Search results for "Fluorescence"
showing 3 items of 2463 documents
Ortho -Functionalized Aryltetrazines by Direct Palladium-Catalyzed C−H Halogenation: Application to Fast Electrophilic Fluorination Reactions
2016
International audience; A general catalyzed direct C-H functionalization of s-tetrazines is reported. Under mild reaction conditions, N-directed ortho-C-H activation of tetrazines allows the introduction of various functional groups, thus forming carbon-heteroatom bonds: C-X (X=I, Br, Cl) and C-O. Based on this methodology, we developed electrophilic mono- and poly-ortho-fluorination of tetrazines. Microwave irradiation was optimized to afford fluorinated s-aryltetrazines, with satisfactory selectivity, within only ten minutes. This work provides an efficient and practical entry for further accessing highly substituted tetrazine derivatives (iodo, bromo, chloro, fluoro, and acetate precurso…
Nepārtraukta starojuma lāzera ietekme uz ādas autofluorescences dzīves laiku
2015
Ar spektroskopijas metodēm (ādas autofluorescences ierosināšana un emisijas spektru novērošana) nav iespējams izšķirt spektru veidojošās komponentes. Ar laikā izšķirtu spektroskopiju iegūtos datus aproksimējot ar trīs komponentēm un apstrādājot ar metodēm TRES un TRANES, ir iespējams izšķirt spektru veidojošas komponentes un novērot nepārtraukta lāzerstarojuma ietekmi uz komponenšu dzīves laikiem. Autofluorescences dzīves laiki var mainīties – pieaugt vai samazināties - atkarībā no apstarošanai izmatotā viļņa garuma un izvēlēta diapazona. Izmantojot TRANES apstrādes metodi, pēc fotoizbalēšanas tika novērota emisijas maksimuma nobīde, kas liecina par fluoroforu sadalījuma izmaiņu fotoizbalēš…
Ground and first excited electronic state interaction of FAD with some β-carboline derivatives
1987
Abstract The spectrophotometric and thermodynamic properties of molecular complexes of flavine adenine dinucleotide (FAD) with some dihydro β-carboline derivatives have been investigated in aqueous solution. The molecular associations have been examined by means of electronic absorption spectra, since in each a new charge-transfer band has been located, and also the variation of the fluorescence emission of FAD on the solutions has been observed. The formation constants for the molecular complexes were determined from absorption data, using the Foster-Hammick-Wardley method. The quenching fluorescence phenomena observed in FAD is related to the concentration of the dihydro β-carboline deriv…