Controlling Interpenetration in Electroactive Co(II) Frameworks Based on the Tris(4-(pyridin-4-yl)phenyl)amine Ligand

Abstract

Control over the degree of interpenetration within metal–organic frameworks has important implications for the application of these materials in numerous areas ranging from gas storage to chemical separations. In this work, the degree of interpenetration was controlled in a series of three Co2+ frameworks with the redox-active tris(4-(pyridin-4-yl)phenyl)amine (NPy3) ligand, where the steric bulk of the dicarboxylate coligand (1,4-benzenedicarboxylate (bdc), 2,5-dimethyl-1,4-benzenedicarboxylate (dmbdc), or 2,3,5,6-tetramethyl-1,4-benzenedicarboxylate (tmbdc)) was increased by the addition of methyl groups to the phenyl core. The use of less sterically hindered carboxylates (bdc, dmbdc) resulted in 3-fold interpenetrated three-dimensional (3D) networks, while use of the tmbdc ligand resulted in a 3D non-interpenetrated structure. The redox activity of the NPy3 ligand was retained within the framework as elucidated from electrochemical and spectral measurements.