Solvatochromic studies of fluorescent azo dyes: Kamlet-Taft (π*, α and β) and Catalan (S(pp), S(A) and S(B)) solvent scales approach.

A new metal ion-responsive azo-based fluorescent probes have been synthesized and characterized by NMR spectral techniques. Steady-state fluorometric study has been used to analyze the spectroscopic and photophysical characteristics of dye derivatives in various solvents. The fluorescence properties of these dyes are strongly solvent dependent, the wavelength of maximum fluorescence emission shifts to the red. The Kamlet-Taft and Catalan's solvent scales were found to be the most suitable for describing the solvatochromic shifts of the absorption and fluorescence emission. The hydroxy substituted azo dye formed complexes with several metal ions (Co(2+), Hg(2+), Ni(2+) and Cu(2+)) and fluorescence quenching with metal ions reveal that it can be used as a new fluorescence sensor to detect the Cu(2+) ion.