A Single-Molecule Junction Based on a Covalent Organic Cage

Abstract

As the applications of molecular cages hinge on their properties, understanding the true nature of the cage structures is imperative. Single-molecule conductance technique offered a unique opportunity to explore the property of an individual cage structure, yet the undefined cage-electrode connection remains challenging. Herein, we designed a new single-molecule junction based on covalent organic cages with sulfur atoms on the edges as defined anchor groups. Using scanning tunneling microscopy break junction method, the single-molecule conductance was found at 10^-3.5 G₀, indicating the formation of a stable junction by the cage. The investigation, combining control structures and theoretical studies, confirmed that the conductance signal originates from the connection between gold electrodes and sulfur atoms in adjacent benzothiadiazole groups. This well-defined connection allowed us to analyze electron transport within the cage structure, providing new insights into the property investigation of functional cages.

Keywords: Benzothiadiazole; Covalent organic cages; Defined connection; Molecular cage junction; Single‐molecule conductance.