Alexis L. Thompson, K. R. Justin Thomas, Todd J. Martinez, Christopher J. Bardeen, and Sankaran Thayumanavan
Donor-bridge-acceptor complexes consisting of a carbazole electron donor and naphthalimide acceptor linked by either para- or meta-substituted phenylacetylene bridges (Para and Meta) are synthesized. Their charge transfer properties are studied using time-resolved and steady state spectroscopy and semiempirical electronic structure theory. The analysis shows that the forward electron transfer, modulated by the excited state electronic coupling matrix element VDA*, is rapid in both molecules, but that charge recombination, which depends on the ground state VDA, is ten times slower in Meta. This discrepancy is attributed to different VDA*/VDA ratios in the different bridge structures, similar to the enhanced excited state excitonic coupling observed previously in meta-linked phenylacetylene dendrons.