Magnetic behaviour of 3D metal−organic frameworks constructed via 1,2,4,5-benzenetetracarboxylate linker and 4f Ce(III) or 3d Fe(III) metal nodes

Herein, a pair of 3D MOFs were constructed by the solvothermal reactions of the 1,2,4,5-benzenetetracarboxylic acid (H4btc) with Ce(NO3)3·6H2O or FeCl2·4H2O. Single-crystal X-ray diffraction analysis revealed that the Ce-based MOF {[Ce(H2btc)0.5(btc)0.5]·H2O}n (1) crystallized in a triclinic system (PĪ) to form a 3D network due to two different coordination modes of btc− with Ce(III). While, Fe-based MOF (2) adopted a 3D crystal structure within a monoclinic space group (C2/c), consuming only one type of btc− coordination. Thermogravimetric analyses showed that both compounds 1 and 2 were highly stable up to ~ 300 °C after removal of water molecules. Temperature dependent magnetic study indicated paramagnetic behaviour for compound 1, while compound 2 exhibited weak antiferromagnetic couplings; these differencing behaviour for compound 1 and 2 were driven by their respective 4f rare earths and 3d transition metal ions. This study on magnetic transitions in different metals based MOFs will pave the way to further investigate the role of metal ions and their concentrations in controlling the magnetic orderings in MOFs.