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Charge separation in photoredox reactions

Description: This report deals with the photoreduction of alkylmethylviologens in vesicles in which the combined effect of the alkylmethylviologen chain length and the addition of cholesterol to the vesicle system has been assessed. Although the alkyl chain length effect predominately controls the photoreduction yield it is shown that cholesterol addition can tune the magnitude of this effect. A series of neutral alkylphenothiazines has been synthesized and the effect of alkyl chain length in variously char… more
Date: October 1, 1991
Creator: Kevan, L.
Partner: UNT Libraries Government Documents Department
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Electron Transfer Reactions of Excited Dyes With Metal Complexes. Progress Report, March 1, 1978-February 28, 1979. [Iron-Methylene Blue]

Description: An intense absorption band of /sup 3/MBH/sup 2 +/ at 700nm was characterized in several media and its pK/sub A/ was measured to be 7.17 +- .1 in water. Flash photolysis show that semiethylene blue, MBH/sup +/, formed by quenching /sup 3/MBH/sup 2 +/ with Fe/sub II/(H/sub 2/O)/sub 6//sup 2 +/, decays by disproportionation at a diffusion-controlled rate. Rates of decay of the photostationary state of solutions of MB/sup +/ and Fe/sup II/(H/sub 2/O)/sub 6//sup 2 +/ in acidic media were measured us… more
Date: March 15, 1979
Creator: Lichtin, N. N.
Partner: UNT Libraries Government Documents Department
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Previously Unreported Intense Absorption Band and the pK/sub A/ of Protonated Triplet Methylene Blue

Description: Excitation by a Q-switched giant ruby laser (1.2 joule output at 694 nm, approx. 50 nsec flash) of 2-10 ..mu..M solutions of methylene blue in water, 30% ethanol in water or 50 v/v% water - CH/sub 3/CN at pH values in the range 2.0 - 9.3 converted the dye essentially completely to its T/sub 1/ state. The absorption spectrum of T/sub 1/ dye was measured in different media at pH 2.0 and 8.2 by kinetic spectrophotometry. Previously reported T-T absorption in the violet in acidic and alkaline solut… more
Date: January 1, 1979
Creator: Ohno, T.; Osif, T. L. & Lichtin, N. N.
Partner: UNT Libraries Government Documents Department
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Energy transfer mechanisms in photobiological reactions. Progress report, 1 August 1975--30 April 1976

Description: As in our earlier work on the sensitized photooxidation of substituted phenylalanines, ring substituents were found to have a marked effect on the photooxidation of uracil. This compound was selected as a typical pyrimidine for detailed studies of the mechanism of photooxidation of molecules of biological importance. The photooxidation of a series of 5-substituted uracils as sensitized by eosin Y, ruthenium bipyridyl, 3-methyl-lumiflavin and methylene blue was studied using oxygen electrode and… more
Date: April 30, 1976
Creator: Spikes, J. D.
Partner: UNT Libraries Government Documents Department
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Photoinduced Charge Separation in Linked Donor-Chromophore-Acceptor Systems. Progress Report, September 1, 1993--May 31, 1993

Description: Focus has been mainly on preparation and characterization of triply bridged dinuclear complexes containing a tris-2-2`- bipyridineruthenium chromophore and a second tris-bipyridine metal complex which is to serve as electron donor or acceptor, and of linked RuL{sub 3}-containing D-C-A complexes where D is a phenothiazine donor and A is a diquat type acceptor. (DLC)
Date: June 1, 1993
Creator: Elliott, C. M.
Partner: UNT Libraries Government Documents Department
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Mechanisms of immunosuppression and cellular mechanisms of secondary disease. Final report, September 1, 1971--August 31, 1973

Description: The development of antibody-producing cells was studied in vivo and in vitro using radiation, anti-tumor drugs, and antibiotics. The mechanism of action of phenothiazines was studied at the cellular level using a cell separation technique. The effects of puromycin and purine antimetabolites on the various development stages of cells were studied. (HLW)
Date: 1973-09~
Creator: Uyeki, Edwin M.
Partner: UNT Libraries Government Documents Department
open access

Photoinduced Charge Separation in Linked Donor-Chromophore-Acceptor Systems

Description: Focus has been mainly on preparation and characterization of triply bridged dinuclear complexes containing a tris-2-2'- bipyridineruthenium chromophore and a second tris-bipyridine metal complex which is to serve as electron donor or acceptor, and of linked RuL[sub 3]-containing D-C-A complexes where D is a phenothiazine donor and A is a diquat type acceptor. (DLC)
Date: June 1, 1993
Creator: Elliott, C.M.
Partner: UNT Libraries Government Documents Department
open access

Development of Unique Catalysts for Hydrodenitrogenation of Coal-Derived Liquids. Annual Report, September 15, 1979-September 15, 1980

Description: Hydrodenitrogenation of quinoline and decahydroquinoline has been studied employing several catalysts: Bronsted and Lewis acid catalysts without metal, and silica-alumina, ..gamma..-alumina and magnesia impregnated with molybdenum, tungsten, nickel or cobalt. Our results show that nitrogen removal rate was highest for molybdenum on alumina and tungsten on silica-alumina or alumina catalysts. Nitrogen abstraction using ..gamma..-alumina support is considerably faster than with magnesia support. … more
Date: December 15, 1980
Creator: Katzer, James R.; Stiles, Alvin B. & Kwart, Harold
Partner: UNT Libraries Government Documents Department
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Investigation of Molecular Mechanisms in Photodynamic Action and Radiobiology with Nanosecond Flash Photolysis and Pulse Radiolysis. Progress report, October 1, 1980-September 30, 1981

Description: Laser flash photolysis experiments have led to a new mechanism for the ultraviolet photolysis of aqueous tryptophan (Trp), indole (Ind) and certain indole derivatives. Excitation at 265 nm leads to photoionization via a pre-fluorescent state with thermal activation. A new formula is proposed for predicting enzyme inactivation quantum yields. The predictions are in good agreement with measurements on six important enzymes at 254 nm and 280 nm. Kinetics models have been developed and tested for i… more
Date: June 1, 1981
Creator: Grossweiner, Leonard I.
Partner: UNT Libraries Government Documents Department
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Charge Separation in Photoredox Reactions. Final Report

Description: The structural aspects controlling charge separation in molecular photoionization reactions in organized molecular assemblies involving micelles, reverse micelles and vesicles are being studied by optical and electron magnetic resonance techniques including the time domain technique of deuterium electron spin echo modulation (ESEM) and matrix proton electron nuclear double resonance (ENDOR) to measure weak electron-nuclear dipolar interactions. ESEM and matrix ENDOR are particularly well adapte… more
Date: July 15, 1993
Creator: Kevan, L.
Partner: UNT Libraries Government Documents Department
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