β-环糊精与十四烷基硫酸钠和全氟辛酸钠等摩尔混合体系的相互作用

Interactions between β-Cyclodextrin and the Equimolar Mixture of Sodium Tetradecyl Sulfate and Sodium Perfluorooctanoate

通过1HNMR和19FNMR相结合的方法研究了十四烷基硫酸钠(C14H29SO4Na,STS)和全氟辛酸钠(C7F15COONa,SPFO)等摩尔混合体系与β-环糊精(β-CD)的相互作用.实验发现,尽管STS的临界胶束浓度(cmc)明显小于SPFO,即在水溶液中STS的疏水性要强于SPFO,但是β-CD仍首先选择性包结SPFO形成1∶1包结物,然后随β-CD浓度增加主要生成STS的1∶1包结物,最后STS的2∶1(β-CD/STS)包结物和SPFO的2∶1(β-CD/SPFO)包结物同时生成.结合我们以前的工作,本文表明,随着碳氢表面活性剂烷基硫酸钠的链长(8～12)进一步增加到14,β-CD对氟表面活性剂SPFO的选择性进一步减弱.也就是说,由于β-CD的空腔和碳氟链更加匹配以及碳氟链的刚性使得β-CD/SPFO包结物的形成始终更为有利,但这两类表面活性剂疏水性的差别对于这种选择性的程度会产生一定影响.

The interactions between β-cyclodextrin （β-CD） and the equimolar mixture of sodium tetradecyl sulfate （STS） and sodium perfluorooctanoate （SPFO） were studied by ^1H and ^19F NMR. The results showed that β-CD selectively included SPFO to form 1 ： 1 complexes even though the cmc of STS was remarkably smaller than that of SPFO, i.e. STS was more hydrophobic than SPFO. With the further increase of β-CD concentration, the 1 ： 1 β-CD/STS complexes were then significantly formed until both 2 ： 1 complexes of β-CD/STS and β-CD/SPFO were formed simultaneously. As a complement of our previous work, it was noted that when the chain length of sodium alkyl sulfates （C8～C12） was further increased to C14, the extent of selectivity of β-CD to SPFO was further decreased. In other words, SPFO still showed advantage of competition for β-CD to form inclusion complexes due to its rigidity and the better fit to the cavity of β-CD, however, the hydrophobicity of STS showed stronger influence on such selectivity than that of C8～C12.