Two metal-organic frameworks constructed from one-dimensional cobalt(II) ferrimagnetic chains with alternating antiferromagnetic/ferromagnetic and AF/AF/FM interaction: synthesis, structures, and magnetic properties.

Here, we report two three-dimensional metal-organic frameworks of formula [Co(2)(4-ptz)(2)(bpp)(N(3))(2)](n) (1) and [Co(3)(OH)(2)(bdt)(2)(bpp)(2)(H(2)O)(2)](n) (2), which were synthesized by hydrothermal reaction from the respective tetrazole ligand (5-(4-pyridyl)tetrazole (4-H-ptz) for 1 and 5,5'-(1,4-phenylene)bis(1-H-tetrazole) (H(2)bdt) for 2), long and flexible pyridyl-containing ligand 1,3-bi(4-pyridyl)propane (bpp), NaN(3), and CoCl(2). Both 1 and 2 consist of well-isolated one-dimensional cobalt(II) alternating chains further linked by the bpp and/or the tetrazole ligand, while their chain structures are totally different. The chains of 1 are formed by Co(2+) ions bridged by single μ-EE-N(3) and triple (μ-EO-N(3))(μ-tetrazole)(2) alternately, whereas the Co(2+) ions are bridged by μ(3)-OH to form Co(3)(OH)(2) chains in compound 2. Magnetic measurements demonstrate that compound 1 contains an alternating antiferromagnetic (AF)/ferromagnetic (FM) ferrimagnetic chain, while compound 2 exhibits the coexistence of spin canting, slow magnetic dynamics, and finite-size effect, with alternating AF/AF/FM ferrimagnetic chains.