Electron-transport properties of ethyne-bridged diphenyl zinc-porphyrin molecules

TL;DR

This study uses first-principles calculations to analyze how molecular conformation affects electron transport in ethyne-bridged diphenyl zinc-porphyrin molecules, revealing significant conductance differences based on ring orientation.

Contribution

It demonstrates the impact of molecular geometry on conductance, highlighting the role of π and σ states in electron transmission in these molecules.

Findings

Perpendicular configuration reduces conductance by three orders of magnitude.

Coplanar configuration allows electron transmission through π states.

Electron hopping between π and σ states is key to conductance variation.

Abstract

We investigate the electron-transport properties of ethyne-bridged diphenyl zinc-porphyrin molecules suspended between gold (111) electrodes by first-principles calculations within the framework of density functional theory. It is found that the conductance of a molecular junction in which phenyl and porphyrin rings are perpendicular is reduced by three orders of magnitude compared with that of a junction in which the phenyl and porphyrin rings are coplanar. In the coplanar configuration, electrons are transmitted through $\pi$ states, which extend over the whole molecule. In the perpendicular configuration, the conductance is suppressed because of the reduction of electron hopping between $\pi$ states of the phenyl ring and $\sigma$ states of the porphyrin ring.