Showing papers on "Xanthene published in 1975"
TL;DR: Intermolecular hydrogen bonding effects on internal conversion and intersystem crossing in 6-hydroxy-9-phenyl-fluoron and fluorescein were determined from fluorescence and triplet yield measurements in alkaline solutions of CF3CH2OH, H2O, CH3OH, CH 3CH2O and CH 3SOCH3.
150 citations
TL;DR: In this paper, a biphotonic pulsed laser excitation was used to obtain the upper excited singlet states in three xanthene dyes, and it was shown that the observed spectra depend on the nature and timing of the excitation frequencies.
43 citations
TL;DR: Lethal dye-sensitized photooxidation reactions in the black imported fire ant, Solenopsis richteri (Forel), have been defined as a function of whole body concentrations of a series of xanthene dyes.
Abstract: Lethal dye-sensitized photooxidation reactions in the black imported fire ant, Solenopsis richteri (Forel), have been defined as a function of whole body concentrations of a series of xanthene dyes. Log probit analysis of mortality data has allowed calculation of LD50 values of 1.1×10−3M for dietary levels and 2.3×10−7 moles/ gm wet weight for whole body concentrations of rose bengal in ants illuminated with 3800 μW/cm2 light for 4 h. Comparative LT50 values were calculated for the xanthene dye series and related to whole body dye concentrations.
16 citations
Patent•
27 Feb 1975TL;DR: The persistence of polymer carbanions created by such catalysts makes possible the controlled preparation of a variety of polymers, including block copolymers as discussed by the authors, which is useful in initiating anionic growth-type polymerization of monomers, such as alkylene oxides and vinyl compounds.
Abstract: Organometallic compounds of high carbanion yield are prepared by metallation with barium, strontium or calcium or mixture of the same of certain acidic organic compounds having a pKa value of between about 15 and 35 on the MSAD scale in the presence of aprotic polar solvents, e.g., barium reacted with xanthene in 1,2-dimethoxyethane to yield dixanthenyl barium. Such organometallic compounds formed by metal-hydrogen exchange reaction are useful in initiating anionic growth-type polymerization of monomers, e.g., alkylene oxides and vinyl compounds, to form homopolymers and copolymers. The persistence of polymer carbanions created by such catalysts makes possible the controlled preparation of a variety of polymers, including block copolymers.
4 citations
Patent•
18 Dec 1975
TL;DR: Aryllamines of formula (I): Z-NR1R2 (where Z is of formula and r 1-4 are aliphatic radicals, opt. the same; R 1,3,4 can be H, and/or R 4 can be alkoxy) are prepd. by reacting a prim. or sec. amine of formula H-NR 1R2 with a phenol of formula Z-OH, in the presence of a carboxylic acid as mentioned in this paper.
Abstract: Aryllamines of formula (I): Z-NR1R2 (where Z is of formula and r1-4 are aliphatic radicals, opt. the same; R1,3,4 can be H, and/or R4 can be alkoxy) are prepd. by reacting a prim. or sec. amine of formula H-NR1R2 with a phenol of formula Z-OH, in the presence of a carboxylic acid. Cpds. (I) are useful as inters. for plant protection agents, optical brighteners, partic. aminocoumarins and dyes of xanthene, pyronine, rhodamine, oxasine series, azo dyes and dephenylmethane and triphenylmethane dyes. Simple economic process giving good yields of pure prod. The process does not leave residual tars or form N,N'-disubstd. meta-phenylenediamines, does not corrosive conditions or reagents, forms few pollutants and avoids use of high pressure and temp.
1 citations
TL;DR: In this paper, the authors show that the generation of charge carriers is not a primary process but seems to occur because of two-exciton mechanism, one formed by light absorption and the other (Mott exciton) due to hyperelectronic polarization.
Abstract: Bulk photoconductivity and dielectric constant of xanthene organic polymer under voltage ((100÷800) V) and temperature ((30÷120) °C) variations show that generation of charge carriers is not a primary process but seems to occur because of two-exciton mechanism, one formed by light absorption and the other (Mott exciton) due to hyperelectronic polarization.
1 citations
Journal Article•
1 citations
TL;DR: In this article, the spectral data and chemical reactions of the lactone are compatible with the structure of the 2-Acyl-3-methyl-1,4-naphthoquinone-2,3-epoxide.
Abstract: 2-Acyl-3-methyl-1,4-naphthoquinone-2,3-epoxide(1) isomerizes photochemically to give lactone. The spectral data and chemical reactions of the lactone are compatible with structure(2). Photochemical reaction of (1) with xanthene was also described.