Deuterium isotope effects on 13C chemical shifts of lithium salts of Schiff bases amino acids

The deuterium isotope effects on 13C chemical shift of Schiff bases lithium salts, derivatives of amino acids (glycine, l-alanine, l-phenylalanine, l-valine, l-leucine, l-isoleucine and l-methionine) and 2-hydroxynaphthaldehyde in D2O as well as UV-vis spectra in different solvents have been measured. The results have shown that the lithium salts of the Schiff bases exist in the proton transferred NH form with intramolecular hydrogen bond in water.