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The crystalline structure of the phenazine overlayer physisorbed on a graphite surface


Type

Article

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Authors

Brewer, AY 
Sacchi, M 
Parker, JE 
Truscott, CL 
Jenkins, SJ 

Abstract

The monolayer crystal structure of phenazine adsorbed on graphite is determined by a combination of synchrotron X-ray diffraction and DFT calculations. The molecules adopt a rectangular unit cell with lattice parameters a = 13.55 Å and b = 10.55 Å, which contains 2 molecules. The plane group of the unit cell is p2gg, and each molecule is essentially flat to the plane of the surface, with only a small amount of out-of-plane tilt. Density Functional Theory (DFT) calculations find a minimum energy structure with a unit cell which agrees within 7.5% with that deduced by diffraction. DFT including dispersion force corrections (DFT+D) calculations help to identify the nature of the intermolecular bonding. The overlayer interactions are principally van der Waals, with a smaller contribution from weak C-H•••N hydrogen bonds. This behaviour is compared with that of 4,4’-bipyridyl.

Description

Keywords

monolayer, physisorption, synchrotron, DFT, phenazine

Journal Title

Molecular Physics

Conference Name

Journal ISSN

0026-8976
1362-3028

Volume Title

111

Publisher

Informa UK Limited
Sponsorship
Engineering and Physical Sciences Research Council (EP/J001643/1)
We acknowledge financial support for AB from an EPSRC DTA award from the Department of Chemistry, University of Cambridge; and BP for financial support for CT. We thank Diamond Light Source for access to beamline I11 (EE7761) that contributed to the results presented here. The DFT calculations were performed using the Darwin Supercomputer of the University of Cambridge High Performance Computing Service.