Faculty of Chemistry, University of Wrocław, ul. F. Joliot-Curie 14, 50-383 Wrocław, Poland.
Department of Fuels Chemistry and Technology, Wrocław University of Science and Technology, ul. Gdańska 7/9, 50-344 Wrocław, Poland.
Int J Mol Sci. 2021 May 14;22(10):5220. doi: 10.3390/ijms22105220.
The O-H...N and O-H...O hydrogen bonds were investigated in 10-hydroxybenzo[h]quinoline (HBQ) and benzo[h]quinoline-2-methylresorcinol complex in vacuo, solvent and crystalline phases. The chosen systems contain analogous donor and acceptor moieties but differently coupled (intra- versus intermolecularly). Car-Parrinello molecular dynamics (CPMD) was employed to shed light onto principle components of interactions responsible for the self-assembly. It was applied to study the dynamics of the hydrogen bonds and vibrational features as well as to provide initial geometries for incorporation of quantum effects and electronic structure studies. The vibrational features were revealed using Fourier transformation of the autocorrelation function of atomic velocity and by inclusion of nuclear quantum effects on the O-H stretching solving vibrational Schrödinger equation a posteriori. The potential of mean force (Pmf) was computed for the whole trajectory to derive the probability density distribution and for the O-H stretching mode from the proton vibrational eigenfunctions and eigenvalues incorporating statistical sampling and nuclear quantum effects. The electronic structure changes of the benzo[h]quinoline-2-methylresorcinol dimer and trimers were studied based on Constrained Density Functional Theory (CDFT) whereas the Electron Localization Function (ELF) method was applied for all systems. It was found that the bridged proton is localized on the donor side in both investigated systems in vacuo. The crystalline phase simulations indicated bridged proton-sharing and transfer events in HBQ. These effects are even more pronounced when nuclear quantization is taken into account, and the quantized Pmf allows the proton to sample the acceptor area more efficiently. The CDFT indicated the charge depletion at the bridged proton for the analyzed dimer and trimers in solvent. The ELF analysis showed the presence of the isolated proton (a signature of the strongest hydrogen bonds) only in some parts of the HBQ crystal simulation. The collected data underline the importance of the intramolecular coupling between the donor and acceptor moieties.
在真空、溶剂和晶体相中，研究了 10-羟基苯并[h]喹啉（HBQ）和苯并[h]喹啉-2-甲基间苯二酚复合物中的 O-H...N 和 O-H...O 氢键。所选体系包含类似的给体和受体部分，但连接方式不同（分子内与分子间）。Car-Parrinello 分子动力学（CPMD）被用来揭示负责自组装的相互作用的主要组成部分。它被应用于研究氢键的动力学和振动特征，并提供初始几何形状以纳入量子效应和电子结构研究。振动特征是通过原子速度自相关函数的傅里叶变换以及通过核量子效应求解振动薛定谔方程来揭示的。平均力势（Pmf）是为整个轨迹计算的，以从质子振动本征函数和本征值中推导出包含统计采样和核量子效应的 O-H 伸缩模式的概率密度分布。基于约束密度泛函理论（CDFT）研究了苯并[h]喹啉-2-甲基间苯二酚二聚体和三聚体的电子结构变化，而所有体系均应用电子局域函数（ELF）方法。结果发现，在真空条件下，在两个研究体系中，桥接质子都定位于给体侧。晶体相模拟表明 HBQ 中存在桥接质子共享和转移事件。当考虑核量子化时，这些效应更为明显，并且量子化的 Pmf 允许质子更有效地采样受体区域。CDFT 表明，在溶剂中，分析的二聚体和三聚体的桥接质子上存在电荷耗尽。ELF 分析表明，只有在 HBQ 晶体模拟的某些部分存在孤立质子（最强氢键的特征）。收集的数据强调了给体和受体部分之间的分子内耦合的重要性。
