Experimental Support for the Role of Dispersion Forces in Aromatic Interactions

• Type: Article in International Scientific Journal
• Date: 2012

Authors

Carlos F R A C Lima (Author) Other; Marisa A A Rocha (Author) Other; Ligia R Gomes (Author) Other; John N Low (Author) Other; Artur M S Silva (Author) Other; Luis M N B F Santos (Author) FCUP

Journal

Title: Chemistry - A European Journal

Vol. 18

Pages: 8934-8943

ISSN: 0947-6539

Publisher: Wiley-Blackwell

Indexing

ISI Web of Knowledge - 32 Citations

Scopus - 33 Citations

Scientific classification

FOS: Natural sciences > Chemical sciences

Other information

Authenticus ID: P-002-8A3

DOI: 10.1002/chem.201201056

Abstract (EN): Herein a core scaffold of 1-phenylnaphthalenes and 1,8-diphenylnaphthalenes with different substituents on the phenyl rings was used to study substituent effects on parallel-displaced aromatic p...p interactions. The energetics of the interaction was evaluated in gas phase based on the standard molar enthalpies of formation, at T=298.15 K, for the compounds studied; these values were derived from the combination of the results obtained by combustion calorimetry and Knudsen/Quartz crystal effusion. A homodesmotic gas-phase reaction scheme was used to quantify and compare the intramolecular interaction enthalpies in various substituted 1,8-diphenylnaphthalenes. The application of this methodology allowed a direct evaluation of aromatic interactions, and showed that substituent effects on the interaction enthalpy cannot be rationalized solely on classical electrostatic grounds, because no correlation with the smeta or spara Hammett constants was observed. Moreover, the results obtained indicate that aromatic p...p interactions are significantly enhanced by substitution, in a way that correlates with the ability of the interacting aryl rings to establish dispersive interactions. A combined experimental and computational approach for calculation of the true aromatic p...p interaction energies in these systems, free of secondary effects, was employed, and corroborates the rationale derived from the experimental results. These findings clearly emphasize the role of dispersion and dilute the importance of electrostatic forces on this type of interactions.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 10