A thiacalix[4]crown based chemosensor for Zn²⁺ and H₂PO₄⁻: sequential logic operations at the molecular level

Abstract

A thiacalix[4]crown based di-topic receptor 3 possessing two types of binding sites viz. crown-5 ring and imino moieties has been synthesized which undergoes fluorescence enhancement in the presence of Zn(2+) ions. The selective binding of Zn(2+) to compound 3 does not allow the K(+) ions to bind with the crown-5 ring and thus a negative allosteric behaviour has been observed between Zn(2+)/K(+) ions. In addition, the 3-Zn(2+) complex can be used for the detection of H2PO4(-) ions with a fluorescence "turn-off" response. Furthermore, based on the fluorescence response, a two input and one output sequential logic circuit has been constructed.