Investigation of the upper rim binding of triphenylpyrylium cation with p-sulfonatocalix[4]arene

The interaction of 2,4,6-triphenylpyrylium cation with p-sulfonatocalix[4]arene is studied using absorption, emission, NMR and electrochemical techniques. The increase in the absorption is observed with the increase in the concentration of p-sulfonatocalix[4]arene. The emission intensity of 2,4,6-triphenylpyrylium cation is also enhanced in the presence of p-sulfonatocalix[4]arene. The electrochemical titration reveals the presence of host–guest interaction. The NMR analysis explains the upper rim interaction of 2,4,6-triphenypyrylium cation with p-sulfonatocalix[4]arene. The mode of binding is studied using computational methods. The quantum chemical simulations reveal the binding orientation of cationic TPP with p-SC4. The calculated complexation energy (− 33.19 kcal mol−1) indicates the strong binding nature of 2,4,6-triphenylpyrylium cation with p-sulfonatocalix[4]arene.

本研究采用吸收光谱、发射光谱、核磁共振波谱（NMR）及电化学技术，对2,4,6-三苯基吡喃鎓阳离子与对磺酰基杯[4]芳烃（p-sulfonatocalix[4]arene）之间的相互作用展开了探究。随着对磺酰基杯[4]芳烃浓度升高，体系的吸收信号强度随之增强；2,4,6-三苯基吡喃鎓阳离子的发射光强度在对磺酰基杯[4]芳烃存在时同样得到提升。电化学滴定实验证实了二者间存在主客体相互作用，核磁共振波谱分析表明，2,4,6-三苯基吡喃鎓阳离子与对磺酰基杯[4]芳烃的结合位点位于杯芳烃的上沿。本研究通过计算方法对二者的结合模式进行了探究，量子化学模拟揭示了阳离子型TPP与p-SC4的结合取向，计算得到的络合能为−33.19 kcal·mol⁻¹，表明2,4,6-三苯基吡喃鎓阳离子与对磺酰基杯[4]芳烃之间具有较强的结合能力。