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

The fluorescence response to pH of 2,4 dinitrophenolhydrazone in 1:1 CH₃OH:H₂O and micellar mediums—negatively charged sodium dodecylsulphate (SDS), positively charged cetyltrimethyl ammonium bromide (CTAB) and neutral Triton X-100 (TX-100), is reported. At pH 4.0 the fluorescence of the molecule can be switched “on” by selecting CTAB as the solvent. At pH 6.0 if the medium is TX-100 the fluorescence is “off”, but remains “on” for the other three solvents. At pH 8.0, fluorescence is “on” in the solvents except CTAB. SDS and TX-100 switch the fluorescence “on” at pH 13.0 but for the other two solvents the fluorescence is “off”.