Salazar J M, Weber G, Simon J M, Bezverkhyy I, Bellat J P
Laboratoire Interdisciplinaire Carnot de Bourgogne, Adsorption Sur Solides Poreux (ASP), UMR-6303 CNRS-Université de Bourgogne, 9, Av. Alain Savary B.P. 47870 F-21078 Dijon Cedex, France.
J Chem Phys. 2015 Mar 28;142(12):124702. doi: 10.1063/1.4914903.
Here, we report ab-initio calculations developed with a twofold purpose: understand how adsorbed water molecules alter the infrared spectrum of the metal-organic framework MIL-53(Al) and to investigate which are the associated physico-chemical processes. The analyzed structures are the two anhydrous narrow (np⊘) and large (lp⊘) pore forms and the hydrated narrow pore form (np-H2O) of the MIL-53(Al). For these structures, we determined their corresponding infrared spectra (FTIR) and we identified the vibrational modes associated to the dominant spectral lines. We show that wagging and scissoring modes of CO2 give flexibility to the structure for facilitating the lp⊘- np⊘ transition. In our studies, this transition is identified by eight vibrational modes including the δCH(18a) vibrational mode currently used to identify the mentioned transition. We report an exhaustive band identification of the infrared spectra associated to the analyzed structures. Moreover, the FTIR for the np-H2O structure allowed us to identify four types of water molecules linked to the host structure by one to three hydrogen bonds.
在此，我们报告了基于两个目的进行的从头算计算：一是了解吸附的水分子如何改变金属有机骨架MIL-53(Al)的红外光谱，二是研究相关的物理化学过程。所分析的结构是MIL-53(Al)的两种无水窄孔（np⊘）和大孔（lp⊘）形式以及水合窄孔形式（np-H2O）。对于这些结构，我们确定了它们相应的红外光谱（FTIR），并识别了与主要谱线相关的振动模式。我们表明，CO2的摇摆和剪式模式赋予结构灵活性，以促进lp⊘-np⊘转变。在我们的研究中，这种转变由八种振动模式识别，包括目前用于识别上述转变的δCH(18a)振动模式。我们报告了与所分析结构相关的红外光谱的详尽谱带识别。此外，np-H2O结构的FTIR使我们能够识别通过一到三个氢键与主体结构相连的四种类型的水分子。
