Electrochemistry and blocking properties of thin films of platinum phenylethynyl complexes

We report the electrochemical characterization of thin films of trans-bis(tri-n-butylphosphine)bis(phenylethynyl)platinum(II) and related compounds. Thin films of these materials are interesting because they have exhibited nonlinear optical behavior. Films were deposited on platinum and glassy carbon electrodes by either dropcasting a solution of the platinum complex onto an electrode surface and allowing it to dry, or soaking the electrode in the solution for 30 min. Cyclic voltammetry of the films indicates an irreversible oxidation, as seen in solution. These waves are surface-confined for some species but not all of them. Surface coverages indicate that films exceed the thickness of a single monolayer. Cyclic voltammetry of ferrocene through the films shows a reduction in peak current and an increase in peak separation. The films made of more nonpolar probes block ferrocene to a greater degree than more polar ones.