How to Model Inter- and Intramolecular Hydrogen Bond Strengths with Quantum Chemistry

This article presents the computation of both inter- and intramolecular hydrogen bond strengths from first-principles. Quantum chemical calculations conducted at the dispersion-corrected density functional theory level including free energy and solvation contributions are conducted for (i) one-to-one hydrogen-bonded complexes of alcohols to N-methyl pyrrolidinone measured by an infrared spectroscopy method and (ii) a set of experimental intramolecular hydrogen bond-forming phenol and pyrrole compounds, with intramolecular hydrogen bond strengths derived from a nuclear magnetic resonance method. The computed complexation free energies in solution show a correlation to experiment of R2 = 0.74 with a root mean square error of 4.85 kJ mol–1. The intramolecular hydrogen bonding free energies in solution show a correlation of R2 = 0.79 with a root mean square error of 5.51 kJ mol–1. The results of this study can be used as a guide on how to build reliable quantum chemical databases for computed hydrogen bonding strengths.本文基于第一性原理（first-principles）计算了分子间与分子内氢键的键强。本研究采用色散校正密度泛函理论（dispersion-corrected density functional theory）方法开展量子化学计算，同时纳入自由能与溶剂化效应的贡献，针对两类体系展开研究：(i) 醇与N-甲基吡咯烷酮（N-methyl pyrrolidinone）的一对一氢键复合物，该复合物的实验数据通过红外光谱法测得；(ii) 一组可形成分子内氢键的酚类与吡咯类实验化合物，其分子内氢键键强由核磁共振（nuclear magnetic resonance）法推导得出。所计算得到的溶液中复合物形成自由能与实验值的相关系数R²为0.74，均方根误差为4.85 kJ·mol⁻¹。溶液中分子内氢键形成自由能与实验值的相关系数R²为0.79，均方根误差为5.51 kJ·mol⁻¹。本研究结果可为构建用于计算氢键键强的可靠量子化学数据库提供参考依据。