The Chidsey group research interest is to build the chemical base for molecular electronics. To accomplish this, we synthesize the molecular and nanoscopic systems, build the analytical tools and develop the theoretical understanding with which to study electron transfer between electrodes and among redox species through insulating molecular bridges. Members of the group have synthesized several series of saturated and conjugated oligomers with which we have studied the fundamental aspects of electron tunneling through well-defined molecular bridges. The oligophenylenevinylene bridge of these molecules promotes rapid tunneling over remarkably long distances compared with other unsaturated and saturated bridges we have studied. For instance, starting in the activated complex, the tunneling rate between a gold electrode and an appended ferrocene through 3.5nm of an oligophenylenevinylene (OPV) bridge is 8 x 109 s-1 whereas the tunneling rate through an alkane bridge of the same length is expected to be slower than 1s-1.
To date our electron-tunneling studies have largely focused on what we casually denote as a "one-electrode" measurement with the molecular bridge connecting one electrode to a redox species which acts as a molecular capacitor to an ionically conducting solution. The other electrodes necessary to measure the tunneling conduction are remotely located in an electrochemical cell. We are currently embarked on a broad based effort to make conduction measurements with two electrodes, one on each end of a single molecule. We are also developing strategies to include one or more additional electrodes so that molecular circuits with electrical power gain can be assembled. This effort is leading us to develop nanostructured wiring schemes and self-assembly methods for the construction of whole circuits of wired molecules. We will be examining nanowires formed from doped silicon and other substances. This emerging effort in nanowiring will be greatly aided by the previous work in the Chidsey lab on the surface chemistry of silicon, particularly the self-assembly of complex molecular monolayers on silicon surfaces.
1) "Selective Anodic Desorption for Assembly of Different Thiol Monolayers on the Individual Electrodes of an Array," J.P. Collman, A. Hosseini, T.A. Eberspacher, and C.E.D. Chidsey, Langmuir, 25, 6517 (2009).
2) "Growth of germanium crystals from electrodeposited gold in local crucibles," J.B. Ratchford, I.A. Goldthorpe, P.C. McIntyre, and C.E.D. Chidsey, Appl. Phys. Lett. , 94, 044103 (2009).
3) "Kinetic and mechanistic studies of the electrocatalytic reduction of O2 to H2O with mononuclear Cu complexes of substituted 1,10-phenanthrolines," C.C.L. McCrory, X. Ottenwaelder, T.D.P. Stack, and C.E.D. Chidsey, J. Phys. Chem. A 111, 12641-12650 (2007).
4) "Vertically Oriented Germanium Nanowires Grown from Gold Colloids on Silicon Substrates and Subsequent Gold Removal," J.H. Woodruff, J.B. Ratchford, I.A. Goldthorpe, P.C. McIntyre, and C.E.D. Chidsey, Nano Letters, 7, 1637-1642 (2007).
5) "Azide-Modified Graphitic Surfaces for Covalent Attachment of Alkyne-Terminated Molecules by "Click" Chemistry," A. Devadoss and C.E.D. Chidsey, J. Am. Chem. Soc. 129, 5370-5371 (2007).
6) "Rate of interfacial electron transfer through the 1,2,3-triazole linkage," N.K. Devaraj, R.A. Decreau, W. Ebina, J.P. Collman, and C.E.D. Chidsey, J. Phys. Chem. B, 110, 15955-15962 (2006).