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Cover of ChemPhysChem features comprehensive evaluation by Tiddo Mooibroek of σ‐ and π‐hole interactions

25 January 2021

A paper by Dr Tiddo J. Mooibroek of the Van 't Hoff Institute for Molecular Sciences (HIMS) is featured on the cover of the recent ChemPhysChem issue. In his paper, Mooibroek presents a comprehensive and comparative evaluation of different σ‐ and π‐hole interactions present in the IsoStar database. For this, he scrutinized carefully selected IsoStar database entries, supplemented by various DFT calculations. His study is of relevance to the assessment of σ‐ or π‐hole interactions that drive diverse processes such as protein folding, molecular recognition phenomena and crystal engineering.
Cover picture ChemPhysChem
The Front Cover of ChemPhysChem shows the IsoStar distributions of carbonyl fragments around several σ‐ and π‐hole donors. Such analyses and DFT calculations were used to assess the utility of several σ‐/π‐hole for crystal engineering. Image: ChemPhysChem/HIMS.

Abstract

The interpretation of 36 charge neutral ‘contact pairs’ from the IsoStar database was supported by DFT calculations of model molecules, and bimolecular adducts thereof. The ‘central groups’ are σ‐hole donors (H2O and aromatic C−I), π‐hole donors (R−C(O)Me, R−NO2 and R−C6F5) and for comparison R−C6H5 (R=any group or atom). The ‘contact groups’ are hydrogen bond donors X−H (X=N, O, S, or R2C, or R3C) and lone‐pair containing fragments (R3C−F, R−C≡N and R2C=O). Nearly all the IsoStar distributions follow expectations based on the electrostatic potential of the ‘central‐’ and ‘contact group’. Interaction energies (ΔEBSSE) 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 ΔEBSSE≈−4 kcal⋅mol−1, 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.

Paper

Tiddo J. Mooibroek: DFT and IsoStar Analyses to Assess the Utility of σ‐ and π‐Hole Interactions for Crystal Engineering ChemPhysChem 2021 Vol.22, Issue 2 DOI: 10.1002/cphc.202000927

Mooibroek dedicates his paper to all scientists and essential workers that contributed to mitigate the crises that ensued after the outbreak of the Corona virus ‘SARS‐CoV‐2’.