Two 3D chiral coordination polymers with 4-connected 6⁶ topological net: synthesis, structure and magnetic properties

The hydrothermal reaction of Co(II)/Cu(II), 5-hydroxyisophthalic acid and dipyridophenazine leads to the generation of two 3D chiral coordination polymers, [M(hip)(DPPZ)]_n (M = Co(1), Cu(2), H₂hip = 5-hydroxyisophthalic acid, DPPZ = dipyridophenazine), which contain M-hip-M helical chains (M = Co, Cu) and possess a new four-connected 6⁶ topological net. The resulting crystals were not a racemic mixture but an enantiomeric excess, which was confirmed by the measurement of optical rotation of the bulk samples using solid state vibrational circular dichroism (VCD) and solid circular dichroism (CD) based on the large crystals from one crystallization. The magnetic properties of 1 and 2 have been investigated by variable-temperature magnetic susceptibility and magnetization measurements, and the results reveal that antiferromagnetic interactions exist in 1 and 2.