Porphyrins and phthalocyanines of transition metals are good catalysts for many redox reactions [<A HREF="#1">1</A>-<A HREF="#7">7</A>]. In order to increase their catalytic activity it is often necessary to modify the macrocycle with donor or acceptor substituents making the species more reductive or oxidant depending on the analyte. However, this process is a one-way modification, because the molecule enhances or diminishes the electronic density of the metal by the substituent effect