Synthesis, crystal structures, and magnetic properties of three isomorphous helical coordination polymers

Three isomorphous coordination polymers of general formula {[M(H2bna)·(DMF)2·(H2O)2]·DMF}n (M = Co for 1, Mn for 2, Ni for 3, respectively, where H4bna = 2,2′-dihydroxy-[1,1′]-binaphthalene-3,3′-dicarboxylate) were synthesized under solvothermal conditions and characterized by FTIR, single crystal X-ray diffraction, thermogravimetric analysis, and X-ray power diffraction analysis. All three polymers crystallize in the same monoclinic space group P21/n. The complexes are assembled into 1D helical chains, and each adjacent helical chain of the same chirality is further connected to form a chiral layer by hydrogen bond interactions. The layers are packed in alternating left-(M) and right-handed (P) chirality arrays. Magnetic studies reveal the presence of antiferromagnetic coupling interactions in complexes 1 and 2.