Microporous coordination polymers of cobalt(II) and manganese(II) 2,6-naphthalenedicarboxylate: preparations, structures and gas sorptive and magnetic properties

Two isostructural coordination polymers M3(NDC)3(DMF)4 (M = Co (1), Mn (2); H2NDC = 2,6-naphthalenedicarboxylic acid; DMF = N,N′-dimethylformamide) were prepared through conventional and microwave-assisted solvothermal methods. Single crystal X-ray analysis indicated that both complexes crystallized in the monoclinic system with space group C2/c. Powder X-ray diffraction (PXRD) patterns of the bulk samples for the two complexes obtained from microwave-assisted solvothermal syntheses matched well with the simulated ones from the single crystal data as well as the ones prepared by conventional solvothermal method. These microporous cobalt(II) and manganese(II) coordination polymers undergo reversible structural change upon desolvating, giving stable microporous frameworks containing unsaturated metal sites, and resolvating. The desolvated complexes showed different nitrogen gas adsorption capabilities but very close hydrogen adsorption behaviors. Variable-temperature magnetic susceptibilities of 1 and 2 revealed the weak antiferromagnetic coupling between the adjacent metal ions bridged by carboxylate.