Long-range electron transfer across a π-conjugated chain: role of electron correlations

Abstract

We consider a prototype polyene chain donor-Π(bridge)-acceptor. The distance between the donor and the acceptor is varied by increasing the number of atoms in the bridge and the rate of electron transfer k_ET is studied for a series of different donors D=NH₂, OCH₃, SCH₃, and a fixed acceptor A=NO₂. We observe a large k_ET even at a D-A separation of ~45 Å, unexpected from the standard noninteracting theories. Such a long-range electron transfer is primarily due to the formation of bound electron-hole pair (exciton) across the donor-bridge-acceptor atoms. Calculations at various levels, semi-empirical (with inclusion of configuration interactions) and many-body models (using density matrix renormalization group theory), have been performed to accurately account for such electron correlations.