Conformational investigations of bis(α-aminoalkyl)phosphinic acids and studies of the stability of their complexes with Cu(II)

Conformational investigations of a group of bis(α-aminoalkyl)phosphinic acids were performed by use of NMR spectroscopy and theoretical calculations. In the case of one of the studied compounds, substituted with aminobenzyl and amino(p-chlorobenzyl) moieties, a pH-dependent equilibrium between conformers, stabilized by intermolecular hydrogen bonds was observed. Potentiometric studies proved that these molecules formed stable complexes with copper(II) ions, where stoichiometry was 1:1 and 1:2 depending on pH of their aqueous solution.