Three‐Dimensional Co‐ and Mn‐MOFs Containing a C 2 h ‐Symmetric Terphenyl‐3,3′‐dicarboxylate Linker and Their Magnetic Properties

We report herein two new isostructural, three‐dimensional (3D) MOFs with the general formula [M(3,3′‐tpdc)(dmf)] [M = Co II ( I ), Mn II ( II )] resulting from the assembly of a metal ion and the C 2 h ‐symmetric ditopic bridging ligand terphenyl‐3,3′‐dicarboxylate (3,3′‐tpdc). Both isostructural MOFs crystallize in the monoclinic space group C 2/ c . The metal ion is coordinated by four O carboxylate (η 1 :η 1 :µ 2 ) and two µ 2 ‐O dmf atoms in a distorted octahedral geometry. The metal centers are interconnected through bridging 3,3′‐tpdc and dmf ligands to form a 1D chain. The resulting 1D metal chains are further interconnected by 3,3′‐tpdc ligands to form 3D frameworks without porosity. The thermolabile dmf bridging ligands were easily removed by heating at 180 °C under vacuum for 5 h. The activated MOFs I and II exhibited very low gas uptake of N 2 , CO 2 , and H 2 after removal of the dmf bridging ligands. The encapsulation of iodine guest molecules by the activated I and II was also investigated. The crystal structure of iodine‐encapsulated II was also elucidated. The coordination environment of the Mn II atom in II changed as a result of the loss of dmf bridging ligands. The as‐prepared MOFs I and II exhibit weak antiferromagnetic interactions in their 1D metal chains; these magnetic interactions should mainly occur between the metal ions bridged by the short carboxylate‐based ligand and dmf oxygen atoms. Thermal removal of the bridging dmf molecules led to a change in the Mn ··· Mn distances in the 1D chains of II that also affected its magnetic properties.