Non‐Exponential Distance Dependence of Bridge‐Mediated Electronic Coupling

Donor chromophores attached to oligo(phenyleneethynylene) molecular bridges of varying length have attenuation factors for electron tunneling β that vary systematically with the donor–bridge (DB) energy gap (see picture). Investigations show that for bridges with ethynylene and vinylene repeating subunits, the electronic coupling increases with increasing donor–acceptor (DA) distance. A simple model accounts for this unexpected observation.