van 't Hoff Institute for Molecular Sciences, Universiteit van Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands.
Chemphyschem. 2021 Jan 18;22(2):141-153. doi: 10.1002/cphc.202000927. Epub 2020 Dec 22.
The interpretation of 36 charge neutral 'contact pairs' from the IsoStar database was supported by DFT calculations of model molecules 1-12, and bimolecular adducts thereof. The 'central groups' are σ-hole donors (H O and aromatic C-I), π-hole donors (R-C(O)Me, R-NO and R-C F ) and for comparison R-C H (R=any group or atom). The 'contact groups' are hydrogen bond donors X-H (X=N, O, S, or R C, or R C) and lone-pair containing fragments (R C-F, R-C≡N and R C=O). Nearly all the IsoStar distributions follow expectations based on the electrostatic potential of the 'central-' and 'contact group'. Interaction energies (ΔE ) are dominated by electrostatics (particularly between two polarized molecules) or dispersion (especially in case of large contact area). Orbital interactions never dominate, but could be significant (∼30 %) and of the n/π→σ*/π* kind. The largest degree of directionality in the IsoStar plots was typically observed for adducts more stable than ΔE ≈-4 kcal⋅mol , which can be seen as a benchmark-value for the utility of an interaction in crystal engineering. This benchmark could be met with all the σ- and π-hole donors studied.
从 IsoStar 数据库中选择了 36 对中性“接触对”进行了诠释，其解释依据是对模型分子 1-12 及其双分子加合物的 DFT 计算。“中心基团”是 σ-hole 供体（H O 和芳香族 C-I）、π-hole 供体（R-C(O)Me、R-NO 和 R-C F ），并进行了 R-C H （R=任何基团或原子）的对比。“接触基团”是氢键供体 X-H（X=N、O、S 或 R C 或 R C ）和含有孤对电子的片段（R C-F、R-C≡N 和 R C=O）。几乎所有的 IsoStar 分布都符合基于“中心-”和“接触组”静电势的预期。相互作用能（ΔE ）主要由静电（特别是在两个极化分子之间）或色散（特别是在接触面积较大的情况下）决定。轨道相互作用从未占主导地位，但可能具有重要意义（∼30%），并且属于 n/π→σ*/π*类型。在 IsoStar 图中，通常观察到方向性最大的是比 ΔE ≈-4 kcal⋅mol 更稳定的加合物，这可以作为晶体工程中相互作用有用性的基准值。所有研究的 σ-和 π-hole 供体都可以达到该基准值。
