title: Syntheses and properties of water-soluble Nile Red derivatives.
abstract: Nile Red (compound A) fluoresces at about 530 nm with good quantum yields in apolar solvents. In more polar ones its fluorescence emission shows a dramatic, and potentially useful, shift to about 640 nm, but its quantum yield is significantly reduced. Further, Nile Red has a very poor solubility in aqueous media. The hypothesis tested in this paper is that Nile Red derivatives that incorporate water-solubilizing groups will tend to fluoresce with good quantum yields in aqueous media, and in the more useful wavelength range around 640 nm. Thus three Nile Red derivatives, 1-3, were prepared. Compound 1 had three hydroxyl groups more than Nile Red, but was surprisingly insoluble in aqueous media. However, the dicarboxylic acid 2 and carboxylic/sulfonic acid derivative 3 showed excellent water solubilities. Spectral data for 2 and 3 showed that they do indeed fluoresce with good quantum yields in the 640 nm region in aqueous media. These properties of compounds 2 and 3 might be useful in the development of fluorescent probes for biotechnology.
authors.affiliation: Department of Chemistry, Texas A&M University, Box 30012, College Station, Texas 77841, USA.
authors.forename: Jiney
authors.initials: J
authors.lastname: Jose
authors.forename: Kevin
authors.initials: K
authors.lastname: Burgess
mesh_terms: D005453:Fluorescence; D010078:Oxazines / Q000138:chemical synthesis* / Q000737:chemistry; D012995:Solubility; D014867:Water
chemical_list: D010078:Oxazines; D014867:Water; C044808:nile red