Dines Trevor J, MacGregor Louise D, Rochester Colin H
Division of Physical and Inorganic Chemistry, Carnelley Building, University of Dundee, Dundee DD1 4HN, UK.
Spectrochim Acta A Mol Biomol Spectrosc. 2003 Nov;59(13):3205-17. doi: 10.1016/s1386-1425(03)00139-2.
The adsorption of 2-chloropyridine on SiO(2), TiO(2), ZrO(2), SiO(2)-Al(2)O(3) and H-mordenite has been studied by IR spectroscopy. The different modes of interaction with oxide surfaces, i.e. hydrogen-bonding and adsorption at Brønsted or Lewis acid sites, was modelled by ab initio calculations at the B3LYP/DZ+(d) level. Adsorption on SiO(2) results in hydrogen bonding to surface hydroxyl groups, whereas the spectra obtained following adsorption on TiO(2) and ZrO(2) display evidence for electron transfer at Lewis acidic surface sites. Protonation of 2-chloropyridine at Brønsted acidic sites was detected only for adsorption on SiO(2)-Al(2)O(3) and H-mordenite, indicating the presence of Brønsted acidic sites on these oxide surfaces with pK(a) values </=0.70. IR studies of 2-chloropyridine adsorption can provide useful information regarding the nature of surface acidity on oxides which is complementary to that obtained from other probe molecules such as NHs and pyridine.
通过红外光谱研究了2-氯吡啶在SiO₂、TiO₂、ZrO₂、SiO₂ -Al₂O₃和H-丝光沸石上的吸附情况。利用B3LYP/DZ+(d)水平的从头算计算对与氧化物表面的不同相互作用模式，即氢键以及在布朗斯台德或路易斯酸位点的吸附进行了模拟。在SiO₂上的吸附导致与表面羟基形成氢键，而在TiO₂和ZrO₂上吸附后获得的光谱显示出在路易斯酸性表面位点发生电子转移的证据。仅在SiO₂ -Al₂O₃和H-丝光沸石上的吸附中检测到2-氯吡啶在布朗斯台德酸性位点的质子化，这表明这些氧化物表面存在pKₐ值≤0.70的布朗斯台德酸性位点。2-氯吡啶吸附的红外研究可以提供有关氧化物表面酸性本质的有用信息，这与从其他探针分子（如NH₃和吡啶）获得的信息互为补充。
