The spectroscopic and fluorometric properties of nine oxacyanine dyes (3,3'-dimethyloxacarbocyanine through 3,3'-diheptyloxacarbocyanine, 3,3'-diethyl-, and 3,3'-dipropyloxadicarbocyanine iodides) were determined in two solvents, water and nitrobenzene. In nitrobenzene the absorbance and fluorometric spectra of the dyes showed a red shift of 15 to 20 nm when compared with the spectra in water. In addition, the fluorescence emission intensity of the dyes is lower in nitrobenzene than in water, by one to two orders of magnitude. Thus it is possible to measure fluorescence in water in water/nitrobenzene systems without interference from the nitrobenzene part. The molar absorptivities of the dyes were calculated and used to determine the solubility of the dyes in water and the partition coefficients of the dyes between nitrobenzene and water. These dyes were characterized in order to provide a better understanding of the properties of the dyes in a water/nitrobenzene interface system which will be used in electrochemical studies of the dyes.
Deborah H. Wiegand and Petr Vanýsek, "Spectroscopic and Fluorometric Characterization of Oxacyanine Dyes in Water and Nitrobenzene," Appl. Spectrosc. 42, 958-961 (1988)