Synthese von Porphyrin- und Chlorinderivaten zur Immobilisierung auf Elektrodenoberflächen und Darstellung von Porphyrin-Fulleren-Dyaden

Abstract

This work describes on the one hand the synthesis of porphyrin and chlorin derivatives for the immobilization on electrode surfaces and on the other hand the synthesis of porphyrin fullerene dyads. In all syntheses hemin was used as the educt. The electrode surfaces were titanium dioxide, carbon and gold. The immobilization on titanium dioxide and gold was done by a surface coordination process of phosphonic acid side chains and disulfide groups. The immobilization on glassy carbon electrodes was achieved by electropolymerization of pyrrole groups. An important aspect of this work was the incorporation of different metal ions (iron, manganese and cobalt) into the macrocycles. The metal ions could then be reduced and oxidized by cyclovoltammetry. The modified electrodes were used as sensor for cyanide and alkyl halides. In the same way an epoxidation of ethylene with atmospheric oxygen was possible. The porphyrin fullerene dyads were synthesized for the investigation of the photosynthetic primary step, namely the light induced charge separation. The fullerene was attached via a Bingel reaction to the porphyrin. UV/Vis and luminescence measurements indicated no interaction in the ground state but an almost quantitative luminescence quenching in the excited state. Photophysical measurements showed that this is due to an electron transfer from the donor to the acceptor with a lifetime of the charge separated state of 5.2 ns.