A novel nanoporous Cu metal–organic framework (NEM-4) with open Cu^II sites, Lewis basic nitrogen sites, and uncoordinated –COO⁻ groups exhibits both outstanding uptake capacities (in cm³ (STP) g⁻¹) for C₂H₂ (204), C₂H₄ (164.1), C₂H₆ (172.2), C₃H₆ (197.4), and C₃H₈ (196.1) and high selectivities for C₂H₂/CH₄ (63.2), C₃H₆/CH₄ (174.8), and C₃H₈/CH₄ (168.3) under ambient conditions. After eight cycles of adsorption–desorption tests, only 8.2% and 10.3% decrease in the acetylene and propene storage capacities was observed, indicating an excellent repeatability. Compared with 1 (carboxylate decorated NOTT-101), when nitrogen sites are inserted, the C₂–C₃ hydrocarbon uptakes of NEM-4 can be significantly enhanced. Grand Canonical Monte Carlo and first-principles calculations reveal that not only the open Cu^II sites but also the uncoordinated –COO⁻ groups and the nitrogen sites play significant roles in its high C₂–C₃ hydrocarbon uptakes. Moreover, the adsorption and separation of cationic dyes in NEM-4 are highly size and charge state dependent, and the adsorbed methylene blue (MB⁺) in NEM-4 can be efficiently released in an NaCl-containing CH₃OH solution. This study reveals that the combination of open metal sites, carboxylate groups, Lewis basic pyridyl sites, and appropriate pore geometry is responsible for the high adsorption/separation of light hydrocarbons in NEM-4.

中文翻译：

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通过羧酸装饰铜-有机骨架内引入路易斯碱性氮位点提高光碳氢化合物储存和分离†

一种新颖的纳米多孔铜金属-有机骨架（NEM-4）与打开的Cu ^II位点，路易斯碱性氮位点，和不协调的-COO ^-基团表现出杰出的两个吸附容量（以cm ³（STP）克^-1）对C ₂ ħ ₂（204），C ₂ H ₄（164.1），C ₂ H ₆（172.2），C ₃ H ₆（197.4）和C ₃ H ₈（196.1）以及对C ₂ H ₂ / CH ₄（63.2 ）的高选择性），C ₃ H ₆ / CH ₄（174.8）和C ₃ H ₈ / CH ₄（168.3）在环境条件下。经过八个吸附-解吸测试循环后，仅发现乙炔和丙烯的存储容量分别下降了8.2％和10.3％，这表明其重复性极好。与1（用羧酸盐修饰的NOTT-101）相比，当插入氮位时，NEM-4的C ₂ -C ₃烃吸收量可以显着提高。蒙特卡罗和第一原理计算表明，不仅是开放的铜^II网站也是不协调的-COO ^-团体和氮的点位在高C发挥作用显著₂ -C ₃碳氢化合物的吸收。此外，阳离子染料在NEM-4中的吸附和分离高度依赖于大小和电荷状态，并且可以在含NaCl的CH ₃ OH溶液中有效释放NEM-4中吸附的亚甲基蓝（MB ⁺）。这项研究表明，开放金属位点，羧酸根基团，路易斯碱性吡啶基位点和适当的孔几何形状的结合是NEM-4中轻烃高吸附/分离的原因。