Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University , Yoshida, Sakyo-ku, Kyoto 606-8501, Japan.
Department of Applied Chemistry, Graduate School of Engineering, Nagoya University , Chikusa-ku, Nagoya 464-8603, Japan.
J Am Chem Soc. 2016 Mar 9;138(9):3022-30. doi: 10.1021/jacs.5b10491. Epub 2016 Feb 29.
The adsorptive separation of C2H2 and CO2 via porous materials is nontrivial due to the close similarities of their boiling points and kinetic diameters. In this work, we describe a new flexible porous coordination polymer (PCP) [Mn(bdc)(dpe)] (H2bdc = 1,4-benzenedicarboxylic acid, dpe = 1,2-di(4-pyridyl)ethylene) having zero-dimensional pores, which shows an adsorbate discriminatory gate effect. The compound shows gate opening type abrupt adsorption for C2H2 but not for CO2, leading to an appreciable selective adsorption of CO2 over C2H2 at near ambient temperature (273 K). The origin of this unique selectivity, as unveiled by in situ adsorption-X-ray diffraction experiments and density functional theory calculations, is due to vastly different orientations between the phenylene ring of bdc and each gas in the nanopores. The structural change by photochemical transformation of this PCP via [2 + 2] photodimerization leads to the removal of inverse CO2/C2H2 selectivity, verifying the mechanism of the guest discriminatory gate effect.
由于 C2H2 和 CO2 的沸点和动力学直径非常接近，因此通过多孔材料对它们进行吸附分离并非易事。在这项工作中，我们描述了一种新的柔性多孔配位聚合物（PCP）[Mn(bdc)(dpe)]（H2bdc=1,4-苯二甲酸，dpe=1,2-双（4-吡啶基）乙烯），具有零维孔，表现出吸附物区分性门效应。该化合物对 C2H2 表现出开笼型突然吸附，但对 CO2 没有，导致在接近环境温度（273 K）下对 CO2 具有可观的选择性吸附。通过原位吸附 X 射线衍射实验和密度泛函理论计算揭示了这种独特选择性的起源，这是由于苯环的不同取向bdc 和每个气体在纳米孔中。通过[2 + 2]光二聚化的光化学转化导致这种 PCP 的结构变化，从而去除了相反的 CO2/C2H2 选择性，验证了客体区分性门效应的机制。
