Department of Physical, Chemical and Natural Systems, Universidad Pablo de Olavide, 41013 Seville, Spain.
Department of Applied Physical Chemistry, Universidad Autonoma de Madrid, 28049 Madrid, Spain.
J Phys Chem Lett. 2023 Feb 9;14(5):1294-1300. doi: 10.1021/acs.jpclett.2c03832. Epub 2023 Feb 1.
The interaction of organic molecules with oxonium cations within their solvation shell may lead to the emergence of dynamic supramolecular structures with recurrently changing host-guest chemical identity. We illustrate this phenomenon in benchmark proton-bonded complexes of water with polyether macrocyles. Despite the smaller proton affinity of water versus the ether group, water in fact retains the proton in the form of HO, with increasing stability as the coordination number increases. Hindrance in many-fold coordination induces dynamic reversible (ether)·HO ⇌ (etherH)·HO interconversion. We perform infrared action ion spectroscopy over a broad spectral range to expose the vibrational signatures of the loose proton bonding in these systems. Remarkably, characteristic bands for the two limiting proton bonding configurations are observed in the experimental vibrational spectra, superimposed onto diffuse bands associated with proton delocalization. These features cannot be described by static equilibrium structures but are accurately modeled within the framework of molecular dynamics.
有机分子与溶剂化壳层中的氧鎓阳离子相互作用可能导致具有反复变化的主客体化学特性的动态超分子结构的出现。我们在水与聚醚大环的基准质子键合配合物中说明了这一现象。尽管水的质子亲和力小于醚基，但实际上水以 HO 的形式保留质子，随着配位数的增加稳定性增加。在多次配位中受阻会诱导动态可逆（醚）·HO ⇌ （醚 H）·HO 互变。我们在很宽的光谱范围内进行红外作用离子光谱学，以揭示这些体系中松散质子键的振动特征。值得注意的是，在实验振动光谱中观察到两种极限质子键合构型的特征带，叠加在与质子离域相关的漫射带上。这些特征不能用静态平衡结构来描述，但可以在分子动力学框架内准确建模。
