Highly Selective and Sensitive (PPB Level) Quinolin‐Based Colorimetric Chemosensor for Cu(II)

Abstract

Abstract4‐(quinolin‐2‐ylmethylene)aminophenol (QMAP) is synthesised in a one‐step synthetic process and was checked for its sensing ability towards metal ions. The molecule is found to be effective for the instantaneous selective and sensitive Cu(II) ion detection in PPB level in methanolic solution with a distinct development of orangish yellow colour from a colourless solution, which can be detected visually. The sensing ability of the QMAP towards Cu(II) is found independent on the type of counter anions and also in the presence of other metal ions. QMAP does not show any colour change in the presence of other metal salts. A 2 : 1 binding stoichiometry between QMAP and Cu(II) with a large binding constant of 3.2 x 1010 M−2 has been measured. Quantum chemical calculations have been used to understand the nature of the complex and the mechanism of the sensing.