Operating a Multi-Level Molecular Dimer Switch through Precise Tip-Molecule Control

TL;DR

This paper demonstrates a method to control multiple structural states of a molecular dimer on a surface using precise tip-molecule interactions, enabling on-demand switching for molecular electronics.

Contribution

It introduces a simple strategy to create and control multi-state molecular switches via tip manipulation and intermolecular interactions, advancing molecular device design.

Findings

Structural transitions can be induced and characterized at low temperature.

Intermolecular interactions enable new energy transfer pathways.

Precise tip control allows on-demand switching based on sample bias.

Abstract

Controlling structural transitions between molecular configurations is crucial for advancing functional molecular electronics. While reversible switching of bistable two-state molecules has been achieved, creating molecular systems that can be controllably switched between multiple configurations often requires complex synthetic methods, presenting a much greater challenge. In this study, we showcase a straightforward yet effective strategy to create and control transitions between multiple molecular structural states by forming a surface-bound molecular dimer. Using low-temperature scanning tunneling microscopy, we induce and characterize the structural transitions of a pyrrolidine dimer on a Cu(100) surface. The intermolecular interactions open new energy transfer channels, enabling the excitation through pathways that were inaccessible in monomers. The occupation of different molecular states is highly sensitive to both the energy of the tunneling electrons and the interaction with the STM tip. By precisely adjusting the tip-molecule distance, we can select the most probable structural configuration based on sample bias, thereby achieving on-demand control of this molecular dimer switch. This work highlights an approach that leverages both intermolecular and molecule-environment interactions to create and control an artificially fabricated molecular device.