Binding Studies between Triethylene Glycol-Substituted Monopyrrolotetrathiafulvalene Derivatives and Cyclobis(paraquat-p-phenylene)

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• 作者：Sune Nygaard ; Camilla N. Hansen ; Jan O. Jeppesen
• 刊名：Journal of Organic Chemistry
• 出版年：2007
• 出版时间：March 2, 2007
• 年：2007
• 卷：72
• 期：5
• 页码：1617 - 1626
• 全文大小：213K
• 年卷期：v.72,no.5(March 2, 2007)
• ISSN：1520-6904

文摘

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The synthesis of several pi.gif" BORDER=0 >-electron-donating monopyrrolotetrathiafulvalene (MPTTF) derivatives, whichconceptually can be divided into three classes containing none, one, or two triethylene glycol (TEG)substituents, is described. In all cases, the complexation between the pi.gif" BORDER=0 >-electron donating MPTTF unitand the pi.gif" BORDER=0 >-electron-deficient tetracationic cyclophane cyclobis(paraquat-p-phenylene) (CBPQT⁴⁺) has beeninvestigated using UV-vis dilution techniques. The results reveal that the strength of the binding betweenMPTTF derivatives and CBPQT⁴⁺ is directly correlated to the pi.gif" BORDER=0 >-electron donating properties of the MPTTFderivatives. However, the pi.gif" BORDER=0 >-electron-donating properties of the MPTTF derivatives is not the only factorof importance. The results enclosed in the present studies demonstrate that the TEG substituents assistthe complexation process most likely on account of their capacity to participate in [C-H···O] hydrogenbonding interactions with some of the pha.gif" BORDER=0>-CH protons in the bipyridinium units of CBPQT⁴⁺ and thestabilizing effect that attachment of one or two TEG substituents to the MPTTF unit exerts uponcomplexation with CBPQT⁴⁺ has been quantified to approximately 0.3 and 0.5 kcal mol^-1, respectively.These results serve to lay an extended foundation for the understanding of which buttons to push whenit comes to improve the design of bistable molecular switches based on (MP)TTF and CBPQT⁴⁺.