ELECTRON-TRANSFER KINETICS OF CONTACTING MONOLAYERS

The rates of electron-transfer reactions between the monolayers of metal complexes in contact at polymer/polymer interfaces have been evaluated for the thermodynamically disfavored cross-reactions poly[Os(bpy)2(vpy)Cl]2+ + poly[Os-(bpy)2(vpy)2]2+, poly[Os(bpy)2(vpy)2]3+ + poly[Ru(vbpy)3]2+, and poly[Os(bpy)2(vpy)2]3+ + poly[Ru(bpy)2(vpy)2]2+. An analysis of the interfacial electron-transfer rates that accounts for the thermodynamically favored back-reaction gives rate constants 2.8 ⨯ 103, 1.1 ⨯ 103, and 2 ⨯ 102 M-1 s-1, respectively, that agree with values estimated from classical electron-transfer theory: 3.1 ⨯ 103, 1.1 ⨯ 103, and 1.5 ⨯ 102 M-1 s-1. The second of these three reactions was studied with the two polymer films both in contact and separated by a metal junction, with no discernable difference in the results. The metal-separated experiment allowed examination of the polymer/polymer junction's interfacial potential, which is interpreted as a mixed potential. © 1990, American Chemical Society. All rights reserved.