Cycloaddition Functionalizations to Preserve or Control the Conductance of Carbon Nanotubes

TL;DR

This paper explores covalent cycloaddition functionalizations that can preserve or modulate the electrical conductance of single-walled metallic carbon nanotubes, enabling reversible conductance switching through chemical, optical, or thermal control.

Contribution

It introduces a class of cycloaddition reactions that can recover pristine conductance or switch conductance states in carbon nanotubes, depending on bond cleaving and reformation.

Findings

Cycloaddition can induce bond cleaving, restoring ideal conductance.

Certain nanotube diameters exhibit bistable states for conductance switching.

Conductance can be controlled chemically, optically, or thermally.

Abstract

We identify a class of covalent functionalizations that preserves or controls the conductance of single-walled metallic carbon nanotubes. [2+1] cycloadditions can induce bond cleaving between adjacent sidewall carbons, recovering in the process the $sp^2$ hybridization and the ideal conductance of the pristine tubes. This is radically at variance with the damage permanently induced by other common ligands, where a single covalent bond is formed with a sidewall carbon. Chirality, curvature, and chemistry determine bond cleaving, and in turn the electrical transport properties of a functionalized tube. A well-defined range of diameters can be found for which certain addends exhibit a bistable state, where the opening or closing of the sidewall bond, accompanied by a switch in the conductance, could be directed with chemical, optical or thermal means.