Helical Porphyrinoids: Incorporation of Ferrocene Subunits into Macrocyclic Structures

Stępień M.; Simkowa I.; Latos-Grażyński, L.
Eur. J. Org. Chem. 2008, 2601–2611 | view at publisher's site

Ferrocene-containing porphyrinoids have been synthesized in which ferrocene-1,1'-diyl units are linked to a dipyrrin or thiatripyrrin to form macrocyclic structures. NMR spectroscopic evidence shows that these new systems adopt helical conformations that undergo an inversion process in solution. In addition, small amounts of unexpected scrambling products have been isolated and characterized, namely a dipyrrin-bisferrocenophane and two expanded bis(ferrocene) macrocycles. The formation of these systems, which contain macrocyclic rings of different sizes, is a consequence of the structural flexibility of the ferrocene unit. Cyclic voltammetry shows that ferrocene oxidation is reversible in all the systems reported here, and that it is finely tuned by the properties of the ring system. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)