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Understanding Dispersion Interactions in Molecular Chemistry Cite This: Phys PCCP View Article Online EDITORIAL View Journal | View Issue Understanding dispersion interactions in molecular chemistry Cite this: Phys. Chem. Chem. Phys., 2021, 23, 8960 a b c Ju¨rgen Janek, Peter R. Schreiner and Martin A. Suhm DOI: 10.1039/d0cp90285c rsc.li/pccp London dispersion interactions have It offers two competing hydrogen bond the present themed collection, the OH been known for more than 90 years,1 acceptor sites with rather different prop- stretching mode is found to be a particu- but their role in molecular chemistry erties. The ether oxygen is a classical larly sensitive probe. has remained underrated among che- electrostatic attractor, which is signifi- When switching from water and ethers mists until recently,2 and the missing cantly attenuated by conjugation with to ketones, additional isomerism arises due long-range electron correlation in popu- the aromatic substituents. The latter to the better defined barrier between the 3 lar density functionals that is largely offer dispersion-favourable p-electron- oxygen lone electron pairs.5 This gives rise responsible for London dispersion rich faces and C–H bonds for non- to subtle intermolecular energy balances accentuated the problem earlier in this classical hydrogen bonding. Their deli- which are largely controlled by the electro- century. To enhance awareness and cate interplay can be modulated by tor- nic structure, without too much interfer- understanding of these universally sion angles. The Schnell and Gerhards ence from zero-point energy effects. That attractive forces in the context of chem- groups study the torsional dynamics and allows for a more direct probing of electro- istry, the Bunsentagung 2020 (General its modulation by water as one of the nic structure inaccuracies and an infrared Published on 12 April 2021. Downloaded 9/28/2021 6:22:07 AM. Assembly of the German Bunsen Society least dispersively driven of all hydrogen- study of acetophenone–alcohol pairings for Physical Chemistry, now shifted to bonded donors by multi-spectroscopic reveals a subtle failure of dispersion- 2022 due to the Covid-19 pandemic) approaches (DOI: 10.1039/D0CP04104A). corrected density functionals to reproduce and a themed Phys. Chem. Chem. Phys. While the first water remains rather the structure of a bulky alcohol–cyclopropyl collection of articles were initiated. undecided between electrostatics and derivative (DOI: 10.1039/C9CP06128B). It The present collection comprises dispersion, additional hydration is direc- appears that the DFT functionals prefer a 12 articles, more than half of which are ted by hydrogen bond cooperativity and more compact structure than experimen- co-authored by principal investigators London dispersion now only determines tally observed, but microwave studies could and their teams from the priority pro- secondary binding preferences. As the provide a valuable test of this conjecture. gramme SPP 1807 on ‘‘Control of London binding sites typically differ in their The question of hydrogen bonding vs. dispersion interactions in molecular chem- chemical nature, such subtle energy dif- dispersive interactions was addressed istry’’, funded by the German Research ferences are simultaneously controlled multi-experimentally at room temperature Foundation between 2015 and 2021. by electronic and zero-point energy or for liquid racemic ibuprofen, the popular Diphenylether has been a frequently nuclear quantum effects. anti-inflammatory drug (DOI: 10.1039/ visited molecular object in this context.4 Even for bulk liquid water, dispersion C9CP06641A).Itwasfoundthathalfof interactions are shown to play an impor- the vaporization enthalpy can be attributed a Physical Chemistry Institute, Justus Liebig University Giessen, Heinrich-Buff-Ring 17, 35392 Giessen, tant role in a theoretical study employing to carboxylic acid hydrogen bonding, and Germany classical molecular dynamics (DOI: 10. less than half of that enthalpy needs to be b Institute of Organic Chemistry, Justus Liebig 1039/C9CP06335H). While zero-point invested to break one of the double hydro- University Giessen, Heinrich-Buff-Ring 58, 35392 energy effects are neglected in such an gen bonds in the liquid. Carboxylic acid Giessen, Germany approach, correction schemes are devel- dissociation energies are higher at low c Georg-August-Universita¨tGo¨ttingen, Institute of 6 Physical Chemistry, Tammannstr. 6, 37077 oped to overcome this and other defi- temperature due to the reduced weak- Go¨ttingen, Germany ciencies. As in other studies contained in ening effect of thermal motion, and are 8960 | Phys. Chem. Chem. Phys., 2021, 23, 8960–8961 This journal is © the Owner Societies 2021 View Article Online Editorial PCCP perhaps even chirality-dependent.7 The Coincidentally, size-dependent London chemistry—Reconsidering steric effects, gas phase after sublimation may still dispersion forces also play a role in the Angew. Chem., Int. Ed., 2015, 54, 12274, exhibit molecular aggregation in such ball-mill dispersion of inorganic solids in DOI: 10.1002/anie.201503476. systems. In the case of ionic liquids, liquids by acting as surfactants (DOI: 10. 3 S. Kristya´n and P. Pulay, Can (semi)- thermal and gas phase aggregation 1039/C9CP05722F). Clearly, the systema- local density functional theory account effects are particularly important due tic modification of materials with disper- for the London dispersion forces?, to the combined cohesion by ionic sion energy donors allows for a Chem. Phys. Lett., 1994, 229, 175, DOI: and dispersive forces (DOI: 10.1039/ favourable tuning of material properties. 10.1016/0009-2614(94)01027-7. D0CP05439A). The effect of thermal This is further explored for the still 4 F. Dietrich, D. Bernhard, M. Fatima, motion on sublimation enthalpies can poorly understood field of fluorous inter- C. Pe´rez, M. Schnell and M. Gerhards, be sizeable, as revealed for a large crystal- actions in the case of phthalocyanine The effect of dispersion on the structure lographic database which includes sev- films (DOI: 10.1039/C9CP06709D). of diphenyl ether aggregates, Angew. eral achiral carboxylic acid binding Common themes in this collection Chem., Int. Ed., 2018, 57, 9534, DOI: motifs (DOI: 10.1039/C9CP04488D). include the multi-experimental character 10.1002/anie.201801842. When analysing dispersion interactions of many studies, the use of libraries of 5A.Poblotzki,H.C.Gottschalkand in the condensed phase, such thermal compounds to make a case, the impor- M. A. Suhm, Tipping the scales: Spectro- and volume effects should not be tance of gas-phase reference studies and scopic tools for intermolecular energy neglected, but inclusion of chiral build- the application of experimental bench- balances, J. Phys. Chem. Lett., 2017, ing blocks in the database is encouraged, marking strategies.9 Many investigations 8, 5656, DOI: 10.1021/acs.jpclett.7b02337. because it allows for subtly different use DLPNO-CCSD(T) wave function cal- 6F.Kollipost,R.WugtLarsen,A.V. effects in the solid state.8 culations for DFT checking and the Domanskaya, M. No¨renberg and M. A. A pronounced case of chirality- resulting LED scheme for energy Suhm, Communication: The highest dependent cohesion was found in dimers decomposition,10 and they usually rely frequency hydrogen bond vibration of vicinal diols (DOI: 10.1039/C9CP04943F), on harmonic estimates for the back- and an experimental value for the dis- again using a multi-experimental approach. correction of vibrational contributions. sociation energy of formic acid dimer, Transiently enantiomeric conformations Once the effects of dispersion interac- J. Chem. Phys., 2012, 136, 151101, DOI: interact much more strongly with each tions in molecular chemistry are better 10.1063/1.4704827. other, and this heterochiral preference can understood by physico-chemical methods 7G.L.Perlovich,S.V.Kurkov,L.Kr. be modulated by dispersion interactions and by dispersion-corrected density func- Hansen and A. Bauer-Brandl, Thermo- among bulky substituents. The opposite tional theory,11 they can be used even more dynamics of sublimation, crystal lattice strategy of using permanent chirality to systematically and rationally for chemical energies, and crystal structures of race- disentangle the subtle interplay between control purposes. This is a declared goal of mates and enantiomers: (+)- and dispersively dominated and classical hydro- the priority programme on ‘‘Control of (Æ)-Ibuprofen, J. Pharm. Sci., 2004, Published on 12 April 2021. Downloaded 9/28/2021 6:22:07 AM. gen bonds was successfully applied to ben- London dispersion interactions in molecular 93, 654, DOI: 10.1002/jps.10586. zyl alcohol (DOI: 10.1039/D0CP04825A), chemistry’’ and of this themed collection. 8 A. Otero-de-la-Roza, J. E. Hein and where again a phenyl group serves as the We thank all contributing authors, E. R. Johnson, Reevaluating the stability dispersion energy anchor. Robert Medel for the figure design, the and prevalence of conglomerates: Impli- Inorganic dispersion energy donors PCCP office and particularly Dr Colin King cations for preferential crystallization, based on bismuth were explored in the for assembling and processing this themed Cryst. Growth Des., 2016, 16, 6055, context of intra- vs. intermolecular and collection and the DFG (German Research DOI: 10.1021/acs.cgd.6b01088. halide- vs. p-competition (DOI: 10.1039/ Foundation) for topical funding and con- 9 R. A. Mata and M. A. Suhm, Bench- C9CP06924K). The almost purely disper- tinuing support. We dedicate this themed marking quantum chemical methods: sive Bi–arene
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