Department of Chemistry, University of South Florida , 4202 East Fowler Avenue, CHE205, Tampa, Florida 33620-5250, United States.
Department of Chemical and Environmental Sciences, University of Limerick , Limerick, Republic of Ireland.
Langmuir. 2016 Nov 8;32(44):11492-11505. doi: 10.1021/acs.langmuir.6b03161. Epub 2016 Oct 24.
Molecular simulations of CO and H sorption were performed in MPM-1-Cl and MPM-1-TIFSIX, two robust molecular porous materials (MPMs) with the empirical formula [Cu(adenine)Cl]Cl and [Cu(adenine)(TiF)], respectively. Recent experimental studies have shown that MPM-1-TIFSIX displayed higher CO uptake and isosteric heat of adsorption (Q) than MPM-1-Cl [Nugent, P. S.; et al. J. Am. Chem. Soc. 2013, 135, 10950-10953]. This was verified through the simulations executed herein, as the presented simulated CO sorption isotherms and Q values are in very good agreement with the corresponding experimental data for both MPMs. We also report experimental H sorption data in both MPMs. Experimental studies revealed that MPM-1-TIFSIX exhibits high H uptake at low loadings and an initial H Q value of 9.1 kJ mol. This H Q value is greater than that for a number of existing metal-organic frameworks (MOFs) and represents the highest yet reported for a MPM. The remarkable H sorption properties for MPM-1-TIFSIX have been confirmed through our simulations. The modeling studies revealed that only one principal sorption site is present for CO and H in MPM-1-Cl, which is sorption onto the Cl counterions within the large channels. In contrast, three different sorption sites were discovered for both CO and H in MPM-1-TIFSIX: (1) between two TIFSIX groups within a small passage connecting the large channels, (2) onto the TIFSIX ions lining the large channels, and (3) within the small channels. This study illustrates the detailed insights that molecular simulations can provide on the CO and H sorption mechanism in MPMs.
采用分子模拟的方法研究了 CO 和 H 在两种结构稳定的多孔材料 MPM-1-Cl 和 MPM-1-TIFSIX 中的吸附行为，这两种材料的经验式分别为[Cu(腺嘌呤)Cl]Cl 和 [Cu(腺嘌呤)(TiF)]。最近的实验研究表明，MPM-1-TIFSIX 的 CO 吸附量和等吸附热(Q)高于 MPM-1-Cl [Nugent, P. S.; 等人. J. Am. Chem. Soc. 2013, 135, 10950-10953]。通过在此处执行的模拟，验证了这一结果，因为所呈现的模拟 CO 吸附等温线和 Q 值与两种 MPM 的相应实验数据非常吻合。我们还报道了这两种 MPM 中的实验 H 吸附数据。实验研究表明，MPM-1-TIFSIX 在低负荷下具有较高的 H 吸附量，初始 H Q 值为 9.1 kJ mol。该 H Q 值大于一些现有的金属有机骨架(MOFs)，代表了迄今为止报道的 MPM 中最高的值。通过我们的模拟，证实了 MPM-1-TIFSIX 具有出色的 H 吸附性能。模型研究表明，在 MPM-1-Cl 中，CO 和 H 只有一个主要的吸附位，即在大通道内的 Cl 反离子上的吸附。相比之下，在 MPM-1-TIFSIX 中，发现了 CO 和 H 的三个不同的吸附位：(1) 大通道之间的小通道中两个 TIFSIX 基团之间，(2) 大通道中的 TIFSIX 离子上，以及(3) 小通道内。这项研究说明了分子模拟可以为 MPM 中 CO 和 H 的吸附机制提供的详细见解。
