Cu(II) MOFs Based on Bipyridyls: Topology, Magnetism, and Exploring Sensing Ability toward Multiple Nitroaromatic Explosives

In this work, a series of three copper(II) metal-organic frameworks (MOFs), [Cu(4,4′-DP)Cl]n (1), [Cu(4,4′-DP)0.5Cl]n (2), and [Cu(4,4′-TMDP)Cl]n (3) (4,4′-DP = 4,4′-dipyridyl, 4,4′-TMDP = 4,4′-trimethylenedipyridyl), is designed and synthesized under solvothermal conditions. Crystallographic investigations reveal that 1 and 2 have tetrahedral and 3 has octahedral environment around the Cu(II) ion. By varying the solvent conditions and ligand derivatives, the topology can be interestingly tuned. TOPOS Pro provides topological conclusions that 1 is stabilized by unusual 2D + 2D → 3D polycatenation of layers lying in (110) and (110) planes with dihedral angle of 90° showing altogether fes, hcb, and sql topologies. On the other hand, 2 exhibits a bey (3,4-c net) topology and 3 shows 4-fold interpenetration with the dia topology. The dc measurements for 1–3 performed on polycrystalline samples in a 0.1 T field confirm strong ferromagnetic behaviors for 1 and 2 and moderate antiferromagnetic behavior for 3. T...