Platinum molecular wire

Electron transfer of the glucose oxidase/polypyrrole on the electrode surface was confirmed by differential pulse voltammetiy and cyclic voltammetry. The glucose oxidase clearly exhibited both reductive and oxidative current peaks in the absence of dissolved oxygen in these voltammograms. These results indicate that electron transfer takes place from the electrode to the oxidized form of glucose oxidase and the reduced form is oxidized by electron transfer to the electrode through polypyrrole. It may be concluded that polypyrrole works as a molecular wire between the adsorbed glucose oxidase and the platinum electrode. 

Figure 11.30 An insulated molecular wire based on a platinum(II) polyalkyne surrounded by two long-chain diphosphines. The polyalkyne wire (shown dark in the middle of the structure) is barely visible within the insulation.45...

RNA, and proteins when compressed between platinum electrodes. Subsequent studies have established that proteins and ss DNA or RNA do not function as molecular wires however, the conductivity of ds DNA remains the subject of debate. Recently there have been several studies of DNA conductivity in fibers, single crystals, aligned films, and monolayer assemblies. Far from resolving the controversy, they seem to have intensified it. 

Scheme 10.21. Molecular wire-like platinum(ii) terpyridyl complexes of different lengths.

Adsorption experiments were conducted on chromium, platinum, cadmium, and zinc the sources and preparation of these metal specimens have been reported previously (16). In preparing adsorbed, mono-molecular layers by adsorption directly from the molten pure acid (5), the clean adsorbing substrate was first heated to a temperature just above the melting point of the acid (see Table I), a few crystals of the acid were sprinkled on the surface, and the resulting pool of molten acid was teased over the whole surface with a previously freshly flamed platinum wire. If spontaneous retraction of the liquid acid did not occur, the specimen was allowed to cool and all of the solidified material adhering on top of the adsorbed monolayer was removed by appropriate solvent treatments as discussed below. 

C. Femoni, F. Kaswalder, M. C. Iapalucci, G. Longoni, and S. Zacchini, Infinite Molecular [Pt3n(CO)6n]2 Joo Conductor Wires by Self-Assembly of [Pt3n(CO)gn]2 (n = 5-8) Cluster Dianions Formally Resembling CO-Sheathed Three-Platinum Cables, Eur. J. Inorg. Chem. 2007, 1483-1486. 

Polycrystalline Platinum.—Three desorption peaks are observed with Pt powders (170, 250, and 360 K) and films (120, 200, 330 K) [compare Pt(lll)]. Calculated heats of desorption for Pt films are 34, 50, and 88 kJ moP Similar values are found with Pt wire (71 kJ moP at 0 = 0.37 decreasing to 46 kJ moP at 0 = 0.46). Surface potential measurements on Pt films are consistent with work function data for single crystals. In both cases the most strongly bound H, located at surface imperfections, has a partial negative charge, while H on terrace sites has a partial positive charge. Dus and Tompkins also report a weakly bound (5 kJ moP ) molecular species, H2, which only adsorbs at high pressures. 

Sulfur hexafluoride. The hexafluoride is normally very resistant to attack and extreme conditions are often required. Thus SF6 resists molten KOH and steam at 500°. It reacts with 02 when a platinum wire is exploded electrically,34 also with some red-hot metals and with alkali metals in liquid ammonia.35 Because of its inertness, high dielectric strength and molecular weight, it is used as a gaseous insulator in high-voltage generators and other electrical equipment.---------------------------------------------------------... 

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