Effect of NaCl on the binding constant of styryl pyridinium dyes in anionic surfactant system

► The binding constant of styryl pyridinium dyes (1) in ground and excited state has been investigated in SDS in the presence and absence of NaCl. ► Larger binding constant of the dyes in the excited state explained in terms of flexibility of dyes in excited state. ► The highest binding constant value for C12 is attributed to the compatibility of the hydrophobic chain of both the surfactant and the dye.