Francisco Vitor, Basílio Nuno, García-Río Luis
Departamento de Química Física, Centro de Investigación en Química Biológica y Materiales Moleculares (CIQUS), Universidad de Santiago de Compostela , 15782 Santiago de Compostela, Spain.
J Phys Chem B. 2014 May 1;118(17):4710-6. doi: 10.1021/jp502097q. Epub 2014 Apr 22.
The effect of alkali and transition metal cations in the formation of host-guest complexes with the water-soluble p-sulfonatocalix[4]arene (SC4) was studied using 2-chloropyridine and Na(+) and Cu(2+) as model guest and model cations, respectively. The results obtained from isothermal titration calorimetry and NMR experiments provide evidence for the formation of 1:1:1 ternary complexes for both cations with Cu(2+) showing positive cooperativity and Na(+) negative cooperativity. The formation of ternary complexes comprising transition metal cations has been scarcely explored but present high potential for devising catalytic systems/models or for enhancing the stability and selectivity of SC4 complexes. Because transition metal cations are usually present in solution together with other SC4 countercations (e.g., Na(+)), a general binding model that considers the dynamic formation of all possible complexes (including ionic exchange between ternary complexes) is presented. This model allows the optimization of the conditions required to selectively form target complexes.
以2-氯吡啶、Na⁺和Cu²⁺分别作为模型客体和模型阳离子，研究了碱金属和过渡金属阳离子在与水溶性对磺酸基杯[4]芳烃（SC4）形成主客体配合物中的作用。等温滴定量热法和核磁共振实验结果证明，两种阳离子均形成了1:1:1的三元配合物，其中Cu²⁺表现出正协同效应，Na⁺表现出负协同效应。包含过渡金属阳离子的三元配合物的形成鲜有研究，但在设计催化体系/模型或提高SC4配合物的稳定性和选择性方面具有很大潜力。由于过渡金属阳离子通常与其他SC4抗衡阳离子（如Na⁺）一起存在于溶液中，因此提出了一个考虑所有可能配合物动态形成（包括三元配合物之间的离子交换）的通用结合模型。该模型有助于优化选择性形成目标配合物所需的条件。
