A New Cr3+ Electrochemical Sensor Based on ATNA/Nafion/Glassy Carbon Electrode

A new electrochemical sensor of metal cation in an aqueous solution based on homobifunctional tridentate disulfide Schiff base and named 1,1'-(-((disulfanediylbis(2,1-phenylene))bis(azaneylylidene))bis(methaneylylidene))bis(naphthalene-2-ol) (ATNA) was easily obtained quantitatively from the condensation reaction of 2-hydroxy-1-naphthaldehyde and<i>2-</i>aminothiophenol, and then fully characterized by spectroscopic techniques for structure elucidation. The molecular structure of ATNA was also confirmed by a single-crystal X-ray diffraction study to reveal a new conformation in which the molecule was stabilized by the O-H…N type intramolecular hydrogen bonding interactions in both moieties. The ATNA was used as a selective electrochemical sensor for the detection of chromium ion (Cr³⁺). A thin film of ATNA was coated on to the flat surface of glassy carbon electrode (GCE) followed by 5 % ethanolic Nafion in order to make the modified GCE (ATNA/Nafion/GCE) as an efficient and sensitive electrochemical sensor. It was found to be very effective and selective against Cr³⁺ cations in the company of other intrusive heavy metal cations such as Al³⁺, Ce³⁺, Co²⁺, Cu²⁺, Ga³⁺, Hg²⁺, Mn²⁺, Pb²⁺, and Y³⁺. The detection limit at 3 S/N was found to be 0.013 nM for Cr³⁺ ions within the linear dynamic range (LDR) (0.1 nM-10.0 mM) of Cr³⁺ ions with r² = 0.9579. Moreover; this work instigates a new methodology for developing the sensitive as well as selective electrochemical toxic cationic sensors in the field of environmental and health care.