Magnetic and ferroelectric properties of two Co(II) complexes based on flexible bis(imidazole) ligands

Two Co(II) complexes, [Co(bimb)(L1)2] (1) and [Co(bix)(L2)] (2) (bimb = 1,4-bis(imidazol-1–yl)-butane, bix = 1,4-bis(imidazol-1-yl-methylene)-benzene, HL1 = 3,5-dinitro-benzoic acid, H2L2 = o-phthalic acid), have been successfully prepared based on achiral flexible bis(imidazole) ligands via spontaneous resolution. Complexes 1 and 2 crystallize in the asymmetrical monoclinic with P21 and Cc space groups, respectively. Interestingly, magnetic studies reveal that complex 1 demonstrates dominant ferromagnetic behavior and complex 2 displays spin-canting behavior. More interestingly, both complexes 1 and 2 exhibit ferroelectric features representing electric hysteresis loops with the saturation polarization (Ps) of ca. 0.085 μC cm− 2 and 0.141 μC cm− 2.