Solvothermal synthesis, structures, and magnetic properties of NiII compounds directed by N,N′-bridging auxiliary ligands

Abstract

Three NiII-based metal–organic frameworks (MOFs) were synthesized from the nitro-functionalized dicarboxylate ligand 2,2′-dinitro-biphenyl-4,4′-dicarboxylate (H2dnpdc) and different N-donor bridging ligands. X-ray analyses revealed that all compounds exhibit 3D architectures. Compound 1, {Ni(dnpdc)(bipy)}n, exhibits 3D framework in which the 2D Ni(dnpdc) sheets are pillared by bipy, with a new (4,6)-connected self-penetrated net topology. In compound 2, {[Ni3(dnpdc)3(bipy)3(H2O)2]·(H2O)2}n, the binuclear Ni2(COO)2 units and mononuclear units are interlinked by the dnpdc and bipy ligands into 3D framework, which displays a rare 3-fold interpenetrated (4,6)-connected net topology. Compound 3, {Ni(dnpdc)(bpee)·H2O}n, displays a 6-fold interpenetrated diamond net based on the mononuclear NiII unit. The magnetic studies of 1 reveal that the double carboxylate bridges in the nonplanar syn-skew conformation mediate ferromagnetic interactions between the NiII ions.