First step in chemical preparation of metal nanogaps bridged by thiol end-capped molecular wires.

We present a strategy for chemical preparation of multiple copies of single-molecule electronic devices that is based on chemical self-assembly under equilibrium conditions in aqueous solution. As a first step in the realization of this, we show that thiol end-capped oligo(phenylenevinylene)s (OPVs) can be rendered water-soluble by forming well-defined stoichiometric supramolecular complexes with α-cyclodextrins. On the basis of fluorescence intensity measurements in water, a 1:3 stoichiometry was determined for the complexes with equilibrium constants of the order of 5 × 10(-2) M(-2). The photophysical properties of the OPV3s as free molecules in solution, as nanoaggregates in aqueous suspension, and embedded in cyclodextrins in water, are reported, and the prospects of using these complexes as nucleation sites for growth of gold nanorods bridged by electronically active thiol end-capped molecules is discussed.