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Full-Text Articles in Physical Sciences and Mathematics

Three-Terminal Devices To Examine Single Molecule Conductance Switching, Z K. Keane, Jacob W. Ciszek, J M. Tour, D Natelson Jul 2006

Three-Terminal Devices To Examine Single Molecule Conductance Switching, Z K. Keane, Jacob W. Ciszek, J M. Tour, D Natelson

Chemistry: Faculty Publications and Other Works

We report electronic transport measurements of single-molecule transistor devices incorporating bipyridyl-dinitro oligophenylene-ethynylene dithiol (BPDN-DT), a molecule known to exhibit conductance switching in other measurement configurations. We observe hysteretic conductance switching in 8% of devices with measurable currents, and find that dependence of the switching properties on gate voltage is rare when compared to other single-molecule transistor devices. This suggests that polaron formation is unlikely to be responsible for switching in these devices. We discuss this and alternative switching mechanisms.


Single-Molecule Transistors: Electron Transfer In The Solid State, Douglas Natelson, Lam H. Yu, Jacob W. Ciszek, Zachary K. Keane, James M. Tour May 2006

Single-Molecule Transistors: Electron Transfer In The Solid State, Douglas Natelson, Lam H. Yu, Jacob W. Ciszek, Zachary K. Keane, James M. Tour

Chemistry: Faculty Publications and Other Works

Single-molecule transistors (SMTs) incorporating individual small molecules are unique tools for examining the fundamental physics and chemistry of electronic transport in molecular systems at the single nanometer scale. We describe the fabrication and characterization of such devices, and the synthesis and surface attachment chemistry of novel transition metal complexes that have been incorporated into such SMTs. We present gate-modulated inelastic electron tunneling vibrational spectroscopy of single molecules, strong Kondo physics (TK ∼ 75 K) as evidence of excellent molecule/electrode electronic coupling, and a demonstration that covalent attachment chemistry can produce SMTs that survive repeated thermal cycling to room …


Pyrrolizidine Esters And Amides As 5-Ht4 Receptor Agonists And Antagonists, Daniel Becker, Daniel L. Flynn, Alan E. Moormann, Roger Nosal Feb 2006

Pyrrolizidine Esters And Amides As 5-Ht4 Receptor Agonists And Antagonists, Daniel Becker, Daniel L. Flynn, Alan E. Moormann, Roger Nosal

Chemistry: Faculty Publications and Other Works

A series of pyrrolizidine esters, amides, and ureas was prepared and tested for 5-HT(4) and 5-HT(3) receptor binding, 5-HT(4) receptor agonism in the rat tunica muscularis mucosae (TMM) assay, and for 5-HT(3) receptor-mediated functional antagonism in the Bezold-Jarisch reflex assay. Several pyrrolizidine derivatives were identified with high affinity for the 5-HT(4) receptor, including benzamide 12a (SC-53116), a potent and selective 5-HT(4) partial agonist that exhibits efficacy in promoting antral contractions and activity in promoting gastric emptying in canine models. Also discovered were 5-HT(4) receptor antagonists, including imidazopyridine amide 12h (SC-53606), which is a potent and selective 5-HT(4) receptor antagonist with …


Controlling Charge Injection In Organic Field-Effect Transistors Using Self-Assembled Monolayers, B H. Hamadani, D A. Corley, Jacob W. Ciszek, J M. Tour, D Natelson Jan 2006

Controlling Charge Injection In Organic Field-Effect Transistors Using Self-Assembled Monolayers, B H. Hamadani, D A. Corley, Jacob W. Ciszek, J M. Tour, D Natelson

Chemistry: Faculty Publications and Other Works

We have studied charge injection across the metal/organic semiconductor interface in bottom-contact poly(3-hexylthiophene) (P3HT) field-effect transistors, with Au source and drain electrodes modified by self-assembled monolayers (SAMs) prior to active polymer deposition. By using the SAM to engineer the effective Au work function, we markedly affect the charge injection process. We systematically examine the contact resistivity and intrinsic channel mobility and show that chemically increasing the injecting electrode work function significantly improves hole injection relative to untreated Au electrodes.