Abstract
<jats:p>A coordination-tuned MnOH-[HEA][HCOO] metal–ionic liquid framework achieves 91% conversion of 1,4-dimethoxybenzene and 93% lignin conversion, demonstrating the catalytic advantage of distorted Mn–O sites for selective C–C/C–O bond cleavage. Metal–ionic liquid frameworks (MIFs) combine the catalytic diversity of metal centers with the tunable solvation and hydrogen-bonding environment of ionic liquids. Here, Mn-based MIFs were prepared through an indirect coordination strategy using hydroxyethylammonium formate, [HEA][HCOO], and coordination-directing agents to tune the local Mn–O geometry. Ethanol and hydrogen peroxide CDAs generated MnOH-[HEA][HCOO] and MnOOH-[HEA][HCOO], respectively, from the parent Mn-[HEA][HCOO] framework. XRD, Raman spectroscopy, XPS, and XAS confirm kempite-phase frameworks in which coordination tuning induces lattice contraction, Mn–O distortion, and centrosymmetric loss around Mn–O sites. Among the catalysts, MnOH-[HEA][HCOO] showed the highest activity toward the probe substrate and was subsequently applied to alkali lignin depolymerization. Under acetic acid conditions at 4 h, the catalyst favored aromatic ketone formation, including 1-(3,4-dimethoxyphenyl)ethan-1-one, alongside oxygenated aromatic products such as 2-(2-methoxyphenyl)propan-1-ol, 2,3,4-trimethoxybenzaldehyde, and homovanillic acid. These findings establish coordination tuning of Mn–O sites in MIFs as a promising design principle for selective lignin valorization.</jats:p>