Ferroelectricity based on coordination compound: Transition metal Co(II) sulfates templated by homochiral 2-methylpiperazine (C5H14N2)[Co(H2O)6](SO4)2

Two coordination compounds (C5H14N2)[Co(H2O)6](SO4)2 (1 and 2) were prepared by reacting homochiral (R)-2-methylpiperazine with cobalt sulfate heptahydrate with a solution method in the presence of concentrated sulfuric acid (H2SO4). They are polymorphs, with hydrogen bonding structures differing obviously. Compound 1 displays ferroelectric behaviors.