ASYMMETRIC, WATER-SOLUBLE CYANINE DYES: SYNTHESIS AND FLUORESCENT PROBE FOR THE Fe3+ ION

Two known symmetric and four novel asymmetric water-soluble pentamethyl cyanine dyes were synthesized and fully characterized by IR, MS and NMR. These dyes exhibited good water solubility and possessed good stability at different pH environment. On the basis of investigation toward the change of U-vis absorption spectra under heat or illumination, these results indicated that the asymmetric cyanine dyes have better photo-thermal stability than that of symmetric dyes under the state of solution, which was also proved by the results of thermogravimetric analysis (TGA). Meanwhile, the researches on the fluorescent probes for metal ions detection demonstrated that the dyes can be considered as a fluorescent probe for detection of Fe3+ ion, and the anti-interference experiments displayed that the dye exhibits excellent selectivity towards Fe3+ ion over other common metal cations (Cr3+, Zn2+, Ni2+, Al3+, Mg2+, Cu2+).