Fully meta-Substituted 4,4′-Biphenyldicarboxylate-Based Metal–Organic Frameworks: Synthesis, Structures, and Catalytic Activities

Article abstract of DOI:10.1002/ejic.201601242

Fully meta-substituted 2,2′,6,6′-tetramethoxy-4,4′-biphenyldicarboxylic acid (H₂L) was synthesized and applied in the construction of three metal–organic frameworks (MOFs), {[Cu₃L₃(H₂O)₂(DMF)]_n (1), [Zn₄OL₃]_n (2), and [Zn₄OL₃(H₂O)(DEF)]_n (3)}. For 1, the approximately vertical twist of two benzene rings in L leads to the formation of a twofold-interpenetrated 3D structure with 1D open channels (11 × 15 ?). MOFs 2 and 3 have classical twofold-interpenetrated isoreticular MOF structures, and reversible transformation of the oxozinc carboxylate clusters of 2 and 3 could be realized via a solvent-exchange-induced single-crystal-to-single-crystal pathway, which provides direct structural evidence for a Zn₄O core as Lewis acidic site in MOFs. Desolvated framework 1′ exhibits high permanent porosity (Langmuir surface area = 555 m²/g), high thermal stability (up to 300 °C), and highly active catalytic properties for cyanosilylation and olefin epoxidation. MOF 2 exhibits moderate carbon dioxide uptake ability and can efficiently catalyze the cycloaddition of CO₂ with epoxides under mild conditions.