Electronic Coupling of Molecular Complexes to Au Electrodes Mediated via Host–Guest Interactions

TL;DR

This paper explores how molecular complexes can be electronically coupled to gold electrodes using host-guest interactions, enabling long-range coupling despite a large distance.

Contribution

The study demonstrates long-range electronic coupling mediated by host-guest interactions, which is novel for molecular complexes on gold electrodes.

Findings

Host-bound guests show substantial electronic coupling to the Au surface despite being ∼1.3 nm away.

Surface-enhanced infrared absorption spectroscopy confirms distinct spectral features of host-bound species.

Density functional theory calculations highlight the host's role in mediating long-range coupling.

Abstract

Immobilization of
molecular catalysts onto electrode surfaces using
host–guest (HG) interactions enables the facile regeneration
of electrodes following catalyst degradation. Beyond this practical
aspect, the architecture also offers a unique way to study the electronic
coupling of molecules to the electrode through a nominally insulating
linker. Here, we employ surface-enhanced infrared absorption spectroscopy
(SEIRAS) to characterize the binding and electronic coupling of Au-bound
HG complexes. Distinct spectral features and binding kinetics differentiate
host-bound species from physisorbed analogues, confirming well-defined
HG assemblies on the surface. Analysis of the wavenumber shifts of
the guest as a function of applied potential suggests that while the
coupling of physisorbed guests with the surface is not strong, the
host-bound guests show a substantial electronic coupling considering
their distance from the surface of ∼1.3 nm. Density functional
theory calculations reveal the key role of the host in mediating this
long-range coupling between the Au surface and the guest.

Figures