The inclusion complexation behavior of the dye guest molecule neutral red with three kinds of water-soluble p-sulfonated calix[n]arene sodium (n=4,6,8) was investigated. p-Sulfonated calix[4,6,8]arene sodium (pSC4, pSC6, pSC8) can react with neutral red to form inclusion complexes, which were confirmed by UV-vis absorption and fluorescence spectroscopy. Fluorescence spectroscopy experiments were performed in pH=4.6 acetic buffer solutions at 25 °C to calculate the stability constants (K S) for the stoichiometric 1:1 inclusion complexes of pSC4, pSC6 and pSC8 with neutral red. The thermodynamic parameters for the inclusion complexes were determined through a van’t Hoff analysis. Formation of the inclusion complexes of pSC4, pSC6 and pSC8 with neutral red was driven by favorable enthalpic changes with their accompanying negative entropy changes. The complex stability constants monotonically increased with the number of phenolic units in the calixarene ring, which was attributed mainly to electrostatic interactions and hydrogen bonding, rather than to the cavity size.
研究了
染料客体分子
中性红与三种
水溶性对磺化
钙[n]炔
钠(n=4,6,8)的包合络合行为。对磺化
钙[4,6,8]炔
钠(pSC4, pSC6, pSC8)能与
中性红反应形成包合络合物,并通过紫外-可见吸收和荧光光谱证实了这一点。荧光光谱实验是在 25 °C、pH=4.6 的
乙酸缓冲溶液中进行的,目的是计算 pSC4、pSC6 和 pSC8 与
中性红按 1:1 的比例形成的包合物的稳定常数(K S)。包合物的热力学参数是通过范特霍夫分析确定的。pSC4、pSC6 和 pSC8 与
中性红的包合复合物的形成是由有利的焓变和伴随的负熵变驱动的。络合物的稳定性常数随萼烯环中
酚类单元数量的增加而单调增加,这主要归因于静电相互作用和氢键,而非空腔大小。