Abstract 1 H and 19 F NMR spectra were obtained for six Schiff bases (aldimines) formed by pyridoxal-5′-phosphate (PLP) with four fluorinated or their two parent non-fluorinated α- amino acids (phenylalanine and α-aminobutyric acid). pK A Values were derived from 1 H and 19 F titration curves. The imine nitrogen of the aldimines is very basic (∼ 13) and sensitive to the electron withdrawing effect of fluorine. The pyridine nitrogen is less basic ...
