Synthesis and photophysical investigation of (BTHN) Schiff base as off-on Cd2+ fluorescent chemosensor and its live cell imaging

A Schiff base, 1-[2-(1,3-benzothiazol-2-yl)hydrazinylidene]methyl-naphthalen-2-ol (BTHN) have been synthesized by the condensation of 2-hydrazinobenzothiazole and 2-hydroxy-1-naphthaldehyde. Structure of BTHN has been determined with the help of spectroscopic techniques and elemental analysis. Photophysical parameters of the BTHN were studied in the different solvents of varying polarity. The photophysical parameter were largely affected by the varying polarity and absorption as well as emission spectra showed strong bathochromic shift. Further, interactions of the BTHN dye with metal ions were also explored by spectrofluorimetry and BTHN found to be an excellent off-on chemosensor for Cd2+ in DMF-H2O solution. The molecular coordination complex between BTHN with Cd2+ is 1:1, confirmed by Benesi-Hildebrand and Job-plot method. In addition, the BTHN has been effectively employed for the fluorescence imaging of cadmium ions in the living cells.