Experimental study of the influence of specific intramolecular interactions on the conformation of model molecules. (Peptides and oligopeptides).

ABSTRACT Several experimental methods have been used for studying the conformations taken by dipeptidic molecules when dissolved, at a very low concentration. in an inactive solvent such as carbon tetrachloride. Through systematic investigations performed by infrared and nmr spectroscopy. it has been possible to obtain accurate data about these conformations and to compare with the results of various theoretical treatments. Several typical examples are reported which concern aminoacid derivatives containing a paraffinic. an aromatic or a polar side substituent. It appears that the conformations taken by such molecules are mainly determined by specific intramolecular forces. These results agree only with the conclusions of the theoretical calculations in which such interactions have been considered.