Computational Insights into Processes Underlying the Amine-Induced Fluorescence Quenching of a Stimuli-Responsive Phenol-Based Hexameric Foldamer Host

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• 作者：Chang Sun ; Ying Liu ; Jiaqiang Liu ; Yu-Jing Lu ; Lin Yu ; Kun Zhang ; Huaqiang Zeng
• 刊名：Journal of Organic Chemistry
• 出版年：2014
• 出版时间：April 4, 2014
• 年：2014
• 卷：79
• 期：7
• 页码：2963-2973
• 全文大小：799K
• 年卷期：v.79,no.7(April 4, 2014)
• ISSN：1520-6904

文摘

Recently, we reported that amine-induced folding of a more fluorescent, more linear structure into less fluorescent, more curved or helically folded states enables patterned recognitions of amines and ammoniums. In this article, we have carried out extensive ab initio calculations at the B3LYP/6-31G level that not only map out the detailed amine-induced folding/quenching pathways and plausible folding/quenching species but also surprisingly reveal the binding of amines to anionic hosts to be unusually cooperative in a way that the progressively more charged anionic hosts act as increasingly better 鈥渁mine trappers鈥? Accordingly amine-dependent folding occurs via a synergistic action of amines鈥?basicity and the progressively more curved backbone of the host. Although a hexamer carrying four deprotonable hydroxyl sites can reach a tetra-anionic state, mono-, di-, tri-, and tetra-anionic complexes likely dominate as the major quenching species in the presence of, respectively, 2, 4, 8, and 72 equiv of primary amines.