A straightforward synthesis of a C 3 -symmetric imidazolecontaining macrocyclic peptide with three hydroxyquinoline side arms is presented.

SummaryA facile synthesis of a highly preorganized tripodal enterobactine-type ligand 1a-H3 consisting of a chiral C 3-symmetric macrocyclic peptide and three tridentate 2-amido-8-hydroxyquinoline coordinating units is presented. Complex formation with various metal ions (Al3+, Ga3+, Fe3+, La3+ and Eu3+) was investigated by spectrophotometric methods. Only in the case of La3+ and Eu3+ were well defined 1 : 1 complexes formed. On the basis of CD spectroscopy and DFT calculations the configuration at the metal centre of the La3+ complex was determined to show Λ helicity. The coordination compounds [(1a)Ln] presented should be prototypes for further lanthanide(III) complexes with an enterobactine analogue binding situation.