Significant effect of surfactant micelles on pH dependent fluorescent off-on-off behavior of Salicylaldehyde-2,4-Dinitrophenylhydrazone

► The fluorescence response to pH of Salicylaldehyde-2,4 Dinitrophenolhydrazone in 1:1 CH3OH:H2O and in positively charged cetyltrimethyl ammonium bromide (CTAB) micellar medium shows “off-on-off” behavior. ► In negatively charged sodium dodecylsulphate (SDS) the response of fluorescence of Salicylaldehyde-2,4 Dinitrophenolhydrazone to pH is “off-on-on” type while in neutral Triton X-100 it is “off-on-1/2on” type. ► At a given pH, fluorescence of 2,4 dinitrophenolhydrazone can be made “on” or “off” by selecting an appropriate pH.