Adsorption‐Programmed Transformation of a Two‐Dimensional Cu–Imidazolate Framework into Mn‐Integrated Catalytic Nanonetwork

ABSTRACT Metal–organic frameworks (MOFs) offer tunable platforms for water purification, yet the disposal of contaminant‐loaded frameworks creates secondary waste and limits their sustainable use. Here, a circular adsorbent‐to‐catalyst strategy is demonstrated using a freeze‐dried two‐dimensional Cu–imidazolate framework (FD‐BNMG‐1). Prepared through scalable aqueous synthesis and lyophilization, FD‐BNMG‐1 removes more than 95% of Mn(II) from water within 24 h and reaches a maximum adsorption capacity of 370 mg g −1 , the highest reported for an unmodified MOF adsorbent toward Mn(II). Cu and Mn K‐edge X‐ray absorption spectroscopy, supported by powder X‐ray diffraction, Fourier‐transform infrared spectroscopy, X‐ray photoelectron spectroscopy, scanning and transmission electron microscopy with energy‐dispersive X‐ray spectroscopy, and nitrogen sorption analysis, reveals that Mn sequestration drives substantial structural and electronic reconstruction. The Cu coordination number increases from 4.0 to 5.7, long‐range Cu order is disrupted, and an open, redox‐heterogeneous Mn‐integrated Cu coordination nanonetwork is formed. Rather than being discarded, the resulting spent material, Mn@FDB, is directly repurposed as a heterogeneous catalyst for oxidative C–O cross‐coupling reactions, affording aryl ester products in yields up to 84% and retaining activity over multiple cycles. This transformation demonstrates how adsorption can program a functional second life for contaminant‐loaded MOFs. The approach integrates pollutant capture, material transformation, and efficient catalytic valorization.