows peaks around 360 and 580 nm. Tetrabromohydrocyanofluorescein (TBHCF) and tetraiodohydrocyanofluorescein (TIHCF) demonstrate triplet-triplet absorption with peaks around 340 and 460 nm. The corresponding anion radicals D .- , which are produced by electron-transfer reactions from aromatic amina, have absorption maxima at 410 nm
TL;DR: Pyrido as discussed by the authors, which can be regarded as a combined structure of a xanthene analog and quinoline, was synthesized starting from 6-amino-5H-[1]benzopyrano[2, 3-b]pyridin-5-one (2).
Abstract: Pyrido[3', 2' : 5, 6]pyrano[4, 3, 2-de]quinoline (1), which can be regarded as a combined structure of a xanthene analog and quinoline, was synthesized starting from 6-amino-5H-[1]benzopyrano[2, 3-b]pyridin-5-one (2).
01 Jan 1993
01 Jan 1993
Patent•
07 Dec 1993
TL;DR: In this article, a xanthene derivative was used as leuco dye and the following formulas were given: R and R are independently hydrogen atom, alkyl, aralkyl, aryl, halogen atom, alkoxyl, polycyclic compd, trifluoromethyl, substituted carbonyl or substituted sulfonyl.
Abstract: PURPOSE:To obtain a picture forming material imparting a black image reduced in fogging before use, enhanced in density of colored picture and excellent in stability in the picture forming material with a coating layer contg. an oxidation-reduction mixture consisting of leuco dye, acidic material, photooxidative agent, polycyclic compd. and hydrogen donor as the essential components formed on a support by using a specified xanthene derivative as the leuco dye. CONSTITUTION:A xanthene derivative shown by the formula is used as leuco dye. In the formula, R and R are independently hydrogen atom, alkyl, aralkyl or aryl, R is hydrogen atom, alkyl, aralkyl, aryl, halogen atom, alkoxyl, aryloxy group, alkylthio group or arylthio group, R and R are independently hydrogen atom, alkyl, alkoxyl, halogen atom, trifluoromethyl, substituted carbonyl or substituted sulfonyl, and R is hydrogen atom, alkyl or substituted carbonyl.
TL;DR: Treatment of either p-tert-butylcalix[4]arene (3), xanthene or 9,10 dihydroanthracene with diphenyl ether in the presence of Nafion-H results in the formation of [9,9]spirobixanthene (5).
Abstract: Treatment of either p-tert-butylcalix[4]arene (3), xanthene or 9,10 dihydroanthracene with diphenyl ether in the presence of Nafion-H results in the formation of [9,9]spirobixanthene (5).
TL;DR: Fluorescence polarization and EPR spectroscopy were performed on the labeled fibers in rigor and both signals indicate a highly ordered system characteristic of cross-bridges bound to actin.
Abstract: Several unsubstituted xanthene dyes (eosin, erythrosin, and fluorescein) were irradiated by laser light at their absorption maximum in the presence of different reducing agents. Due to photochemical reduction the quinoidal structure of the xanthene ring is transformed into a semiquinone and a π-radical is formed having a characteristic electron paramagnetic resonance (EPR) signal of an unpaired electron spin with proton hyperfine interactions. A strong EPR signal is observed from the dye in solution or when specifically attached to myosin following irradiation in the presence of dithiothreitol or cysteine. The spectroscopic methods of fluorescence polarization and EPR are useful in the study of ordered biological assemblies. These methods generate complementary information about the order of the system but a consistent quantitative interpretation of the related data is complicated because the signals arise from different donors. Our method allows us to detect both signals from the same donor. We applied our new technique to the study of skeletal muscle fibers. The fluorescent dye iodoacetamidofluorescein was covalently attached to the reactive thiol of the myosin molecule in muscle fibers. Fluorescence polarization and EPR spectroscopy were performed on the labeled fibers in rigor. Both signals indicate a highly ordered system characteristic of cross-bridges bound to actin.
TL;DR: In this paper, it was shown that the equilibrium conformation of xanthene is nonplanar in the ground state and planar in lowest excited singlet state, and the estimated ground state inversion barrier is 50 cm−1.
Abstract: The analyses of fluorescence excitation and dispersed fluorescence spectra of jet‐cooled xanthene indicate that the equilibrium conformation of the molecule is nonplanar in the ground state and planar in the lowest excited singlet state. The estimated ground‐state inversion barrier is 50 cm−1.
Patent•
21 Jan 1993TL;DR: In this paper, the authors present a method to detect chemical warfare agents using a fluorescent reagent (II), the fluorescent emission of which changes in contact with (I) when the reagent is dissolved or dispersed in a solvent with which it is immiscible.
Abstract: Detection of chemical warfare agent(s) (I) involves the use of a fluorescent reagent (II), the fluorescent emission of which changes in contact with (I). The novel features are that, for (II): a) the values of the log of the acid constant in the electronic ground state and in the excited state capable of emiss-ion differ by more than 2; b) the emission wavelength of the pro-tolytic form in an organic solvent is different from that in water; and c) (II) is dissolved or dispersed in a solvent with which (I) is immiscible.(II) is highly soluble in organic solvents and forms only a disp-ersion of undissolved solid in water. The solvent or dispersant used is a hardly flammable mixt. of water with max. 20% organic solvent, which is 1 x 10-3 to 1 x 10-2M in (II). (II) pref. is 6-aminoquinoline (IIA), 'Fluorol 086' (RTM; 2-butyl-6-butylamino-2,3- dihydro-1H-benz(de) isoaquinolin-1,3-dione, (IIB)) or Fluorol 088' (RTM; 2,8-dimethyl- naephtho(3,2,1-k1)xanthene)