Effect of Pressure on [2]Pseudorotaxane Formation and Decomplexation and Their Corresponding Activation Volumes

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• 作者：Yuji Tokunaga ; Nanae Wakamatsu ; Norihiro Ohiwa ; Osamu Kimizuka ; Akihiro Ohbayashi ; Koichiro Akasaka ; Susumu Saeki ; Kenji Hisada ; Tatsuhiro Goda ; Youji Shimomura
• 刊名：Journal of Organic Chemistry
• 出版年：2010
• 出版时间：August 6, 2010
• 年：2010
• 卷：75
• 期：15
• 页码：4950-4956
• 全文大小：935K
• 年卷期：v.75,no.15(August 6, 2010)
• ISSN：1520-6904

文摘

In this study, we investigated the effect of pressure on the formation and decomplexation of [2]pseudorotaxanes. High pressure accelerated the formation of [2]pseudorotaxanes in an aprotic nonpolar solvent (CDCl₃/CD₃CN) via the slipping approach when using two crown ether/secondary ammonium salt systems: dibenzo[24]crown-8/bis(cyclohexylmethyl)ammonium salt (1a/2a) and tetrabenzo[24]crown-8/dibenzylammonium salt (1b/2b). The influence of pressure on the rate constants for the formation of the [2]pseudorotaxanes 3a and 3b revealed activation volumes (ΔV) of −2.5 and −4.6 cm³ mol⁻¹, respectively, at 303 K and zero pressure. We also investigated the effect of pressure on the decomplexation of the [2]pseudorotaxanes 3a and 3b in a polar solvent (DMSO-d₆/CDCl₃), obtaining activation volumes of −0.9 and −0.4 cm³ mol⁻¹, respectively, at 303 K and zero pressure. Moreover, we calculated the activation parameters for the decomplexation processes on the basis of transition state theory at each pressure.