Xanthamide fluorescent dyes.
Two derivatives of fluorescein, termed "xanthamides," were prepared from fluorescein, an inexpensive dye. Relative to fluorescein, which contains a 6-phenolic OH and a 2'-carboxyl, the first derivative (5) contains a carboxymethyl ether at the 6-position and a secondary amide of dimethylamine at the 2'-position. The second derivative (8) contains a corresponding 6-methyl ether and a secondary amide of isonipecotic acid at the 2'-position. Thus, both derivatives contain a single carboxyl group, making them monofunctional. Especially 8 is much more photostable (about 10 times) than either fluorescein or BODIPY FL dye when exposed to ordinary light (tungsten light bulb). When tested for relative response in a capillary electrophoresis instrument fitted with an argon ion laser detector (488 nm) and a broad band emission filter, 8 was found to be 4-fold less bright than fluorescein. Both xanthamides, consistent with prior literature on 6-O-alkylated fluorescein, exhibit relatively pH-independent fluorescence (pH 4-10 was tested here). Because they possess two absorbance maximums, the xanthamides can be excited over a broader wavelength range than fluorescein or BODIPY. These collective properties of the xanthamides will make them advantageous over fluorescein and BODIPY dyes for some applications.
Gao
Jianxin
J
Department of Pharmaceutical Sciences in the Bouve College of Pharmacy and Health Professions, Barnett Institute, Boston, Massachusetts 02115, USA.
Wang
Poguang
P
Giese
Roger W
RW
D001896:Boron Compounds / Q000737:chemistry; D019075:Electrophoresis, Capillary; D005452:Fluoresceins / Q000138:chemical synthesis* / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D015394:Molecular Structure; D013050:Spectrometry, Fluorescence
C120161:BODIPY FL hydrazide; D001896:Boron Compounds; D005452:Fluoresceins