Pessêgo Márcia, Da Silva José P, Moreira José A, García-Río Luis
Departamento de Química Física, Centro de Investigación en Química Biológica y Materiales Moleculares (CIQUS), Universidad de Santiago, 15782 Santiago (Spain).
CIQA, Departamento de Química e Farmácia, Faculdade de Ciências e Tecnologia, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro (Portugal).
Chempluschem. 2013 Sep;78(9):1058-1064. doi: 10.1002/cplu.201300164. Epub 2013 Jul 4.
The formation of host/guest complexes between cucurbit[7]uril (CB7) and tetradecyltrialkylammonium bromide surfactants with trimethyl (C TMA ), triethyl (C TEA ), and tripropyl (C TPA ) head groups was studied. Complexation was studied by ESI-MS, isothermal titration calorimetry (ITC), and NMR spectroscopy. The structure of the complexes is strongly dependent on the surfactant head group. Both 1:1 and 2:1 complexes are formed with all cationic surfactants. The magnitude of the K binding constants decreases with the alkyl length of the head group, whereas that of the K binding constants is independent of the nature of the surfactant head group. Distinct structures were found for the 1:1 and 2:1 complexes. C TMA and C TPA surfactants form 1:1 inclusion complexes that comprise the head group close to the CB7 portal and 2:1 external complexes with both host molecules near the head group. The 1:1 complexes between C TEA and CB7 showed that the head group was centered inside the CB7 cavity, whereas in the 2:1 complex the second molecule of CB7 was located at the end of the main alkyl chain.
研究了葫芦[7]脲（CB7）与具有三甲基（CTMA）、三乙基（CTEA）和三丙基（CTPA）头部基团的十四烷基三烷基溴化铵表面活性剂之间主客体配合物的形成。通过电喷雾电离质谱（ESI-MS）、等温滴定量热法（ITC）和核磁共振光谱法（NMR）研究了络合作用。配合物的结构强烈依赖于表面活性剂的头部基团。所有阳离子表面活性剂均形成1:1和2:1的配合物。结合常数K的大小随着头部基团烷基长度的增加而减小，而结合常数K与表面活性剂头部基团的性质无关。1:1和2:1配合物具有不同的结构。CTMA和CTPA表面活性剂形成1:1包合物，其头部基团靠近CB'7入口，以及2:1外部配合物，两个主体分子靠近头部基团。CTEA与CB7之间的1:1配合物表明，头部基团位于CB7腔的中心，而在2:1配合物中，第二个CB7分子位于主烷基链的末端。
