Substituent Effects in CH Hydrogen Bond Interactions: Linear Free Energy Relationships and Influence of Anions

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• 作者：Blakely W. Tresca ; Ryan J. Hansen ; Calvin V. Chau ; Benjamin P. Hay ; Lev N. Zakharov ; Michael M. Haley ; Darren W. Johnson
• 刊名：Journal of the American Chemical Society
• 出版年：2015
• 出版时间：December 2, 2015
• 年：2015
• 卷：137
• 期：47
• 页码：14959-14967
• 全文大小：557K
• ISSN：1520-5126

文摘

Aryl CH hydrogen bonds (HBs) are now commonly recognized as important factors in a number of fields, including molecular biology, stereoselective catalysis, and anion supramolecular chemistry. As the utility of CH HBs has grown, so to has the need to understand the structure鈥揳ctivity relationship for tuning both their strength and selectivity. Although there has been significant computational effort in this area, an experimental study of the substituent effects on CH HBs has not been previously undertaken. Herein we disclose a systematic study of a single CH HB by using traditional urea donors as directing groups in a supramolecular binding cavity. Experimentally determined association constants are examined by a combination of computational (electrostatic potential) and empirical (蟽_m and 蟽_p) values for substituent effects. The dominance of electrostatic parameters, as observed in a computational DFT study, is consistent with current CH HB theory; however, a novel anion dependence of the substituent effects is revealed in solution.