Chemical-Driven Reconfigurable Arithmetic Functionalities within a Fluorescent Tetrathiafulvalene Derivative

The charge transfer phenomena within a tetrathiafulvalene-derived fluorescent switch, 2-[4-(2,2′-bi-1,3-dithiol-4-yl)-5-methoxy-1,3-thiazol-2-yl]-2-pyridine (2-MT) is investigated via various spectral and theoretical approaches at both the ground state and the excited state. At different oxidation states of 2-MT, the charge transfer behaviors between the redox switch, tetrathiafulvalene (TTF), and the fluorophore, 5-methoxy-2-(2-pyridyl)thiazole (2-MPT), can be tuned differently. When a set of chemical inputs are introduced, the redox reactions coupled with coordination and protonation reactions trigger distinct charge-transfer processes within the ground state and the excited state, which are evidenced in both the absorption and fluorescent spectrum. The chemical-driven spectral changes thus provide parallel output channels to construct reconfigurable molecule-based binary algebra functionalities, that is, the half adder and the half subtractor. The charge-transfer induced fluorescence recovery of 2-MT is also sensitive to the input sequence, which implements a molecular keypad lock within the TTF derivative for the first time.