Selective detection of Cu²⁺ by benzothiazole-based colorimetric chemosensor: a DFT study

An effectively selective colorimetric chemosensor BTV (2-methoxy-6-((E)-(((E)-3-methylbenzo[d]thiazol-2(3H)-ylidene)hydrazono)methyl)phenol) was synthesized for detecting Cu²⁺. The BTV having benzothiazole group showed a bathochromic shift (150 nm) with an explicit color variation from colorless to pink toward Cu²⁺. The BTV could detect Cu²⁺ down to 0.37 μM in solution. The binding ratio of BTV and Cu²⁺ was determined to be a 1:2 by Job plot and ESI-MS. Sensor BTV could distinctly sense Cu²⁺ without interference from other cations and distinguish it from diverse metal ions through the test strip. The sensing process of Cu²⁺ by BTV was presented by UV-visible titration, Job plot, ¹H NMR titration, DFT calculation, FT-IR and ESI-MS. Graphical abstract: An effective colorimetric chemosensor BTV was synthesized for detecting Cu²⁺. Sensor BTV showed a bathochromic shift (150 nm) with an explicit color change from colorless to pink to Cu²⁺. In addition, it could detect Cu²⁺ down to 0.37 μM and distinguish it from various metal ions through the test strip. [Figure not available: see fulltext.]