High Pressure Studies on the Planarity of Para-hexaphenyl

Abstract

We present experimental and theoretical findings on the geometry of para-hexaphenyl (PHP) molecules in polycrystalline powder. A new method to assess the planarity of PHP via Raman spectroscopy is presented. Based on this method we describe a W-shaped potential energy curve which governs the torsional motion between neighboring phenyl rings. We determine the activation energy to promote PHP from a non-planar to a planar state to be 0.04 eV, in good agreement with our quantum chemical calculations. Finally we are able to experimentally planarize the molecules by the application of hydrostatic pressure, which modifies the W-shaped potential energy curve to a U-shaped one.

Department(s)

Chemistry

Sponsor(s)

Conseil Regional du Languedoc-Roussillon
District de Montpellier
Ministere de l'Education Nationale
Universite de Montpellier II

Keywords and Phrases

Activation energy; Electron energy levels; High pressure effects; Molecular structure; Probability density function; Quantum theory; Raman spectroscopy; Activation energy; Hydrostatic pressure; Molecular dynamics; Polycrystalline materials; Potential energy; Quantum theory; Raman spectroscopy; Density functional calculations; Para hexaphenyl; Phenyl rings; Quantum chemical calculations; Semiconducting organic compounds; Semiconducting organic compounds; Density functional theory; Parahexaphenyl

International Standard Serial Number (ISSN)

0379-6779

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 1999 Elsevier Sequoia SA, Lausanne, All rights reserved.

Publication Date

01 May 1999

Link to Full Text

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