Rhodamine

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Structural formula of rhodamine B
( 9- (2-carboxyphenyl) -3,6-bis (diethylamino) xanthylium chloride )
Structural formula of rhodamine 6G
Rhodamine 123 ( hydrochloride )
Absorption, fluorescence excitation and fluorescence emission spectrum of a solution of the dye rhodamine 6G.

Rhodamines are fluorescent dyes from the group of cationic dyes . The structure of the rhodamines is derived from xanthene . They are both a subgroup of xanthene dyes and triphenylmethane dyes . The most famous representatives are u. a. Rhodamine 6G, Rhodamine B , Rhodamine 123, Texas Red ( Sulforhodamine 110 ), 5-TAMRA , 5-TAMRA-SE, and TMRM + . Depending on the structure, rhodamines fluoresce from the yellow-green to the orange-red spectral range.

Most rhodamines, like many laser dyes, have a quantum yield close to 100%. The quantum yield is strongly dependent on the solvent and is z. B. 95% for Rhodamine 6G in ethanol , i.e. H. of 100 photons absorbed , 95 are converted into fluorescence photons . Furthermore, the probability of a spin flip (from the singlet state to the triplet state) is very low, so that rhodamines are rarely in the long-lived triplet state in which they do not fluoresce.

use

Rhodamines are used, among other things, as dyes for paper and textiles, in luminous pigments, in dye lasers , and in cell and molecular biology ( TRITC ), where they are used e.g. B. serve as a marker or label for fluorescence microscopy and single molecule fluorescence spectroscopy . In the past, rhodamines were also used as dyes for hydrogeological dyeing experiments . Nowadays, however, this is not done because rhodamines are classified as potentially carcinogenic , mutagenic and ecotoxic : Rhodamine B is acutely toxic to animal aquatic organisms such as daphnia at concentrations of 100 mg / l . However, rhodamine B, especially when chemically pure, is somewhat less mutagenic and mutagenic than rhodamine 6G.

Individual evidence

  1. ↑ Douglas Magde, Roger Wong, Paul G. Seybold: Fluorescence Quantum Yields and Their Relation to Lifetimes of Rhodamine 6G and Fluorescein in Nine Solvents: Improved Absolute Standards for Quantum Yields. In: Photochemistry and Photobiology. Volume 75, Issue 4, 2002, pp. 327-334.
  2. ↑ Alexander P. Demchenko (Ed.): Advanced Fluorescence Reporters in Chemistry and Biology I: Fundamentals and Molecular Design (Springer Series on Fluorescence) . Springer, Berlin, Heidelberg 2010, ISBN 978-3-642-04700-8 , pp. 49 ff . ( limited preview in Google Book search).
  3. ↑ Werner Käß , Horst Behrens: Tracing technique in geohydrology . AA Balkema Publishers, Rotterdam 1998, ISBN 978-90-5410-444-5 , pp. 18th ff . ( limited preview in Google Book search).
  4. ^ A. Kranjc (Ed.): Tracer Hydrology 97: Proceedings of the 7th International Symposium on Water Tracing . AA Balkema Publishers, Rotterdam 1997, ISBN 978-90-5410-875-7 , pp. 71 ff . ( limited preview in Google Book search).
  5. ↑ P. Brandt: Reports on food safety. Federal Office for Consumer Protection and Food Safety 2005, page 8.
  6. ↑ ER Nestmann, GR Douglas, TI Matula, CE Grant, DJ Kowbel: Mutagenic activity of rhodamine dyes and their impurities as detected by mutation induction in Salmonella and DNA damage in Chinese hamster ovary cells. In: Cancer Research . Volume 39, Number 11, November 1979, pp. 4412-4417, PMID 387214 . (PDF) .

Web links

Absorption and emission spectrum (solvent ethanol) of: