Microcalorimetric titration of a tetra-p-sulfonated calix[4]arene with alkylammonium ions in aqueous solution
作者:M. Stödeman、N. Dhar
DOI:10.1039/a708413g
日期:——
23-tetrasulfonate (CATS) consists of four para-sulfonated phenolic rings, which are connected via methylene groups in the meta-positions to a circular system. CATS was titrated with alkylammonium ions, H(CH2)nNH3+, n=3–7, in aqueous solution containing 0.01 mol l−1 phosphate buffer at pH 7.1. At this pH CATS carries five negative charges, one of its hydroxy groups and the four sulfonate groups are deprotonated
25,26,27,28-四羟基杯[4]芳烃-5,11,17,23-四磺酸盐(CATS)由四个对磺化酚环组成,它们通过亚甲基在间位连接到环状系统。在含有0.01 mol l -1的水溶液中,用烷基铵离子H(CH 2)n NH 3 +,n = 3-7滴定CATSpH 7.1的磷酸盐缓冲液。在此pH值下,CATS带有五个负电荷,其羟基之一和四个磺酸盐基团均被去质子化。使用等温导热微热量计在288.15、298.15和308.15 K下进行测量。假设为1:1结合模型,则将滴定曲线拟合为浓度结合常数K c和焓变ΔH °。从这些参数,Δ值ģ °,Δ小号°和Δ Ç p °,而得。作为涉及非极性表面脱水的相互作用的典型代表,温度依赖于ΔH °和ΔS°相互补偿,从而产生基本上温度不变的ΔG °。典型也是大和负Δ Ç p °具有铵离子的烷烃链长度的线性相关值。