Metal ion binding capability of secondary (N-methyl) versus primary (N-H) dipeptide hydroxamic acids

N-methyl substituted hydroxamic acid derivatives of L-Ala-L-Ala and L-Ala-L-Ser dipeptides were synthesized, the Fe(III), Al(III), Ni(II), Cu(II) and Zn(II) binding capabilities were studied and the effect of the replacement of hydroxamate N-H by a methyl group in metal ion binding and selectivity is discussed.95