Microwave-assisted synthesis of a series of lanthanide metal-organic frameworks and gas sorption properties.

A series of isostructural microporous lanthanide metal-organic frameworks (MOFs) formulated as [Ln(2)(TPO)(2)(HCOO)]·(Me(2)NH(2))·(DMF)(4)·(H(2)O)(6) {Ln = Y (1), Sm (2), Eu (3), Gd (4), Tb (5), Dy (6), Ho (7), Er (8), Tm (9), Yb (10), and Lu (11); H(3)TPO = tris-(4-carboxylphenyl)phosphineoxide; DMF = N,N-dimethylformamide} has been synthesized under microwave-assisted solvothermal reaction for 30 min. Alternatively, if a conventional solvothermal reaction is carried out under the same temperature, a much longer time (3 days) is needed for the same phase in similar yield. Structure analysis reveals that the framework is a 4,8-connected network with point symbol (4(10)·6(16)·8(2)) (4(5)·6)(2), which is the subnet of alb net. Thermal gravimetric analyses performed on as-synthesized MOFs reveal that the frameworks have high thermal stability. The luminescent properties of 2, 3, 5, and 6 were investigated and show characteristic emissions for Sm(III), Eu(III), Tb(III), and Dy(III) at room temperature, respectively. Gas sorption properties of 1 and 3 were studied by experimentally measuring nitrogen, argon, carbon dioxide, methane, and hydrogen sorption isotherms. The resulting materials show high and preferential CO(2) adsorption over N(2) gas at ambient temperature, indicating that the present materials can be applied in a CO(2) capture process.