The chiral helical structure of a copper(II) complex with a tridentate Schiff base ligand

In the title salt, catena-poly[[[aquacopper(II)]-mu-3-(2-pyridylmethyleneamino)propanoato-kappa4N,N',O:O'] perchlorate], {[Cu(C9H9N2O2)(H2O)]ClO4}n, the monomeric unit contains a square-based pyramidal Cu(II) centre. The four basal positions are occupied by a tridentate anionic Schiff base ligand which furnishes an NNO-donor set, with the fourth basal position being occupied by an O-donor atom from the carboxylate group of an adjacent Schiff base ligand. The coordination sphere is completed by a water molecule at the apical position. Interestingly, each carboxylate group in the ligand forms a syn-anti-configured bridge between two Cu(II) centres, leading to left-handed chiral helicity. The framework also exhibits O-H...O hydrogen bonds involving the water molecules and an O atom of the perchlorate anion.