| Abstract: | The complexes of cyclodisarcosyl (N,N′-dimethyldiketopiperazine) have been synthesized with copper perchlorate, lithium perchlorate, barium perchlorate, silver perchlorate, silver nitrate, and boron trifluoride. It has been shown by infrared absorption spectra that the metal cations coordinate to carbonyl groups of the peptide to form insoluble complexes. It has been suggested that the complexation takes place by ion–dipole interaction. Since a linear analog of the peptide formed no insoluble complex with the metal salts, conformation of cyclodisarcosyl seems to play an important role in the complex formation. Examination of the molecular model and X-ray analysis suggest that the copper perchlorate complex of the cyclic peptide has a “2:1-sandwich” structure. |
