Three-Dimensional Honeycomb-like Pb-MOF with Multiple Sites for Selective Gas Adsorption and Efficient CO ₂ Catalytic Conversion

One novel honeycomb-like Pb²⁺-based metal-organic framework [Pb(dtzip)_0.5(H₂O)]·NMP·2H₂O (H₄dtzip = 4,6-di(1H-tetrazol-5-yl) isophthalic acid, NMP = <i>N</i>-methyl-2-pyrrolidone) was synthesized through solvothermal reaction of Pb²⁺ ions with the azolate-carboxylate linker H₄dtzip, which displays hexagonal channels with multiple accessible metal centers and N sites. Desolvated framework Pb(dtzip)_0.5 shows high porosity and significant adsorption selectivity, achieving effective separation for C₂H₂/CO₂, CO₂/CH₄, and C₂H₂/CH₄ mixtures, respectively. The exposed Pb²⁺ Lewis acidic sites in Pb(dtzip)_0.5 lead to efficient heterogeneous catalysis for CO₂-epoxide cycloaddition, producing cyclic carbonates in high yields. This unusual material demonstrates remarkable substrate versatility, achieving quantitative conversion (99%) for simple substrates such as 1,2-epoxybutane, while maintaining excellent performance (>85% conversion) even with sterically demanding substrates. The role of metal centers and accessible organic sites in selective adsorption and catalytic reactions was deeply investigated through molecular simulations.