Mulliken Center for Theoretical Chemistry, Institute of Physical and Theoretical Chemistry, University of Bonn, Beringstr. 4, 53115 Bonn, Germany.
Phys Chem Chem Phys. 2021 May 26;23(20):11635-11648. doi: 10.1039/d1cp01333e.
The strongly attractive noncovalent interactions of charged atoms or molecules with π-systems are important binding motifs in many chemical and biological systems. These so-called ion-π interactions play a major role in enzymes, molecular recognition, and for the structure of proteins. In this work, a molecular test set termed IONPI19 is compiled for inter- and intramolecular ion-π interactions, which is well balanced between anionic and cationic systems. The IONPI19 set includes interaction energies of significantly larger molecules (up to 133 atoms) than in other ion-π test sets and covers a broad range of binding motifs. Accurate (local) coupled cluster values are provided as reference. Overall, 19 density functional approximations, including seven (meta-)GGAs, eight hybrid functionals, and four double-hybrid functionals combined with three different London dispersion corrections, are benchmarked for interaction energies. DFT results are further compared to wave function based methods such as MP2 and dispersion corrected Hartree-Fock. Also, the performance of semiempirical QM methods such as the GFNn-xTB and PMx family of methods is tested. It is shown that dispersion-uncorrected DFT underestimates ion-π interactions significantly, even though electrostatic interactions dominate the overall binding. Accordingly, the new charge dependent D4 dispersion model is found to be consistently better than the standard D3 correction. Furthermore, the functional performance trend along Jacob's ladder is generally obeyed and the reduction of the self-interaction error leads to an improvement of (double) hybrid functionals over (meta-)GGAs, even though the effect of the SIE is smaller than expected. Overall, the double-hybrids PWPB95-D4/QZ and revDSD-PBEP86-D4/QZ turned out to be the most reliable among all assessed methods for the description of ion-π interactions, which opens up new perspectives for systems where coupled cluster calculations are no longer computationally feasible.
带电荷的原子或分子与π 体系之间的强吸引力非共价相互作用是许多化学和生物体系中重要的结合基序。这些所谓的离子-π 相互作用在酶、分子识别以及蛋白质结构中起着重要作用。在这项工作中，编译了一个名为 IONPI19 的分子测试集，用于研究离子-π 相互作用的分子内和分子间相互作用，该测试集在阴离子和阳离子系统之间具有很好的平衡。IONPI19 集包括显著更大分子（多达 133 个原子）的相互作用能，这比其他离子-π 测试集要大，并涵盖了广泛的结合基序。提供了准确的（局部）耦合簇值作为参考。总体而言，针对相互作用能，对 19 种密度泛函近似方法进行了基准测试，包括 7 种（meta）广义梯度近似（GGAs）、8 种杂化泛函和 4 种双杂化泛函，结合了三种不同的伦敦色散校正。将 DFT 结果与基于波函数的方法（如 MP2 和色散校正 Hartree-Fock）进行了比较。此外，还测试了半经验 QM 方法（如 GFNn-xTB 和 PMx 方法家族）的性能。结果表明，未校正色散的 DFT 严重低估了离子-π 相互作用，尽管静电相互作用主导了整体结合。因此，新的依赖于电荷的 D4 色散模型被发现始终优于标准 D3 校正。此外，沿着 Jacob 阶梯的函数性能趋势通常得到遵守，并且自相互作用误差的减少导致（双）杂化泛函优于（meta）广义梯度近似，尽管 SIE 的影响比预期的要小。总体而言，对于那些耦合簇计算不再具有计算可行性的体系，PW-PB95-D4/QZ 和 revDSD-PBEP86-D4/QZ 双杂化泛函是所有评估方法中最可靠的描述离子-π 相互作用的方法，这为这些体系开辟了新的前景。
