A series of dysprosium-based hydrogen-bonded organic frameworks (Dy-HOFs): thermally triggered off → on conversion of a single-ion magnet

The discovery of hydrogen-bonded organic frameworks (HOFs) has offered new opportunities for the expansion of porous materials. The field of HOFs has also introduced a new challenge-the design and synthesis of lanthanide HOFs (Ln-HOFs). Given that Ln complexes have various coordination modes, complex coordination structures, and irregular shapes, Ln-HOFs are extremely difficult to construct. In this study, a series of dysprosium-based HOFs (Dy-HOFs), namely, [Dy(L-1)(3)(CH3OH)center dot Phen](n) (Cl-1) and [Dy(L-2)(3)(CH3OH)center dot Phen](n) (Br-1), were designed and synthesized for the first time under solvothermal conditions of 5,7-dichloro/dibromo-2-methyl-8-quinolinol (L-1/L-2), Dy(NO3)(3)center dot 6H(2)O, and 2,9-dimethyl-1,10-phenanthroline (Phen). The porous Cl-1 (Br-1) was filled with Phen molecules linked by various supramolecular weak interactions. After Cl-1 (Br-1) was incubated at 260 degrees C for 2 h under a N-2 atmosphere, we found that only free Phen in the pores disappeared and Cl-2 (Br-2) was obtained. Magnetic characterization studies revealed that Cl-1 and Br-1 exhibited inconspicuous slow relaxation behavior. Unexpectedly, Cl-2 and Br-2 exhibited an evident single-ion magnetic (SIM) behavior, and their energy barriers were 97 and 87 K, respectively. We achieved the off -> on SIM conversion of the Dy-HOFs for the first time.