Long range electron transfer across $\pi$-conjugated systems: role of electron correlations

TL;DR

This paper investigates long-range electron transfer in polyene chains, revealing that strong electron-electron interactions enable transfer over distances much larger than predicted by standard theories.

Contribution

It demonstrates that electron correlations significantly enhance long-range electron transfer, challenging traditional models like Forster theory.

Findings

High electron transfer rates observed at 45 Å distance

Electron-electron interactions cause electron deconfinement

Accurate calculations confirm the role of correlations

Abstract

We consider a prototype polyene chain: donor-$\pi$(bridge)-acceptor. The distance between the donor and the acceptor is varied by increasing the number of bridged atoms and rate of electron transfer, k$_{et}$ is studied for a series of different donors, D=NH$_2$, SH, OH, and a fixed acceptor, A=NO$_2$. We observe a large k$_{et}$ even at a very large D-A separation of $\sim$ 45 $\AA$, unexpected from the well-known and standard theories like the Forster theory. Such a long range electron transfer is due to the strong electron-electron interactions in the bridged orbitals that result in deconfinment of electrons in donor orbitals. Calculations at various levels: semi-empirical and many-body exact, have been performed to accurately account for such correlations.