Wu Bowei, Hazrah Arsh S, Seifert Nathan A, Oswald Sönke, Jäger Wolfgang, Xu Yunjie
Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2R3, Canada.
Department of Chemistry and Chemical & Biomedical Engineering, University of New Haven, 300 Boston Post Rd, West Haven, Connecticut 06516, United States.
J Phys Chem A. 2021 Dec 9;125(48):10401-10409. doi: 10.1021/acs.jpca.1c09058. Epub 2021 Nov 30.
Rotational spectra of the 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP)···water complex were measured using a chirped pulse Fourier-transform microwave spectrometer. The spectral analyses, aided by density functional theory calculations, reveal two HFIP···water isomers: one previously reported, HFIP (HFIP)···water ( 5650-5657), and a new isomer, HFIP (HFIP)···water. To confirm the identity of the new isomer, rotational spectra of seven of its deuterated species were also measured and analyzed. Both the experimental and theoretical pieces of evidence indicate that the intermolecular interaction with water preferentially stabilizes the HFIP monomer configuration over the global minimum configuration, HFIP. The relative energy difference between these monomeric forms is 4.1 kJ mol and decreases to 2.5 kJ mol in the respective monohydrates at the B3LYP-D3(BJ)/def2-QZVP level of theory. Both rigid and relaxed potential energy surface scans were carried out to gain insights into the large-amplitude water motions in HFIP···water. The nonobservation of a water tunneling splitting in HFIP···water has been explained to be a result of a barrier-less (after zero-point-energy correction) pathway for the water motion, whereas in HFIP···water, a relatively large water tunneling barrier was identified as the cause of barely resolved water tunneling splittings. Noncovalent interaction and quantum theory of atoms and molecule analyses were used to evaluate the changes in HFIP···water when going from the minimum to the transition state in terms of attractive interactions such as the OH···H and OH···F contacts. The effect of fluorination is discussed by comparing the vastly different binding topologies of isopropanol···water and HFIP···water.
使用啁啾脉冲傅里叶变换微波光谱仪测量了1,1,1,3,3,3 - 六氟 - 2 - 丙醇（HFIP）···水络合物的转动光谱。在密度泛函理论计算的辅助下进行光谱分析，揭示了两种HFIP···水异构体：一种是先前报道的HFIP（HFIP）···水（ 5650 - 5657），以及一种新的异构体HFIP（HFIP）···水。为了确认新异构体的身份，还测量并分析了其七种氘代物种的转动光谱。实验和理论证据均表明，与水的分子间相互作用相比于全局最低构型HFIP，优先稳定了HFIP单体构型。在B3LYP - D3(BJ)/def2 - QZVP理论水平下，这些单体形式之间的相对能量差为4.1 kJ/mol，在各自的一水合物中降至2.5 kJ/mol。进行了刚性和松弛势能面扫描，以深入了解HFIP···水中水的大幅度运动。HFIP···水中未观察到水隧穿分裂，这被解释为水运动的无障碍（零点能量校正后）路径的结果，而在HFIP···水中，确定相对较大的水隧穿势垒是水隧穿分裂几乎无法分辨的原因。非共价相互作用和原子与分子量子理论分析被用于评估从最低态到过渡态时HFIP···水在诸如OH···H和OH···F接触等吸引相互作用方面的变化。通过比较异丙醇···水和HFIP···水截然不同的结合拓扑结构来讨论氟化的影响。
