High-resolution diffusion-ordered spectroscopy to probe the microenvironment of JandaJel and Merrifield resins.
High-resolution diffusion-ordered spectroscopy to probe the microenvironment of JandaJel and Merrifield resins.
复制标题
用于探测 JandaJel 和 Merrifield 树脂微环境的高分辨率扩散有序光谱。
DOI：
10.1021/jo034152z
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
Janda,KimD
中科院分区：
文献类型：
--
作者：
Gambs,Celine;Dickerson,TobinJ;Mahajan,Suresh;Pasternack,LauraB;Janda,KimD
The success of organic reactions performed on a gel-phase resin is highly dependent on the accessibility of solvents, catalysts, and reagents to the interior of the resin. A variety of techniques including EPR, fluorescence, and Hildebrand solubility parameters (δ) have been used to probe reaction capabilities and in particular the microenvironment of a gel-phase resin. To provide a more detailed picture of the matrix in question, researchers have turned to NMR for the determination of the diffusion coefficients of solvents and small molecules in swollen beads to provide a means to compare the microenvironment of swollen beads. Since Merrifield andJandaJel resins display different swelling properties and have significantly different kinetic behavior, we undertook a comparative study of the diffusion coefficients of solvents and small molecules in both resins by high-resolution1H DOSY NMR. Our results show the following: (1) diffusion values for all studied solvents and small molecules are 20−30% higher inJandaJel compared to Merrifield resins, (2) in the absence of interactions between the resin and a given molecule, the diffusion values mirror the swelling properties of the resin, and (3) in the presence of strong intermolecular interactions between the gel and the considered molecule, the diffusion behavior in the gel is primarily influenced by the strength of the interactions and secondarily by the swelling properties of the resin. These results clearly show that the microenvironment ofJandaJels is more “solution-like” than that of Merrifield resins, presumably due to the higher swelling capacity.
