Surfactant Dependent pH Controlled "off-on", "off-on-off" and "on-off" Fluorescent Switches Exhibited by N-Benzylidenenaphthalen-1-Amine.

N-benzylidenenaphthalen-1-amine (L) acts as pH dependent "off-on", "off-on-off" and "on-off" fluorescent switch in 1:1 (v/v) CH3CN:H2O depending on the presence of anionic sodiumdocdecyl sulphate (SDS), neutral triton X-100 (TX-100) and cationic cetyltrimethylammonium bromide (CTAB) surfactants respectively. DFT calculation shows the possibility of formation of L.H(+) due to protonation at immine N and L.OH(-) due to introduction of OH(-) group at immine C. The relative stability of these two cationic and anionic species depends on the charge environment provided by surfactants. This influences the photoinduced electron transfer (PET) processes involved and results in different switch behaviour.