Metal-organic frameworks with double channels for rapid and reversible adsorption of 1,2-ethylenediamine and gases

Selective liquid and gas adsorptions are important for environmental control and industrial process. Here unique porous lanthanide–organic frameworks of [Ln2(1,3-pdta)2(H2O)2]n2n− {Ln = La (1), Ce (2), Pr (3), and Nd (4), 1,3-pdta = CH2[CH2N(CH2CO2H)2]2} are template-synthesized by 1,2-ethylenediamine and fully characterized, which possess hydrophobic and hydrophilic open channels simultaneously. The skeletons are stable up to 200 °C. Obvious downfield shifts have been observed for 1,2-ethylenediamine in the confined channel with solid state 13C NMR measurement. The ammonium salt is directly used for the removal of 1,2-ethylenediamine in water. Its saturated adsorption capacity reaches in less than one minute, and can be regenerated easily with a similar uptake capacity. Moreover, the materials can also selectively adsorb O2 CH4, and CO2 respectively, which is useful for CO2/CH4, CO2/H2, and O2/N2 separation. The combined hydrophobic and hydrophilic open channels of the lanthanides make them promising fun...