Two new entangled Cu(II)-based metal–organic frameworks (MOFs) have been synthesized, namely [Cu(BDC)(BPDB)_0.5]_n (PNU-25) and [Cu(NH₂-BDC)(BPDB)_0.5]_n (PNU-25-NH₂), using a H₂O–MeOH solvent mixture. Both the PNU-25 and PNU-25-NH₂ MOF materials were characterized by various analytical techniques, and their potential for catalyzing CO₂ fixation into cyclic carbonates at an atmospheric pressure, at a low reaction temperature, and in the neat conditions was demonstrated. The amine-functionalized PNU-25-NH₂ exhibited a significantly high conversion of epichlorohydrin (ECH) at 1 bar of CO₂ pressure, at 55 °C, and with a moderate catalyst amount (1 mol%), with over 99% selectivity toward the corresponding cyclic carbonate of ECH. The superior catalytic activity of PNU-25-NH₂ may be attributed to its high amount of acidic–basic sites and large BET surface area in comparison with the PNU-25. The PNU-25-NH₂ catalyst could be reused up to four cycles without compromising its structural integrity and the ECH conversion. The reaction mechanism of the CO₂ and ECH cycloaddition reaction mediated by PNU-25-NH₂ was investigated in detail, based on the experimental inferences and periodic calculations of density functional theory (DFT). The energy barrier of the rate-determining step of the PNU-25-NH₂/TBAB-catalyzed reaction was significantly lower than the barriers of the rate-determining steps of non-catalyzed and TBAB-catalyzed reactions.

中文翻译：

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新型铜基金属-有机骨架的简便绿色合成：CO ₂固定反应的实验和理论研究

已经合成了两个新的基于纠缠的基于Cu（II）的金属有机骨架（MOF），即[Cu（BDC）（BPDB）_0.5 ] _n（PNU-25）和[Cu（NH ₂ -BDC）（BPDB）_0.5 ] _n（PNU-25-NH ₂），使用H ₂ O-MeOH溶剂混合物。PNU-25和PNU-25-NH ₂ MOF材料都通过各种分析技术进行了表征，并证明了它们在大气压，低反应温度和纯净条件下催化CO ₂固定成环状碳酸酯的潜力。。胺官能化的PNU-25-NH ₂在1 bar CO ₂压力，55°C和适量催化剂用量（1 mol％）下，环氧氯丙烷（ECH）的表氯醇（ECH）转化率非常高，对ECH的相应环状碳酸酯的选择性超过99％。与PNU-25相比，PNU-25-NH ₂的优异催化活性可能归因于其大量的酸碱性位点和较大的BET表面积。PNU-25-NH ₂催化剂最多可重复使用四个周期，而不会影响其结构完整性和ECH转化率。PNU-25-NH ₂介导的CO ₂和ECH环加成反应的反应机理根据实验推论和密度泛函理论（DFT）的周期性计算，进行了详细研究。PNU-25-NH ₂ / TBAB催化的反应速率确定步骤的能垒显着低于非催化和TBAB催化的反应速率确定步骤的能垒。