Flexible and rigid dicarboxylic acids enable the assembly of achiral and chiral 3D Co(ii) metal-organic frameworks.

Two novel 3D Co(ii) metal-organic frameworks induced by flexible and rigid dicarboxylic acids [Co3(μ3-OH)(1,4-ttb)3(sa)]·3H2O (1) and Co2(μ3-OH)(1,4-ttb)(4,4'-bpdc) (2) (1,4-ttb = 1-(tetrazo-5-yl)-4-(triazo-1-yl)benzene, sa = succinic acid and 4,4'-bpdc = biphenyl-4,4'-dicarboxylic acid) have been successfully synthesized and characterized via X-ray single-crystal diffraction, powder X-ray diffraction (PXRD), FT-IR spectroscopy and TG analyses. In the structures of the compounds 1 and 2, the main ligand 1,4-ttb coordinates with Co(ii) ions to form 3D host frameworks with different cavities, and the auxiliary ligands sa and 4,4'-bpdc fill the 3D cavities. More strikingly, compound 2 is a chiral 3D metal-organic framework, in which 4,4'-bpdc acts as a rigid achiral ligand. Additionally, the electrochemical properties and magnetic properties of compounds 1 and 2 have been investigated.