Surfing silica surfaces superciliously.
Surfing silica surfaces superciliously.
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DOI：
10.1016/j.chroma.2004.05.073
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发表时间：
2004-10
期刊：
影响因子：
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通讯作者：
P. Righetti;C. Gelfi;R. Sebastiano;A. Citterio
中科院分区：
文献类型：
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作者：
P. Righetti;C. Gelfi;R. Sebastiano;A. Citterio
本小型审查总结了我们小组在开发不同类别的新型季铵化杂环化合物能够调制和逆转的电内渗流（EEP）在一个最奇特的方式收集的经验。第一类包括单盐化合物，其具有不同长度（通常为C4-C8）的决定簇ω-碘代烷基链，能够在碱性pH下被二氧化硅吸附，并自发地烷基化电离的硅烷醇，从而共价附着于其上。第二类由二盐化合物构成，其连接在可变长度（在此也通常为C4-C8）的烷基链的末端。这第二类是无法结合共价二氧化硅表面，虽然，在薄层色谱法，它表现出非凡的亲和力，二氧化硅珠，相反的第一个。的基础上的显着不同的行为，结构规则推导出的最低要求，一般类别的胺结合到二氧化硅的墙壁和修改的。对于不能共价结合到壁的化合物，最重要的结构基序是由C4链隔开的两个季氮：这似乎是平均距离（即，0.8nm），以用于紧密配合。另一个结构结合基序是“疏水装饰”，即，各种胺中带电基团与烷基残基的比率;具有高水平的这种烷烃基团的胺（即，具有更高的疏水性），似乎更牢固地结合到壁上，这可能是由于当覆盖二氧化硅时，胺衍生物本身之间的疏水相互作用而不是与壁的疏水相互作用。
The present mini-review summarizes the experience gathered by our group in developing different classes of novel quaternarized heterocyclic compounds able to modulate and reverse the electroendoosmotic flow (EOF) in a most peculiar manner. The first class comprises mono-salt compounds, with the determinant ω-iodoalkyl chains of different lengths (typically C4–C8), able to be adsorbed by silicas, at alkaline pH, and spontaneously alkylate ionised silanols, thus becoming covalently affixed to it. The second class is constituted by di-salt compounds, attached at the termini of an alkyl chain of variable lengths (here too, typically, C4–C8). This second class is unable to bind covalently silica surfaces, although, in thin-layer chromatography, it exhibits an extraordinary affinity for silica beads, contrary to the first one. On the basis of the strikingly different behaviour, structural rules are derived for the minimum requirements for general classes of amines to bind to silica walls and modify EOF. For compounds unable to bind covalently to the wall, the most important structural motif is two quaternary nitrogens spaced apart by a C4chain: this seems to be the average distance (i.e., 0.8nm) between two adjacent, ionized silanols for a snug fit. The other structural binding motif is the “hydrophobic decoration”, i.e., the ratio of charged groups to alkyl residue in the various amines; amines with high levels of such alkane groups (i.e., with higher hydrophobicity), seem to bind more tenaciously to the wall, probably due to hydrophobic interaction not to the wall but among the amine derivatives themselves, when carpeting the silica.