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采用荧光光谱和紫外光谱研究葫芦[6]脲(CB[6])与土霉素(OTC)的分子识别作用。实验结果表明,随着主体分子的加入,OTC荧光强度和紫外吸收强度均增强,说明主客体之间发生了相互作用;进一步通过荧光光谱、紫外光谱和直线拟合法(Benesi-Hildebrand)确定了CB[6]与OTC形成1∶1型的包结物;在酸性环境下CB[6]与OTC能形成1∶1型的稳定的包结物,在碱性环境下不能形成稳定的包结物;同时计算了主客体在298,308和328K下包结的平衡常数Ks和CB[6]与OTC的分子识别过程的熵变、焓变和吉布斯自由能变。不同温度下的吉布斯自由能变ΔG均小于0,而熵变和焓变为正值,其包结过程是疏水作用力驱动且自发的吸热的过程。
The molecular recognition of cucurbit [6] urea (CB [6]) and oxytetracycline (OTC) was studied by fluorescence and UV spectroscopy. The experimental results showed that with the addition of host molecules, the fluorescence intensity and UV absorption intensity of OTC increased, which indicated the interaction between host and guest. The interaction between host and guest was further confirmed by fluorescence spectroscopy, UV spectroscopy and linear fitting (Benesi-Hildebrand) [6] formed a 1: 1 inclusion with OTC; CB [6] and OTC formed a stable 1: 1 inclusion in an acidic environment and did not form a stable inclusion under alkaline conditions At the same time, the entropy change, enthalpy change and Gibbs free energy change of the equilibrium constants Ks and CB [6] for inclusion of host and guest at 298,308 and 328K and the molecular recognition process of OTC were calculated. The Gibbs free energy change ΔG under different temperatures is less than 0, while the entropy change and enthalpy change to positive values. The inclusion process is a spontaneous endothermic process driven by hydrophobic force.