Oxazine: an anchoring group serving as functional kernels to construct single-molecule switches

Abstract

As a central research target in molecular electronics, molecular switches have been extensively explored over the past decades. We theoretically demonstrate that when linking appropriate conjugated molecules to carbon electrodes, the de/rehydrogenation of 1,4-oxazine linkers efficiently switches single-molecule junctions between a low-conducting and a high-conducting state. This change is attributed to the modified energy gap of the central molecule as well as the charge rearrangement at the molecule–electrode interfaces. Based on the above findings, a single-molecule junction, employing an intramolecular proton transfer reaction as the switching mechanism, has been proposed. This realizes a maximum ON/OFF current ratio as high as 1.5 × 10³. Furthermore, we show that an electrostatic gate field can control the proton transfer process and thus allow specific conductance states to be selected. Our findings provide a new perspective for the design of single-molecule switches relying on the anchoring groups rather than on the specific molecular backbones.