High lipophilicity of perfluoroalkyl carboxylate and sulfonate: implications for their membrane permeability.
High lipophilicity of perfluoroalkyl carboxylate and sulfonate: implications for their membrane permeability.
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DOI：
10.1021/ja807961s
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发表时间：
2009-02-18
影响因子：
15
通讯作者：
Amemiya S
中科院分区：
文献类型：
--
作者：
Jing P;Rodgers PJ;Amemiya S
在这里，我们报告了全氟烷基羧酸盐和磺酸盐极高的亲油性。这类新兴有机污染物的亲油性被认为是其生物积累和毒性的来源。然而，羧酸盐和磺酸盐都被认为是亲水性的，而全氟烷基不仅是疏水的，而且是憎油的。用离子转移循环伏安法测定了全氟烷基和烷基羧酸盐同系物在水和正辛醇中的分配系数，以此来衡量它们的亲油性。通过对分配系数的片断分析，首次从实验上证明了相同长度的全氟烷基链和烷基链具有非常相似的亲油性。这一发现对全氟烷基化合物的制药和生物医学应用具有重要意义。有趣的是，全氟烷基羧酸盐或磺酸盐的亲油性比其烷基化合物高2个数量级，几乎完全归因于它们的氧阴离子基团。较高的亲油性源于全氟烷基对邻位氧阴离子的强吸电子作用，弱水合作用使其亲水性降低。事实上，对于全氟己基和羧酸基之间带有乙烯间隔物的氟调聚体来说，诱导效应大大降低，它的亲油性仅与其烷基对应物--壬酸酯相同，而亲油性则比全氟农酸盐低400倍。全氟烷基羧酸盐和磺酸盐的高亲油性表明，它们在膜/水界面的转移限制了它们对像双层脂膜这样薄的脂膜的渗透。与经典的溶解度-扩散模型中假设的膜内扩散控制的渗透率相比，极限渗透率更低，对亲脂性的依赖性也更小。
Here we report on remarkably high lipophilicity of perfluoroalkyl carboxylate and sulfonate. A lipophilic nature of this emerging class of organic pollutants has been hypothesized as an origin of their bioaccumulation and toxicity. Both carboxylate and sulfonate, however, are considered hydrophilic while perfluroalkyl groups are not only hydrophobic but also oleophobic. Partition coefficients of homologous series of perfluoroalkyl and alkyl carboxylates between water and n-octanol were determined as a measure of their lipophilicity by ion-transfer cyclic voltammetry. Very similar lipophilicity of perfluoroalkyl and alkyl chains with the same length is demonstrated experimentally for the first time by fragment analysis of the partition coefficients. This finding is important for pharmaceutical and biomedical applications of perfluoroalkyl compounds. Interestingly, ∼2 orders of magnitude higher lipophilicity of a perfluoroalkyl carboxylate or sulfonate in comparison to its alkyl counterpart is ascribed nearly exclusively to their oxoanion groups. The higher lipophilicity originates from a strong electron-withdrawing effect of the perfluoroalkyl group on the adjacent oxoanion group, which is weakly hydrated to decrease its hydrophilicity. In fact, the inductive effect is dramatically reduced for a fluorotelomer with an ethylene spacer between perfluorohexyl and carboxylate groups, which is only as lipophilic as its alkyl counterpart, nonanoate, and is 400 times less lipophilic than perfluorononanoate. The high lipophilicity of perfluoroalkyl carboxylate and sulfonate implies that their permeation across such a thin lipophilic membrane as a bilayer lipid membrane is limited by their transfer at a membrane/water interface. The limiting permeability is lower and less dependent on their lipophilicity than the permeability controlled by their diffusion in the membrane interior as assumed in the classical solubility-diffusion model.
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影响因子：
3
作者：
Ichieda, N;Shirai, O;Kihara, S
通讯作者：
Kihara, S
影响因子：
3.2
作者：
Fernandez Freire, P.;Martin, J. M. Perez;Hazen, M. J.
通讯作者：
Hazen, M. J.
影响因子：
3.4
作者：
FLEWELLING, RF;HUBBELL, WL
通讯作者：
HUBBELL, WL
影响因子：
11.4
作者：
Goss, Kai-Uwe;Bronner, Guido;Schmidt, Torsten C.
通讯作者：
Schmidt, Torsten C.
影响因子：
3.6
作者：
BRACE, NO
通讯作者：
BRACE, NO