Werner-type metal complexes of potato starch

It was shown that potato starch formed Werner-type complexes. In these complexes a metal atom is ligated by the lone electron pairs of hydroxyl groups from d-glucose units and phosphate groups in starch. Acetate, chloride and nitrate were counter-ions to the transition metal atoms. The metal cations bound preferentially to the phosphoric acid moiety of amylopectin, but secondarily they were co-ordinated by the hydroxyl groups of the d-glucose units. This resulted in the formation of clathrate cages in which a significant number of the water molecules were trapped. Such structures were able to coordinate further metal cations. Only Mn(II) and Co(II) ions, with acetate counter-ions, neither formed clathrate cages nor were coordinated by the hydroxyl groups of the d-glucose of starch.