Elucidating Cooperative Interactions between Grafted Amines and Tin or Titanium Sites on Silica
Elucidating Cooperative Interactions between Grafted Amines and Tin or Titanium Sites on Silica
复制标题
DOI：
10.1021/acscatal.2c02276
复制
发表时间：
2022-07
期刊：
影响因子：
12.9
通讯作者：
Christine Khoury;S. Holton;Dina Shpasser;Elior Hallo;A. Kulkarni;F. Jentoft;Oz M. Gazit
中科院分区：
文献类型：
--
作者：
Christine Khoury;S. Holton;Dina Shpasser;Elior Hallo;A. Kulkarni;F. Jentoft;Oz M. Gazit
有效促进固体表面上的协同催化相互作用对于一系列重要反应可以是非常有益的。在此，我们证明了二氧化硅上的孤立锡（Sn）和钛（Ti）位点与接枝伯胺（NH 2）的协同相互作用可以通过改变金属位点（M）的直接化学环境来调节。我们表明，通过拴系各种大小的有机配体（RO）的M网站，我们可以管理的网站之间的相互作用，测量的存在下NH3+。我们发现，NH 3+的浓度与模型亨利反应的活性直接相关。我们进一步发现，烯烃产物的选择性从59%的接枝NH 2和表面硅烷醇的协同相互作用提高到84-92%的接枝NH 2和孤立的Sn或Ti位点之间的协同相互作用。通过DFT的分析表明，这些合作的相互作用，使通过存在的痕量（每M站点两个分子）的水附近的金属网站和由此产生的水解，这取决于RO基团的疏水性和金属的性质。因此，目前的工作提供了先进的分子水平的见解，固体表面上的合作相互作用的基本原则和指导，通过调整化学环境来管理这种相互作用。
The efficient promotion of cooperative catalytic interactions on solid surfaces can be of great benefit for a range of important reactions. Herein, we demonstrate that the cooperative interactions of isolated tin (Sn) and titanium (Ti) sites on silica with grafted primary amines (NH2) can be tuned by changing the immediate chemical environment of the metal sites (M). We show that, by tethering various size organic ligands (RO) to the M sites, we can govern the interactions between the sites as measured by the presence of NH3+. We show that the concentration of NH3+is directly correlated with the activity of the model Henry reaction. We further find that the selectivity to the olefinic product increased from 59% for the cooperative interactions of grafted NH2and surface silanols to 84–92% for the cooperative interactions between grafted NH2and the isolated Sn or Ti sites. An analysis by DFT shows that these cooperative interactions are enabled by the presence of a trace amount (two molecules per M site) of water near the metal sites and a resulting hydrolysis, which depends on the hydrophobicity of the RO group and the nature of the metal. Hence, the current work provides advanced molecular-level insights into the underlying principles of cooperative interactions on a solid surface and guidance for governing such interactions by tuning the chemical environment.