Amino acid derivatives of 1,4,7-triazacyclononane : synthesis, properties and their use in the preparation of peptides with metal-binding properties

Amino acid derivatives of the cyclic polyamines 1,4,7-triazacyclononane (tacn) and piperazine have been prepared and characterised by spectroscopic, crystallographic and computational methods. Selectively protected derivatives were employed in peptide coupling reactions in solution and on solid phase to yield di-, tri- and tetra-peptides incorporating tacn and piperazine rings in their backbone. The polyamine units are envisaged to act as metal coordination sites in peptides.