A single fluorophore to address multiple logic gates

Abstract

Logic gates with different radixes have been constructed using a biologically active molecule, 2-(4′-N,N-dimethylaminophenyl)imidazo[4,5-b]pyridine (DMAPIP-b). Taking advantage of the multiple binding sites of the fluorophore, a series of different molecular logic gates are developed using fluorescence intensities at different wavelengths. The high emission of the molecule is drastically quenched in the presence of Fe³⁺. It is regained by the addition of an equivalent amount of F⁻. The fluorescence On–Off nature has been used to construct molecular full subtractor and molecular keypad lock system with Boolean logic. A ternary system is generated by considering three defined fluorescence intensities at particular wavelengths. The smooth dependency of emission intensities with analyte concentration is utilized to construct an infinite-valued fuzzy logic system. The fuzzy logic system is further coupled with a neuro-adaptation method to predict more accurately the dependency of molecular intensity on external inputs.