Quantitative Kinetic Modeling in Photoresponsive Supramolecular Chemistry: The Case of Water-Soluble Azobenzene/Cyclodextrin Complexes

Hydrophilic host–guest complexes, consisting of water-soluble azobenzene and α-, β-, or γ-cyclodextrins, have been proposed as a model to study supramolecular photoresponsive systems in aqueous environments through a full spectrometric approach combined with a simulation and data fitting methodology. Various essential and complementary spectroscopic techniques have been used: circular dichroism to determine whether the complex is formed or not, NMR for the stoichiometry elucidation, and UV–visible spectrophotometry to obtain the association equilibrium constant of each complex and the quantum yield for each photochemical process. A step-by-step fitting procedure is presented, which enables the determination of all thermodynamic and photokinetic parameters. A sequential methodology is applied to dissipate all uncertainties on the variability of the results and to develop a relevant and reliable protocol applicable to other types of complexes. The proposed procedure has thus been shown to be very robust and largely applicable to other photoresponsive host–guest systems.

以水溶性偶氮苯与α、β或γ-环糊精构建的亲水主客体复合物（hydrophilic host–guest complexes），被提出作为模型体系，用于通过结合模拟与数据拟合方法的全光谱学表征手段，研究水环境中的超分子光响应体系。本研究采用了多种不可或缺且互为补充的光谱表征技术：利用圆二色谱（circular dichroism）判别复合物是否成功形成，借助核磁共振波谱法（Nuclear Magnetic Resonance，简称NMR）明确复合物的结合计量比，并通过紫外-可见分光光度法（ultraviolet-visible spectrophotometry）获取各复合物的结合平衡常数以及各光化学过程的量子产率。本文提出了一套分步拟合流程，可精准确定所有热力学与光动力学参数。同时采用序贯分析方法消除结果变异性带来的全部不确定性，并开发出一套可推广至其他类型复合物的普适可靠实验方案。研究证实，所提出的流程具备极佳的鲁棒性，可广泛适配各类其他光响应主客体体系。