Benzothiazole appended lower rim 1,3-di-amido-derivative of calix[4]arene: Synthesis, structure, receptor properties towards Cu~(2+), iodide recognition and computational modeling

摘要

A new molecular fluorescent sensor (L) for Cu~(2+) has been synthesized by derivatizing the lower rim of calix[4]arene with benzothiazole moiety, through amide linkage to result in 1,3-di-derivative. The receptor molecule, L exhibited fluorescence quenching towards Cu~(2+) among eleven divalent ions, viz., Mn~(2+), Fe~(2+), Co~(2+), Ni~(2+), Cu~(2+), Zn~(2+), Cd~(2+), Hg ~(2+), Ca~(2+), Mg~(2+) and Pb~(2+), studied. The 1:1 stoichiometry of the complex formed between L and Cu~(2+) has been demonstrated by electronic absorption and ESI-MS. The role of calix[4]arene for the selective sensing of Cu~(2+) has been established by comparing the data with that obtained for an appropriate control molecule. The minimum concentration at which L can detect Cu~(2+) has been found to be 403 ppb. The computations carried out at DFT level have provided the coordination and structural features of the Cu~(2+) complex of L as species of recognition. The Cu~(2+) complex thus formed recognizes iodide by bringing change in the color, among the 14 anions studied.