Syntheses, structures, sorption and magnetic properties of copper(II) frameworks with varied topologies

A series of copper(II) complexes have been synthesized by reactions of ligand 5-[2-(pyridin-4-yl)vinyl]isophthalic acid (H2L) with Cu(NO3)2·3H2O via the alternation of reaction temperature and solvent system. The complexes were characterized by IR, single crystal and powder X-ray diffractions, and thermogravimetric analysis. {[Cu(HL)2]·2H2O}n (1) has a ID hinged chain structure, while [CuL]n (2) is a (3,6)-connected 2D network with kgd topology. {[CuL]·0.5H2O}n (3) and [Cu2(L)2(H2O)]n (4) are (3,6)-connected 3D ScD0.33 net and flu-3,6-C2/c net, respectively. Interestingly, the E-form of free ligand is converted into Z-form during the formation of the complexes. The dehydrated complex 3 exhibits different sorption behavior for N2 and CO2. The magnetic properties of 1-4 were also investigated, and both experimental results and DFT calculations indicate that the more carboxylate groups bridging metal ions the stronger magnetic coupling observed in this system.