Template-Assisted Synthesis of Co,Mn-MOFs with Magnetic Properties Based on Pyridinedicarboxylic Acid

To investigate the influence of organic molecules with reactive functional groups as templates on the structures of the resulting MOFs, four novel complexes based on the pyridyl carboxylic acid ligand 5-(pyridin-4-yl)­isophthalic acid (H₂pyip), namely, [Mn₃(pyip)₂(HCOO)₂(H₂O)₂]_n (1), {[Co­(pyip)­(H₂O)]·H₂O}_n (2), {[Mn₂(pyip)₂(H₂O)₄]·5H₂O}_n (3), and [Co­(pyip)­(EtOH)­(H₂O)]_n (4), have been synthesized under solvothermal conditions. In the presence of 4,4′-bipyridyl as the template, 3D coordination framework 1 with the Schläfli symbol of (4·6·7) (4²·5·6⁵·7³·8²·9·11) was obtained. Using cyanoacetic acid as the template, we obtained 2D double-layered structure 2 with the Schläfli symbol of (4³) (4⁶·6⁶·8³). 3 and 4 are prepared in the absence of a templating agent. 3 features an infinite 2D network with a 1D water chain penetrating the 1D channel and further results in a 3D supramolecule through hydrogen-bond interactions. 4 contains two independent 2D networks that are further connected to a 2D double-layered supramolecular framework by hydrogen bonds. The template-assisted method is a potential approach for obtaining specific intriguing complexes that might be difficult to access by routine synthetic methods. Magnetic investigations revealed that both 1 and 2 exhibit weak antiferromagnetic interactions mediated by pyip^2–.