| Abstract | The preparations of the five ferrocenoyl-oligopeptides, Fc---Pro---OBzl (1), Fc---Pro2---OBzl (2), Fc---Pro3---OBzl (3), Fc---Pro4---OBzl (4) and Fc---Pro2---Phe---OBzl (5) are described. Crystallographic studies show that the Fc-oligoprolines 1-4 adopt a helical polyproline II structure having all prolines in a mutually trans-conformation. This structure is maintained in MeCN and CHCl3 solutions, as was shown by NMR methods. Chemical and magnetic similarities among the proline residues render spectral assignment by conventional 1D 1H-NMR spectroscopy impossible. However, a combination of 2D NMR techniques allowed us to unequivocally assign all signals. The redox potential of the Fc-group attached to the oligoproline chain is sensitive to the sequence and length of the oligopeptide. With growing peptide length, the molecule becomes easier to oxidize. |
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