Synthese von Porphyrinen zur Immobilisierung an Elektrodenoberflächen - Elektrochemische Sensoren und künstliche Photosynthesesysteme

Porphyrin fullerene dyads are widely used to study light induced electron and energy transfer. In our studies we synthesized new porphyrin fullerene dyads starting from naturally occuring porphyrins as donors and fullerene C60 as acceptor moieties.Deuteroporphyrin-IX-dimethylester which can be easily obtained from the red blood pigment heme is the ideal starting point of the synthetic approaches.Some of the dyads were prepared via [4 :img:=Plus2.gif:/img: 2] cycloaddition between porphyrin donor and fullerene acceptor. For the possibility of generating a photo current a porphyrin fullerene dyad was functionalized with lipoic acid anchor groups for immobilisation on the surface of a gold electrode.Other porphyrin fullerene dyads were synthezised via [3 :img:=Plus2.gif:/img: 2] cycloaddition between formyl deuteroporphyrin and fullerene C60 by means of N-methylglycine.Novel Zn(II)-, Co(II)-, and Fe(III)-porphyrins were synthesized by formation of cystamin amide derivatives. The obtained metallodeuteroporphyrins bearing disulfide moieties could be immobilized on gold surfaces. Physical properties and electrochemical behaviour of the modified electrodes were characterized by cyclovoltammetry, ellipsometry, electrochemical quartz crystal microbalance (EQCM) and X-ray photoelectron spectroscopy (XPS). Fe(III)-porphyrin modified electrodes show catalytic activities in the electrochemical reduction of oxygen.