Functionalized oligo(phenyleneethynylene)s (OPEs) show potential
as molecular wires for molecular electronics. A selection of OPEs
with vertically disposed extended tetrathiafulvalene (TTF) units
has been synthesized by a combination of metal-catalyzed cross-coupling
and Wittig reactions. Two general synthetic routes were developed.
In one route, the OPE scaffold was first constructed and finally
the extended TTF units were incorporated by Wittig reactions. In
the second route, the extended TTF module was first prepared and
subsequently incorporated into an OPE backbone by palladium-catalyzed
cross-coupling reactions. The latter route was employed for functionalization
with protected thiol end-groups. Owing to the shape of these redox-active
molecules, they are termed ‘OPE-TTF cruciforms’.
The electronic properties were investigated by UV-Vis spectroscopy
and by cyclic voltammetry.
alkynes - conjugation - cross-coupling - sulfur - Wittig reaction
