Two and three input molecular logic operations mediated by a novel azo-azomethine based chromogenic probe through intramolecular charge transfer processes

Abstract

A novel azo-azomethine based chromogenic receptor containing a diaminomaleonitrile fragment and a pyridine ring has been designed and synthesized for the fabrication of multifunctional molecular logic circuits. The current system exhibited absorption response profiles varying significantly with different anionic and cationic inputs in DMSO–water (9 : 1) through the modulation of intramolecular charge transfer (ICT) processes. The responsive mechanism of the system was also explored and elucidated. Importantly, the changes in absorbance output signals at particular wavelengths in response to F⁻ and Zn²⁺ as two chemical inputs provided opportunities for the elaboration of 2-bit Boolean binary logic functions like OR and INHIBIT gates. Successfully, a 3-input logic network composed of an EnNOR combinational circuit could also be interpreted using F⁻, Zn²⁺ and Cu²⁺ as input variables. Furthermore, the integration of fundamental logic functions was discussed to establish complex logic circuits including reconfigurable 2-bit logic gates and the three-input combinatorial logic circuits. More interestingly, based on the reversible and reproducible switching behaviour of the fluoride interaction with Ca²⁺, we presented a potential “Write–Read–Erase–Read” memory function possessing multi-write ability.