连接基取代基性质对 UiO-66 活性位点性能的影响：FT-IR 和 DFT 组合研究,International Journal of Molecular Sciences

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连接基取代基性质对 UiO-66 活性位点性能的影响：FT-IR 和 DFT 组合研究
International Journal of Molecular Sciences ( IF 4.9 ) Pub Date : 2023-10-04 , DOI: 10.3390/ijms241914893
Viktoriia V Torbina ₁ , Mikhail A Salaev ₁ , Evgeniy A Paukshtis ₂ , Leonarda F Liotta ₃ , Olga V Vodyankina ₁

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有机连接取代基的性质在气体吸附和分离以及金属有机骨架的催化应用中起着重要作用。锆基 UiO-66 是此类材料中可调性最强的成员之一。然而，对其性质的预测仍然不是一个完全解决的问题。在这里，使用高灵敏度 CO 探针分子的红外光谱测量，结合 DFT 计算，用于表征由于不同有机连接取代基的存在而引起的不同酸性位点的性能。所提出的模型可以区分 UiO-66 上的各个活性位点并澄清它们的行为。与 CO 吸附相关的实验红外谱带可以明确地分配给一种类型的位点或另一种类型的位点。先前未描述的高度红移带归因于CO通过O原子吸附在配位不饱和锆位点上。结果证实，当对苯二甲酸酯部分中分别包含吸电子基团和给电子基团时，UiO-66 结构中连接子缺陷上配位不饱和 Zr 位点的路易斯酸度较低和较高，而锆氧代的布朗斯台德酸度则较高。集群几乎保持不变。

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Effect of Linker Substituent Nature on Performance of Active Sites in UiO-66: Combined FT-IR and DFT Study

The nature of organic linker substituents plays an important role in gas sorption and separation as well as in catalytic applications of metal–organic frameworks. Zirconium-based UiO-66 is one of the most tunable members of this class of materials. However, the prediction of its properties is still not a fully solved problem. Here, the infrared spectroscopic measurements using highly sensitive CO probe molecules, combined with DFT calculations, are used in order to characterize the performance of different acidic sites caused by the presence of different organic linker substituents. The proposed model allowed differentiation between various active sites over the UiO-66 and clarification of their behavior. The experimental IR bands related to CO adsorption can be unambiguously assigned to one type of site or another. The previously undescribed highly red-shifted band is attributed to CO adsorbed on coordinatively unsaturated zirconium sites through an O atom. The results confirm the lower and higher Lewis’s acidity of coordinatively unsaturated Zr sites on linker defects in the UiO-66 structure when electron-withdrawing and electron-donating groups are, respectively, included in a terephthalate moiety, whilst the Brønsted acidity of zirconium oxo-cluster remains almost unchanged.

更新日期：2023-10-05

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