A 3D ferroelectric Co(II) polymer showing (3,5)-connected hms topology with 2-fold interpenetration

The hydrothermal reaction of CoCl2·6H2O, 4,4′-(ethene-1,2-diyl)dibenzoic acid (H2L) and 1,3,5-tris(imidazol-1-ylmethyl)-2,4,6-trimethylbenzene (titb) generates a new three-dimensional (3D) coordination polymer [Co(titb)(L)]·3H2O (1). Compound 1 crystallizes in a noncentrosymmetric Cc space group and the topology analysis suggests it features a rare binodal (3,5)-connected (63)(69·8) hms net with 2-fold interpenetration, constructed by the 2D Co(titb)2 + sheet pillared by L ligands via coordination to the Co atoms. Furthermore, the thermal and ferroelectric properties of 1 have also been studied.