Solvent-controlled structural diversity observed in three Cu(ii) MOFs with a 2,2′-dinitro-biphenyl-4,4′-dicarboxylate ligand: synthesis, structures and magnetism†
Abstract
Three extended three-dimensional CuII-based metal–organic frameworks (MOFs) have been separated successfully from reactions of 2,2′-dinitro-biphenyl-4,4′-dicarboxylate (H2dnpdc) and Cu(NO3)2 under controllable solvothermal conditions. The resulting structures of the MOFs are highly dependent on the solvent used during the synthesis. Compound 1, [Cu(dnpdc)(H2O)]n·(DMA)4(H2O)2, is a two-fold interpenetrated three-dimensional framework with NbO topology based on a binuclear [Cu2(O2C)4] “paddle-wheel” secondary building unit. In compound 2, [Cu9(dnpdc)6(OH)6(H2O)2]n·{(DMF)8(EtOH)3(H2O)12}n, the complicated one-dimensional [Cu(OH)(OCO)]n chains are cross-linked into three-dimensional frameworks by the dnpdc2− ligands. Compound 3, {Cu4(dnpdc)3(OH)2(py)4}n, displays three-dimensional nets with pcu topology based on 6-connected [Cu(μ3-OH)2(OCO)4] tetracopper clusters. Magnetically, compound 2 exhibits homo-spin topological ferrimagnetic behavior. Compound 3 features antiferromagnetic interactions mediated by μ3-OH and syn–syn-OCO heterobridges between the CuII ions.