EFFECT OF SALT AND SOLVENTS ON THE IONIC SOLVATION OF P-TOLUIDINONAPHTHALENE SULFONATE

Fluorescence properties of p-toluidinonaphthalene sulfonate (TNS) are studied in the presence of tetra-n-butylammonium bromide (TBBr) in dif ferent solvents. In the presence of TBBr, in solvents of low polarity (tetrahydrofuran, THF), the fluorescence decay of TNS at the blue end (395 nm) is distinctly faster than that at the red end (500 nm). This is attributed to the formation of ionic aggregates involving negativel y charged TNS and positively charged tetrabutylammonium ions. From the difference in the lifetimes at the red and blue ends, the ionic relax ation rates are obtained. In solvents of moderately high polarity (dim ethylformamide, DMF) no such aggregates are detected and the decay at the red end is very similar to that at the blue end. In highly polar a queous media, however, micellar aggregates of TBBr are formed, but the re is no difference in the decay at the red and blue ends. The micella r aggregates in aqueous media remain unaffected in the presence of 3 m ol dm(-3) urea.