Predicting the Conformation of Organic Catalysts Grafted on Silica Surfaces with Different Numbers of Tethering Chains: The Silicopodality Concept,The Journal of Physical Chemistry C

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Predicting the Conformation of Organic Catalysts Grafted on Silica Surfaces with Different Numbers of Tethering Chains: The Silicopodality Concept
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2021-09-17 , DOI: 10.1021/acs.jpcc.1c06150
Ivana Miletto ₁ , Chiara Ivaldi ₁ , Enrica Gianotti ₁ , Geo Paul ₁ , Fabio Travagin ₂ , Giovanni Battista Giovenzana _{2,

3} , Alberto Fraccarollo ₁ , Davide Marchi ₁ , Leonardo Marchese ₁ , Maurizio Cossi ₁

Affiliation

Hybrid catalysts are attracting much attention, since they combine the versatility and efficiency of homogeneous organic catalysis with the robustness and thermal stability of solid materials, for example, mesoporous silica; in addition, they can be used in cascade reactions, for exploring both organic and inorganic catalysis at the same time. Despite the importance of the organic/inorganic interface in these materials, the effect of the grafting architecture on the final conformation of the organic layer (and hence its reactivity) is still largely unexplored. Here, we investigate a series of organosiloxanes comprising a pyridine ring (the catalyst model) and different numbers of alkylsiloxane chains used to anchor it to the MCM-41 surface. The hybrid interfaces are characterized with X-ray powder diffraction, thermogravimetric analyses, Fourier-transform infrared spectroscopy, nuclear magnetic resonance techniques and are modeled theoretically through molecular dynamics (MD) simulations, to determine the relationship between the number of chains and the average position of the pyridine group; MD simulations also provide some insights about temperature and solvent effects.

中文翻译：

预测接枝在具有不同数量束缚链的二氧化硅表面上的有机催化剂的构象：硅足性概念

混合催化剂备受关注，因为它们结合了均相有机催化的多功能性和效率以及固体材料（例如介孔二氧化硅）的坚固性和热稳定性；此外，它们还可用于级联反应，同时探索有机和无机催化作用。尽管有机/无机界面在这些材料中很重要，但接枝结构对有机层最终构象（及其反应性）的影响仍然很大程度上未被探索。在这里，我们研究了一系列包含吡啶环（催化剂模型）和不同数量的烷基硅氧烷链的有机硅氧烷，用于将其锚定到 MCM-41 表面。通过 X 射线粉末衍射、热重分析、傅里叶变换红外光谱、核磁共振技术对混合界面进行表征，并通过分子动力学 (MD) 模拟进行理论建模，以确定链数与平均位置之间的关系吡啶基团的； MD 模拟还提供了一些关于温度和溶剂影响的见解。

更新日期：2021-09-30

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