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.

A rhodamine embedded bio-compatible smart molecule mimicking a combinatorial logic circuit and ‘key-pad lock’ memory device for defending against information risk

“…Based on various spectroscopic observations like the chromofluorogenic dual signalling response of Al 3+ and the colorimetric through controlled experiments some interesting chemistry related to mimicking advanced logic operations and various output information is noted, which could be interpreted within the framework of various molecular logic circuits. 41 In order to correlate various arithmetic logic operations, we arbitrarily choose threshold values of 0.20 for absorbance and 2 Â 10 6 for fluorescence intensity. Any spectral values of outputs lower than the respective threshold limits are taken as 0 (OFF-state) while those greater than the threshold limit are taken as 1 (ON-state).…”