Influence of the Solvent on the Thermal Back Reaction of One Spiropyran
Influence of the Solvent on the Thermal Back Reaction of One Spiropyran
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DOI：
10.1021/ed4005003
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发表时间：
2014-12-01
影响因子：
3
通讯作者：
Piard, Jonathan
中科院分区：
文献类型：
--
作者：
Piard, Jonathan
通过温度控制的紫外-可见光谱测量，研究了溶剂对 1',3'-二氢-1',3',3'-三甲基-6-硝基螺(2H-1-苯并吡喃-2,2'-2H-吲哚) (6-NO2-BIPS) 的吸收光谱和逆反应动力学的影响。事实证明，五种不同溶剂（甲苯、THF、乙腈、DMSO 和乙醇）在多种温度下的逆反应过程遵循一级动力学。从所有溶剂的吸光度衰减曲线中提取动力学参数（E-a、A、tau、Delta H-#、Delta S-# 和 Delta G(#)），并提出了一个基于溶剂化机制的简单模型，与实验结果非常吻合。这种光致变色化合物在其部花青形式中也表现出强的溶剂化变色现象。所有这些实验都是为了说明具有本科物理化学理论背景的学生的溶剂对动力学过程和光学性质的影响。所描述的所有实验都可以在物理化学本科实验室中进行。
The solvent influence on the absorption spectra and the kinetics of the back reaction of the 1',3'-dihydro-1',3',3'-trimethyl-6-nitrospiro(2H-1-benzopyran-2,2'-2H-indole) (6-NO2-BIPS) has been investigated by means of temperature-controlled, UV-visible spectroscopic measurements. The back reaction process was proved to follow first-order kinetics for five different solvents (toluene, THF, acetonitrile, DMSO, and ethanol) at several temperatures. Kinetics parameters (E-a, A, tau, Delta H-#, Delta S-#, and Delta G(#)) were extracted from absorbance decay profiles for all solvents, and a simple model based on solvation mechanism was proposed in good agreement with experimental results. Such a photochromic compound also exhibits strong solvatochromism in its merocyanine form. All these experiments were performed to illustrate solvent effects on kinetic processes and optical properties for students with an undergraduate physical chemistry theoretical background. All the experiments described could be performed in a physical chemistry undergraduate laboratory.