The dipeptide H-Aib-l-Ala-OH ligand in copper(II) chemistry: Variation of product identity as a function of pH

The reaction between Cu(II) sources and the dipeptide H-Aib-l-Ala-OH (LH) is pH-dependent. In the “low pH” 3D coordination polymer {[CuClL](H2O)2.5}n, the monoanionic dipeptide behaves as a tridentate bridging N(amino), O(peptide), O(carboxylate) ligand, while the dianionic dipeptide exhibits the tetradentate bridging N(amino), N(peptide), O(carboxylate), O′ carboxylate behaviour in the “higher pH” 1D complex {[Cu(H−1L)(EtOH)](EtOH)}n.