Synthesis, Conformation, and Interactions with Small Molecules of Bis (Cyclic Dipeptides)

Bis (cyclic dipeptides), cyclo and S, S′‐bis(cyclo(hemiCys‐Pro)), were synthesized. These bis (cyclic dipeptides) very efficiently formed complexes with Ba2+ and Na+ owing to intramolecular cooperation of two cyclicdipeptide moieties, the bis‐effect. Cyclo stacked sodium 8‐anilino‐1‐naphthalensulfonate in aqueous solution. These properties of complexation were controlled by the nature of the bridge connecting two cyclic dipeptide moieties. The geometry of the complex between S, S′‐bis (cyclo (hemiCys‐Pro)) and metal ion was investigated with the help of circular dichroism, nuclear magnetic resonance, and Raman spectroscopy.