Quantifying Intrinsic Ion-Driven Conformational Changes in Diphenylacetylene Supramolecular Switches with Cryogenic Ion Vibrational Spectroscopy

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• 作者：Arron B. Wolk ; Etienne Garand ; Ian M. Jones ; Andrew D. Hamilton ; Mark A. Johnson
• 刊名：The Journal of Physical Chemistry A
• 出版年：2013
• 出版时间：July 25, 2013
• 年：2013
• 卷：117
• 期：29
• 页码：5962-5969
• 全文大小：406K
• 年卷期：v.117,no.29(July 25, 2013)
• ISSN：1520-5215

文摘

We report how two flexible diphenylacetylene (DPA) derivatives distort to accommodate both cationic and anionic partners in the binary X^卤路DPA series with X = TMA⁺ (tetramethylammonium), Na⁺, Cl^{鈥?/sup>, Br鈥?/sup>, and I鈥?/sup>. This is accomplished through theoretical analysis of X卤路DPA路2Db>2b> vibrational spectra, acquired by predissociation of the weakly bound Db>2b> adducts formed in a 10 K ion trap. DPA binds the weakly coordinating TMA+ ion with an arrangement similar to that of the neutral compound, whereas the smaller Na+ ion breaks all intramolecular H-bonds yielding a structure akin to the transition state for interconversion of the two conformations in neutral DPA. Halides coordinate to the urea NH donors in a bidentate H-bonded configuration analogous to the single intramolecular H-bonded motif identified at high chloride concentrations in solution. Three positions of the 鈥渟witch鈥?are thus identified in the intrinsic ion accommodation profile that differ by the number of intramolecular H-bonds (0, 1, or 2) at play.}