A multifunctional manganese coordination polymer with polar solvent-responsive tunable dielectric properties and selective catalysis

A dielectric-tunable coordination polymer, [Mn₂(SBA)₂(Phen)(DMF)]·2DMF (Mn-CP1), has been synthesized via solvothermal method using manganese salt, 4,4′-sulfonyldibenzoic acid (H₂SBA), 1,10-phenanthroline (Phen), and DMF–MeOH solvent system. Single-crystal X-ray diffraction of Mn-CP1 revealed a well-defined 2D square-channel framework constructed from rare tetranuclear {Mn₄N₄O₁₈} secondary building units within the triclinic P space group. Mn-CP1 exhibited a high dielectric constant at room temperature (κ ≈ 12.2 at 1 kHz), attributed to the combined effects of its polar metal-carboxylate framework and the orientational polarization of coordinated and lattice DMF molecules. Upon thermal desolvation of Mn-CP1, the dielectric constant sharply decreases to κ ≈ 4.4, demonstrating polar solvent-responsive dielectric tunability. Impedance spectroscopy (Z′ and Z′′) further confirmed that observed changes in dielectric properties arise from intrinsic bulk properties and framework host interactions. In addition to dielectric behaviour, Mn-CP1 also displayed excellent catalytic performance for the selective oxidation of methylarenes to arylaldehydes under mild conditions, achieving 83% conversion and 88% selectivity for toluene using H₂O₂ as a green oxidant. These results highlight Mn-CP1 as a multifunctional material that combines solvent-tunable dielectric behavior with catalytic efficiency, offering strong potential for applications in electronic devices and sustainable catalysis.