Interplay between Barrier Width and Height in Electron Tunneling: Photoinduced Electron Transfer in Porphyrin-Based Donor-Bridge-Acceptor Systems
Artikel i vetenskaplig tidskrift, 2006

The rate of electron tunneling in mol. donor-bridge-acceptor (D-B-A) systems is detd. both by the tunneling barrier width and height, i.e., both by the distance between the donor and acceptor as well as by the energy gap between the donor and bridge moieties. These factors are therefore important to control when designing functional electron transfer systems, such as constructs for photovoltaics, artificial photosynthesis, and mol. scale electronics. The authors have studied a set of D-B-A systems in which the distance and the energy difference between the donor and bridge states (DEDB) are systematically varied. Zinc(II) and gold(III) porphyrins were chosen as electron donor and acceptor because of their suitable driving force for photoinduced electron transfer (-0.9 eV in butyronitrile) and well-characterized photophysics. The authors have previously shown, in accordance with the superexchange mechanism for electron transfer, that the electron transfer rate is proportional to the inverse of DEDB in zinc/gold porphyrin D-B-A systems with bridges of const. edge to edge distance (19.6 .ANG.) and varying DEDB (3900-17,600 cm-1). Here, the authors use the same donor and acceptor but the bridge is shortened or extended giving a set of oligo-p-phenyleneethynylene bridges (OPE) with four different edge to edge distances ranging from 12.7 to 33.4 .ANG.. These two sets of D-B-A systems-ZnP-RB-AuP+ and ZnP-nB-AuP+-have one bridge in common, and hence, for the first time both the distance and DEDB dependence of electron transfer can be studied simultaneously in a systematic way. [on SciFinder (R)]

interplay barrier width height electron tunneling

photoinduced intramol electron transfer porphyrin donor bridge acceptor

Författare

Karin Pettersson

Chalmers, Kemi- och bioteknik, Fysikalisk kemi

Joanna Wiberg

Chalmers, Kemi- och bioteknik, Fysikalisk kemi

Thomas Ljungdahl

Chalmers, Kemi- och bioteknik, Fysikalisk kemi

Jerker Mårtensson

Chalmers, Kemi- och bioteknik, Organisk kemi

Bo Albinsson

Chalmers, Kemi- och bioteknik, Fysikalisk kemi

Journal of Physical Chemistry A

1089-5639 (ISSN) 1520-5215 (eISSN)

Vol. 110 319-326

Ämneskategorier

Fysikalisk kemi

DOI

10.1021/jp054420s