Moaven Shiva, Vander Griend Douglas A, Johnson Darren W, Pluth Michael D
Department of Chemistry and Biochemistry, Materials Science Institute 1253 University of Oregon Eugene OR 97403 USA
Department of Chemistry and Biochemistry, Calvin University Grand Rapids MI 49546 USA.
Chem Sci. 2025 May 6. doi: 10.1039/d5sc01329a.
Association constant ( ) measurements provide fundamental information on host-guest interactions in supramolecular chemistry and other areas of science. Here we report the use of FTIR spectroscopy to measure the values across three classes of host-guest complexes that involve hydrogen bonding and halogen bonding. This approach can be performed with minimal sample preparation, does not require deuterated solvents, can measure association based on changes in host or guest vibrations, and benefits from a much shorter timescale than NMR spectroscopy. Due to its fast timescale, FTIR spectroscopy also provides details on host/guest conformational changes, such as the presence of unsymmetrical host conformations that are not in the ideal binding conformation until treatment with a suitable guest. These changes would not be observable by standard time-averaged NMR titration measurements. Using this approach, we demonstrated the capabilities and challenges of this technique to investigate host-guest interactions of three anion receptors that use hydrogen or halogen bonding with both mono- and polyatomic anions. In addition to directly observing how host-guest interactions impact bonding within the individual molecules, we also demonstrate that global fitting of the FTIR spectra is an effective and robust approach to measure values of these host-guest complexes. We anticipate that this method will provide a new and useful approach to investigating the dynamics and specific interactions across broad areas of science.
缔合常数（ ）测量为超分子化学及其他科学领域中的主客体相互作用提供了基础信息。在此，我们报道了利用傅里叶变换红外光谱（FTIR）来测量三类涉及氢键和卤键的主客体配合物的 值。这种方法所需的样品制备极少，不需要氘代溶剂，可以基于主体或客体振动的变化来测量缔合，并且与核磁共振光谱相比，其时间尺度要短得多。由于其时间尺度快，FTIR光谱还能提供主/客体构象变化的细节，比如存在不对称的主体构象，这些构象在未用合适的客体处理之前并不处于理想的结合构象。这些变化通过标准的时间平均核磁共振滴定测量是无法观察到的。利用这种方法，我们展示了该技术在研究三种利用氢键或卤键与单原子和多原子阴离子相互作用的阴离子受体的主客体相互作用时的能力和挑战。除了直接观察主客体相互作用如何影响单个分子内的键合外，我们还证明了FTIR光谱的全局拟合是一种测量这些主客体配合物 值的有效且稳健的方法。我们预计这种方法将为研究广泛科学领域中的动力学和特定相互作用提供一种新的有用途径。
