Isotope Effects on Hydrogen Bonding and CH/CD-π Interaction
Isotope Effects on Hydrogen Bonding and CH/CD-π Interaction
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DOI：
10.1021/acs.jpcc.8b04144
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发表时间：
2018-07-05
影响因子：
3.7
通讯作者：
Otsuka, Koji
中科院分区：
文献类型：
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作者：
Kanao, Eisuke;Kubo, Takuya;Otsuka, Koji
我们用反相和正相条件下不同分离介质的液色谱(LC)，以质子化和/或氢化化合物为溶质，研究了同位素效应。反相色谱(RPLC)结果表明，由于同位素效应，同位素氢原子与流动相中羟基之间的氢键作用，使质子化化合物的疏水性明显增强。氢键的重要性也通过在正常相LC(NPLC)上用硅胶固定相分离同位素聚合物来支持，在NPLC上，氚化合物与硅醇上的羟基显示出更强的氢键。此外，我们还研究了CH-pi和Cd-pi相互作用强度的差异。用RPLC对同位素的自由能进行比较，结果表明CH-pi相互作用略强于Cd-pi相互作用。最后，我们用涂有C-70-富勒烯的柱，通过有效的CH/Cd-pi相互作用，展示了在NPLC上分离少数同位素的方法。
We study the isotope effect by liquid chromatography (LC) with a variety of separation media under reversed and normal phase conditions using the protiated and/or deuterated compounds as the solutes. Results of reversed phase LC (RPLC) suggested that the protiated compounds were more hydrophobic than that of deuterated compounds due to the isotope effect based on the hydrogen bonding between hydrogen atoms of isotopologues and hydroxy groups in the mobile phase. The importance of the hydrogen bonding was also supported by the separation of isotopologues with a silica stationary phase on normal phase LC (NPLC), where the deuterated compounds showed stronger hydrogen bonding to hydroxy groups on silanol. Additionally, we investigated the difference of the strength between CH-pi and CD-pi interactions. Comparison of free energies of isotopologues by RPLC suggested that the CH -pi interaction was slightly stronger than CD-pi interaction. Finally, we demonstrated the separation of a few isotopologues on NPLC using a column coated with C-70-fullerene, which is capable of strong pi-based interactions, by effective CH/CD-pi interactions.