A Molecular Full-Adder and Full-Subtractor, an Additional Step toward a Moleculator

TLDR

Over the past decade, progress in molecular logic and arithmetic systems has brought chemists closer to realizing a molecular‑scale calculator (a Moleculator). This paper reports a significant step toward that goal. The authors modify the processor’s initial state and introduce degeneracy or controlled interactions among chemical inputs to simplify the implementation of three‑bit addition and subtraction. By integrating new and existing molecular logic reconfiguration methods, the authors loaded advanced arithmetic onto a single fluorescein molecule, and using multi‑wavelength monitoring and negative logic transmittance, they achieved the first molecular full‑adder and full‑subtractor with a simple UV‑vis setup.

Abstract

Over the past decade, there has been remarkable progress in the development of molecular logic and arithmetic systems, which has brought chemists closer to the realization of a molecular scale calculator (a Moleculator). This paper describes a significant step in this direction. By integrating past and new approaches for molecular logic reconfiguration, we were able to load advanced arithmetic calculations onto a single molecular species. Exchanging chemical inputs, monitoring at several wavelengths simultaneously, as well as using negative logic for the transmittance mode significantly increase the input and output information channels of the processing molecule. Changing the initial state of the processor is an additional approach used for altering the logical output of the device. Finally, introducing degeneracy to the chemical inputs or, alternatively, controlling their interactions to form identical chemical states minimizes the complexity of realizing three-bits addition and subtraction at the molecular scale. Consequently, using a commercially available fluorescein molecule, acid and base chemical inputs, and a simple UV−vis measurement setup, integration of a full-adder and, for the first time, a full-subtractor is now possible within individual molecules.