13C NMR Spectroscopic Studies of Intra- and Intermolecular Interactions of Amino Acid Derivatives and Peptide Derivatives in Solutions

13C NMR spectroscopic investigations were conducted for various amino acid derivatives and peptides. It was observed that chemical shifts of the carbonyl carbons are correlated with solvent polarities, but extent depends on structures. The size functional groups inter- intra-molecular hydrogen bonding appear to be major contributors this tendency.