Macrocyclic receptor 1 has been synthesised, as a racemate and as a single enantiomer, utilising a Stille coupling for the formation of the biphenyl portion and a macrolactamisation as the final step. The binding properties for the racemic and the homochiral macrocycle with amino acid and dipeptide derivatives, in CDCl 3 solution, have been investigated. In the case of racemic 1, addition of homochiral peptide substrates led to two distinct diastereomeric complexes, and the well separated signals for several protons in the 1 H NMR spectrum could be conveniently followed in titration experiments, allowing determination of both binding constants for the two diastereoisomeric complexes, and indicating that 1 is capable of enantioselective recognition. Titration of homochiral 1 with the same peptide substrates allowed the sense of the enantioselectivity to be determined, and experiments with a greater range of substrates indicated that 1 is particularly effective for the recognition of N-Cbz-balanyl-l-amino acids, the strongest binding being observed with N-Cbz-b-alanyll-alanine (ร DG ass 19.9 kJ mol ร1 ). No-tably the binding of N-Cbz-b-alanyl-llactic acid was considerably weaker (ร DG ass 13.1 kJ mol ร1 ), presumably due to replacement of an NH hydrogen-bond donor in the case of N-Cbz-balanyl-l-alanine with an oxygen lonepair in the case of N-Cbz-b-alanyl-llactic acid. Molecular modelling and 2 D NMR studies on the free macrocycle 1 and associated complexes did not provide conclusive evidence for the structure of the host ยฑ guest complexes, but did serve to emphasise the flexibility of 1, which despite this flexibility, shows strong, selective binding of certain peptide guests.