Three-Dimensional Porous Metal−Organic Frameworks Exhibiting Metamagnetic Behaviors: Synthesis, Structure, Adsorption, and Magnetic Properties

Two isomorphous 3D porous metamagnets, {[M₆(N₃)₁₂L₆]·(H₂O)₁₃}_∞ (M = Ni^II, 1; Co^II, 2), have been constructed from 2-(1,3,4-thiadiazol-2-ylthio)acetic acid (HL), with azido as the auxiliary ligand. Single-crystal X-ray analysis indicates that the complexes possess hexagonal channels with dimensions of about 8.3 Å × 8.3 Å along the c axis and void space of about 25% per cell volume. Hydrogen adsorption measurements at 740 Torr and 77 K reveal that hydrogen uptakes of 0.68 and 0.83 wt % were observed in 1 and 2, respectively, with BET surface areas of 309 and 328 m²/g. Magnetic measurement reveals that both of them exhibit global metamagnetic behaviors resulted from strong intrachain ferromagnetic couplings and weak interchain antiferromagnetic interactions, with critical fields of 22 kOe and 6 kOe for 1 and 2, respectively.