Dihydrazone Schiff base ligands – appropriate chemosensors for Cd(II) detection

The investigation of dihydrazone Schiff base ligands as potential and appropriate chemosensors for fast, simple and portable detection of Cd(II) ion is reported. [Display omitted] •Dihydrazone Schiff bases – chemosensors for Cd(II) ion.•Photoluminescence on/off effect upon coordination of Schiff bases with Cd(II).•Fluorescence of ligands is enhanced when Cd(II) is added to test paper strips. Finding suitable probes for the rapid and sensitive detection of highly toxic pollutants is an urgent challenge for our environment. In this paper, three Schiff base ligands (H2L1 = 2,6-diacetylpyridine bis(isonicotinoylhydrazone), H2L2 = 2,6-diacetylpyridine bis(nicotinoylhydrazone) and H2L3 = 2,6-diacetylpyridine bis(picolinoylhydrazone)) have been used as potential chemosensors for Cd2+ detection. The corresponding Cd(II) complexes were prepared and it was found that the chemosensors coordinate similarly to the Cd2+ ion, eventually exhibiting different photoluminescent responses. Coordination of H2L1 and H2L2 to the Cd(II) ion results in a “turn-off” photoluminescence, while coordination of H2L3 show an excellent example of a “turn-on” mode of photoluminescence. Moreover, all three studied ligands are appropriate candidates for a fast, simple and portable method of Cd(II) ion detection.