Two unusual (4,6)- and 8-connected metal–organic frameworks constructed from flexible 1,4-benzenebis(thioacetic acid) and pyridine-based ligands

Abstract

Two unusual metal–organic frameworks (MOFs) [CoL(4,4′-bipy)]n (1) and [Ni2L2(bpp)2(H2O)]n (2) (H2L = 1,4-benzenebis(thioacetic acid), bipy = 4,4′-bipy, bpp = 1,3-di(4-pyridyl)propane), have been synthesized and characterized by single-crystal X-ray diffraction. MOF 1 can be considered as constructed by 2D layers, which consist of left- and right-handed helical chains and is further linked by L2− ligands into a 3D (4,6)-connected network with a Schlafli symbol of (42·52·62)(42·56·64·73). MOF 2 is an unique 3D 8-connected self-penetrating network with a Schlafli symbol of (424·64), in which the dinuclear {Ni2} subunits are linked by L2− ligands to form 2D layers along the ac plane and further expanded to a 3D network by bpp ligands. The experimental magnetic susceptibility of MOFs are interpreted with the uniform 1D chain character for 1 and the dimeric nickel law for 2, yielding the exchange integral (J) values of −1.32(2) cm−1 and 1.32(2) cm−1, respectively. The exchange integrals indicate weak antiferromagnetic interactions in 1, and weak ferromagnetic interactions in 2.