Porphyrin derivatives as water-soluble receptors for peptides†

The porphyrin–crown ether derivatives described here exhibit affinities to unprotected peptides of hitherto unknown magnitude in aqueous solution; the optical signal built-in to porphyrin receptors makes these applicable also to sensor techniques; the results can also form the basis of new catalytic systems, e.g. for the catalytic oxidation of peptides (such as tyrosinase models).