C/.v-Platin

In this set of experiments you will synthesize both cis- and trans-platin complexes and study their substitution kinetics in DMSO. The primary focus of the chapter is on c/.v-platin biological reactivity you will investigate the binding of c/.v-platin to DNA adducts by NMR and molecular mechanics methods and assess drug cytotoxicity using a Chinese hamster ovary (CHO) cell line. 

Solvent intervention plays a major role in the biochemistry of platinum-based anticancer agents. The binding of c/.v-platin to DNA, for example, involves a sequential substitution of the Cl- ligands by solvent H20 followed by binding to the N7 of a guanine base, N7G. The rate determining step is Cl- substitution by solvent H20. For cis-platin, fcmo = 2.5 x 10-5 s-1 (t j2 = 7.7 h) and for fraws-platin, fcH20 = 9.8 x 10-5 s-1 (L/2= 1-96 h). 

Table 6. First Platination Rate Constants. Influence of the nature of the oligonucleotide on the platination with c V[PtY(NH3)2(H20)] (Y= H20, NH3, Cl) Scheme 4, Fig.) [99-103],...

Alguero, B. Lopez de la Osa, J. Gonzalez, C. Pedroso, E. Marchan, V. Grandas, A. Selective platination of modified oligonucleotides and duplex cross-links. Angew. Chem. Int. Ed. 2006, 45, 8194-8197. 

A platinum disk electrode was electrolytically platinized in a platinum chloride solution to increase the surface area and enhance the adsorption power. The platinized platinum electrode was then immersed in a solution containing 10 mg ml l ADH. 0.75 mM and 6.2 mM NAD. After sufficient adsorption of these molecules on the electrode surface, the electrode was transferred into a solution containing 0.1 M pyrrole and 1 M KC1. Electrochemical polymerization of pyrrole was conducted at +0.7 V vs. Ag/AgCl. The electrolysis was stopped at a total charge of 1 C cm 2. An enzyme-entrapped polypyrrole membrane was deposited on the electrode surface. 

An alcohol reduction method has been applied to the synthesis of polymer-stabilized bimetallic nanoparticles. They have been prepared by simultaneous reduction of the two corresponding metal ions with refluxing alcohol. For example, colloidal dispersions of Pd/Pt bimetallic nanoparticles can be prepared by refluxing the alcohol-water (1 1 v/v) mixed solution of palladium(II) chloride and hexachloro-platinic(IV) acid in the presence of poly(/V-vinyl-2-pyrrolidone) (PVP) at about 90-95°C for 1 h (Scheme 9.1.5) (25). The resulting brownish colloidal dispersions are stable and neither precipitate nor flocculate over a period of several years. Pd/ Pt bimetallic nanoparticles thus obtained have a so-called core/shell structure, which is proved by an EXAFS technique (described in Section 9.1.3.3). 

Thin-film dielectrics (Ba0 92Ca108)(Ti0 92Zr0 08)O3 for the thin-film capacitors were prepared using Ba, Ca, and Zr ethoxides and Ti isopropoxide in refluxed methoxyethanol solutions as precursors. Films were deposited on a usual platinized Si substrate. Crystalline thin films after heat treatment at 800°C demonstrated dielectric permittivity of 1200, dielectric loss of0.5%, nonlinear coefficient a = 0.92, and break-down voltage of980 V [1595],... 

Allis-Chalmers hat eine 40zelhge Methanol-Sauerstoff-Batterie mit 500 W Leistung gebaut 19). Bei der Arbeitstemperatur von 50°C betragt die Stromdichte 60 mA/cm bei 0,4 V Spannung. Die Anoden bestehen aus Nickel und haben einen Platin-Palladium-Katalysator. 

Eine Reihe von Methanol-Batterien ist vom Institut Fran ais du Pdtrole, Paris, entwickelt worden. Sie haben Kohleelektroden die Anode ist mit Platin ausgenistet. Die Firma Varta, Frankfurt/Main, verwendet ebenfalls Platinschwarz als Katalysator fiir die Methanol-Elek-trode. Sie fiihrte 1965 eine Batterie mit 50 W Leistung vor (27). Bei einer Temperatur von 60 °C betrdgt die Stromdichte 10 vaA/cm und die Zellspanmmg 0,5 V. 

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