Design of Ligands That Stabilize Cu(I) and Shift the Reduction Potential of the Cu(II/I) Couple Cathodically in Aqueous Solutions.

The ligands R(2)NCH(2)CH(2)N(R)CH(2)CH(2)N(R)CH(2)CH=CH(2), where R = H, CH(3), were synthesized. The stability constants of their complexes with Cu(II) and Cu(I) in aqueous solutions were determined. Both ligands stabilize Cu(I) in aqueous solutions, though the reduction potentials of both (CuL(i)())(2+/+) couples are shifted cathodically in comparison to the Cu(2+/+)(aq) couple.