Santos Rodolfo A, Santos- Carlos V, Aguiar Eduardo C, Carneiro Neto Albano N, Moura Renaldo T
Department of Chemistry, Federal University of Paraiba, João Pessoa, Brazil.
Academic Unit of Belo Jardim, Federal Rural University of Pernambuco, Belo Jardim, Brazil.
J Comput Chem. 2025 Jul 15;46(19):e70166. doi: 10.1002/jcc.70166.
Hydrogen bonds are essential chemical interactions that occur in various systems, playing a critical role in determining molecular structures, dynamics, and reactivity. While quantum chemical methods such as Quantum Theory of Atoms in Molecules (QTAIM) and Natural Bond Orbital (NBO) analyses have traditionally been used to explore these interactions, this work introduces the Chemical Bond Overlap (OP) Model and its topological (TOP) descriptors as a complementary approach for analyzing orbital overlap contributions in hydrogen bonds. The study reports a systematic investigation of a series of hydrogen-bonded systems (a total of 25 systems), demonstrating how electron-donating and electron-withdrawing substituents influence bond characteristics. The results reveal that OP/TOP effectively captures the effects of electronic perturbations, offering insights into the (X) interactions and serving as a complementary approach to QTAIM, NBO, and local vibrational modes theory (LVM). Notably, for nonconventional hydrogen bonds ( ), the OP/TOP model, consistent with LVM, correctly captures the expected increase in interaction strength for . This agrees with the higher electrophilicity of the hydrogen in , as indicated by its lower pKa and weaker CH bond dissociation energy. Additionally, the inclusion of electron-donating groups significantly enhances lone pair antibonding orbital interactions, increasing NBO occupancy and electron density at the hydrogen bond critical point (BCP), as reflected by a decrease in and an increase in . This behavior consistently indicates hydrogen bond strengthening across QTAIM, NBO, and OP/TOP descriptors. Calculations were performed using the B97X-D/def2-TZVP level of theory. The findings establish OP/TOP as a powerful tool for computational chemistry, particularly in the study of weak intermolecular interactions and molecular design.
氢键是各种体系中存在的重要化学相互作用，在决定分子结构、动力学和反应活性方面起着关键作用。虽然诸如分子中的原子量子理论（QTAIM）和自然键轨道（NBO）分析等量子化学方法传统上用于探索这些相互作用，但本工作引入了化学键重叠（OP）模型及其拓扑（TOP）描述符，作为分析氢键中轨道重叠贡献的一种补充方法。该研究报告了对一系列氢键体系（共25个体系）的系统研究，展示了供电子和吸电子取代基如何影响键的特性。结果表明，OP/TOP有效地捕捉了电子扰动的影响，为（X）相互作用提供了见解，并作为QTAIM、NBO和局部振动模式理论（LVM）的补充方法。值得注意的是，对于非常规氢键（），OP/TOP模型与LVM一致，正确地捕捉到了（）相互作用强度预期的增加。这与（）中氢的较高亲电性一致，其较低的pKa和较弱的C-H键解离能表明了这一点。此外，引入供电子基团显著增强了孤对反键轨道相互作用，增加了NBO占据率和氢键临界点（BCP）处的电子密度，这表现为（）的降低和（）的增加。这种行为在QTAIM、NBO和OP/TOP描述符中都一致表明氢键增强。计算使用了B97X-D/def2-TZVP理论水平。这些发现确立了OP/TOP作为计算化学的一种强大工具，特别是在弱分子间相互作用和分子设计的研究中。
