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首页> 外文期刊>Journal of the American Chemical Society >Structural Characterization of Protonated Water Clusters Confined in HZSM-5 Zeolites
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Structural Characterization of Protonated Water Clusters Confined in HZSM-5 Zeolites

机译：HZSM-5沸石局限于质子化水簇的结构表征

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摘要

A molecular description of the structure and behavior of water confined in aluminosilicate zeolite pores is a crucial component for understanding zeolite acid chemistry under hydrous conditions. In this study, we use a combination of ultrafast two-dimensional infrared (2D IR) spectroscopy and ab initio molecular dynamics (AIMD) to study H_2O confined in the pores of highly hydrated zeolite HZSM-5 (～13 and ～6 equivalents of H_2O per Al atom). The 2D IR spectrum reveals correlations between the vibrations of both terminal and H-bonded O-H groups and the continuum absorption of the excess proton. These data are used to characterize the hydrogen-bonding network within the cluster by quantifying single-, double-, and non-hydrogen-bond donor water molecules. These results are found to be in good agreement with the statistics calculated from an AIMD simulation of an H~+(H_2O)_8 cluster in HZSM-5. Furthermore, IR spectral assignments to local O-H environments are validated with DFT calculations on clusters drawn from AIMD simulations. The simulations reveal that the excess charge is detached from the zeolite and resides near the more highly coordinated water molecules in the cluster. When they are taken together, these results unambiguously assign the complex IR spectrum of highly hydrated HZSM-5, providing quantitative information on the molecular environments and hydrogen-bonding topology of protonated water clusters under extreme confinement.
机译：在硅铝晶沸石孔中限制的水的结构和行为的分子描述是在含水条件下了解沸石酸化学的关键组分。在这项研究中，我们使用超快二维红外（2D IR）光谱和AB Initio分子动力学（AIMD）的组合研究H_2O限制在高度水合沸石HZSM-5的孔中（〜13和〜6当量的H_2O每个Al原子）。 2D IR光谱揭示了末端和H键合O-H组的振动与过量质子的连续吸收之间的相关性。这些数据用于通过量化单，双和非氢键供体水分子来表征簇内的氢键网络。这些结果与HZSM-5中的H〜+（H_2O）_8集群的AIMD模拟计算的统计数据吻合良好。此外，对本地O-H环境的IR光谱分配用来自AIMD仿真绘制的群集的DFT计算验证。仿真揭示了多余的电荷从沸石中脱离，并且驻留在簇中更高度协调的水分子附近。当它们被占用时，这些结果明确地分配了高度水合HZSM-5的复杂IR光谱，在极端限制下提供了关于质子化水簇的分子环境和氢键拓扑的定量信息。

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  • 来源
    《Journal of the American Chemical Society》 |2021年第27期|10203-10213|共11页
  • 作者

    John H. Hack; James P. Dombrowski; Xinyou Ma; Yaxin Chen; Nicholas H. C. Lewis; William B. Carpenter; Chenghan Li; Gregory A. Voth; Harold H. Kung; Andrei Tokmakoff;

  • 作者单位

    Department of Chemistry James Franck Institute and Institute for Biophysical Dynamics The University of Chicago Chicago Illinois 60637 United States;

    Department of Chemical and Biological Engineering Northwestern University Evanston Ilinois 60208-3120 United States;

    Department of Chemistry James Franck Institute and Institute for Biophysical Dynamics and Chicago Center for Theoretical Chemistry The University of Chicago Chicago Illinois 60637 United States;

    Department of Chemical and Biological Engineering Northwestern University Evanston Ilinois 60208-3120 United States;

    Department of Chemistry James Franck Institute and Institute for Biophysical Dynamics The University of Chicago Chicago Illinois 60637 United States;

    Department of Chemistry James Franck Institute and Institute for Biophysical Dynamics The University of Chicago Chicago Illinois 60637 United States;

    Department of Chemistry James Franck Institute and Institute for Biophysical Dynamics and Chicago Center for Theoretical Chemistry The University of Chicago Chicago Illinois 60637 United States;

    Department of Chemistry James Franck Institute and Institute for Biophysical Dynamics and Chicago Center for Theoretical Chemistry The University of Chicago Chicago Illinois 60637 United States;

    Department of Chemical and Biological Engineering Northwestern University Evanston Ilinois 60208-3120 United States;

    Department of Chemistry James Franck Institute and Institute for Biophysical Dynamics The University of Chicago Chicago Illinois 60637 United States;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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