π–π Interactions

Fagnani, Danielle E.; Sotuyo, Ania C.; Castellano, Ronald K.

doi:10.1016/b978-0-12-409547-2.12485-0

Cited by 18 publications

(27 citation statements)

References 319 publications

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“…1c). 10,11,15 Accurate calculations suggest that these two configurations are nearly iso-energetic, 13,[30][31][32][33] and indeed the short-range structure of liquid benzene that is inferred from neutron diffraction experiments is consistent with the coexistence of both orientations. 68 It happens that the interaction energy (stacking energy) in benzene dimer is nearly identical to that in of cyclohexane dimer.…”

Section: Resultsmentioning

confidence: 82%

“…Nevertheless, quadrupolar electrostatics is a recurring theme in discussion of π-π interactions, and has long been the principle paradigm through which paralleldisplaced π-stacking has been rationalized. [9][10][11][12][13][14][15][16][17][18][19][20][21] This conventional wisdom persists despite considerable evidence that charge penetration effects, which nullify or at least complicate classical electrostatic arguments, are significant at typical π-stacking dis- tances. [22][23][24][25][26][27][28][29] Benzene dimer is the archetypal π-stacked system and its conformational preferences are traditionally discussed in terms of several geometric isomers that are depicted in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…While the Hunter-Sanders model correctly predicts a slip-stacked structure for (C 6 H 6 ) 2 , in agreement with ab initio calculations, it does not explain the fact that (C 6 H 6 )• • • (C 6 F 6 ) also exhibits a parallel-offset structure, [34][35][36] despite quadrupolar electrostatic interactions that are attractive in the cofacial arrangement. Various studies have since suggested that the Hunter-Sanders model exaggerates the role of electrostatics, 3,[22][23][24][25][26]32,[37][38][39][40][41] however this model remains a widelydiscussed paradigm for π-π interactions, [9][10][11][12][13][14][15][16][17][18][19][20][21] highlighted in contemporary textbooks. 14,15 We have recently provided a clear and concise demonstration that the importance of electrostatics in π-π interactions has been misconstrued, and that the Hunter-Sanders model does not simply "overemphasize" electrostatics, 1 but is in fact qualitatively wrong and represents a fundamentally flawed framework for understanding π-π interactions.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Reinterpreting π-stacking

Carter-Fenk

Herbert

2020

Phys. Chem. Chem. Phys.

109

126

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Section: Resultsmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Reinterpreting π-stacking

Carter-Fenk

Herbert

2020

Phys. Chem. Chem. Phys.

109

126

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“…It adopts apartial face-to-face arrangement of the fluorine-rich parts of the molecules with alternating layers of the individual enantiomers ( Figures S4 and S5) and alternating interlayer distances of 3.381 and 3.610 .T his con-trasts to the solid structure of [4]helicene, which is characterized by the archetypical herringbone edge-to-face arrangement. [25] The synthesis of the planar bucky-bowl precursor 4bromo-13,16-difluorobenzo[s]picene( 4)o fIdpc-Br was then completed by as equence of benzylic bromination, Wittig reaction with 2-bromobenzaldehyde and as econd Mallory photocyclization.…”

Section: Resultsmentioning

confidence: 99%

Geodesic‐Planar Conjugates: Substituted Buckybowls—Synthesis, Photoluminescence and Electrochemistry

Bayer

Herberger

Holz

et al. 2020

Chemistry A European J

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CÀCc ross coupling products of bowl-shaped asindaceno[3,2,1,8,7,6-pqrstuv]picene (Idpc) and different planar arenes and ethynyl-arenes were synthesized. Photoluminescence as well as electrochemical properties of all products were investigated and complemented by time-dependent quantum chemical calculations. UV/Vis spectroelectro-chemistry investigations of the directly linked (Idpc) 2 indicated the absence of anyi ntramolecular charge-transfer transition of intermittently formed (Idpc) 2 C À .A ll coupling products showed fluorescence. Ferrocene-1-yl-Idpc was structurally characterized by X-ray diffraction and is ar are example of a ferrocene-containingb uckybowl exhibiting luminescence.

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“…1c). 10,11,15 Accurate calculations suggest that these two configurations are nearly iso-energetic, 13,[30][31][32][33] and indeed the short-range structure of liquid benzene that is inferred from neutron diffraction experiments is consistent with the coexistence of both orientations. 68 Cofacial Acenes Perpendicular Acenes It happens that the interaction energy (stacking energy) in benzene dimer is nearly identical to that in of cyclohexane dimer.…”

Section: Resultsmentioning

confidence: 82%

Reinterpreting π-Stacking

Carter-Fenk

Herbert

2020

Preprint

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The nature of pi-pi interactions has long been debated. The term "pi-stacking" is considered by some to be a misnomer, in part because overlapping pi-electron densities are thought to incur steric repulsion, and the physical origins of the widely-encountered "slip-stacked" motif have variously been attributed to either sterics or electrostatics, in competition with dispersion. Here, we use quantum-mechanical energy decomposition analysis to investigate pi-pi interactions in supramolecular complexes of polycyclic aromatic hydrocarbons, ranging in size up to realistic models of graphene, and for comparison we perform the same analysis on stacked complexes of polycyclic saturated hydrocarbons, which are cyclohexane-based analogues of graphane. Our results help to explain the short-range structure of liquid hydrocarbons that is inferred from neutron scattering, trends in melting-point data, the interlayer separation of graphene sheets, and finally band gaps and observation of molecular plasmons in graphene nanoribbons. Analysis of intermolecular forces demonstrates that aromatic pi-pi interactions constitute a unique and fundamentally quantum-mechanical form of non-bonded interaction. Not only do stacked pi-pi architectures enhance dispersion, but quadrupolar electrostatic interactions that may be repulsive at long range are rendered attractive at the intermolecular distances that characterize pi-stacking, as a result of charge penetration effects. The planar geometries of aromatic sp2 carbon networks lead to attractive interactions that are "served up on a molecular pizza peel", and adoption of slip-stacked geometries minimizes steric (rather than electrostatic) repulsion. The slip-stacked motif therefore emerges not as a defect induced by electrostatic repulsion but rather as a natural outcome of a conformation landscape that is dominated by van der Waals interactions (dispersion plus Pauli repulsion), and is therefore fundamentally quantum-mechanical in its origins. This reinterpretation of the forces responsible for pi-stacking has important implications for the manner in which non-bonded interactions are modeled using classical force fields, and for rationalizing the prevalence of the slip-stacked pi-pi motif in protein crystal structures.

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π–π Interactions

Cited by 18 publications

References 319 publications

Reinterpreting π-stacking

Reinterpreting π-stacking

Geodesic‐Planar Conjugates: Substituted Buckybowls—Synthesis, Photoluminescence and Electrochemistry

Reinterpreting π-Stacking

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