Orbital-resolved partial charge transfer from the methoxy groups of substituted pyrenes in complexes with tetracyanoquinodimethane - A NEXAFS study

Katerina Medjanik, Dennis Chercka, Peter Nagel, Michael Merz, Stefan Schuppler, Martin Baumgarten, Klaus Müllen, Sergej A. Nepijko, Hans Joachim Elmers, Gerd Schönhense, Harald Olaf Jeschke, Roser Valenti

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

It is demonstrated that the near-edge X-ray absorption fine structure (NEXAFS) provides a powerful local probe of functional groups in novel charge transfer (CT) compounds and their electronic properties. Microcrystals of tetra-/hexamethoxypyrene as donors with the strong acceptor tetracyano-p- quinodimethane (TMP/HMP-TCNQ) were grown by vapor diffusion. The oxygen and nitrogen K-edge spectra are spectroscopic fingerprints of the functional groups in the donor and acceptor moieties, respectively. The orbital selectivity of the NEXAFS pre-edge resonances allows us to precisely elucidate the participation of specific orbitals in the charge transfer process. Upon complex formation, the intensities of several resonances change substantially and a new resonance occurs in the oxygen K-edge spectrum. This gives evidence of a corresponding change of hybridization of specific orbitals in the functional groups of the donor (those derived from the frontier orbitals 2e and 6a 1 of the isolated methoxy group) and acceptor (orbitals b 3g, a u, b 1g, and b 2u, all located at the cyano group) with π*-orbitals of the ring systems. Along with this intensity effect, the resonance positions associated with the oxygen K-edge (donor) and nitrogen K-edge (acceptor) shift to higher and lower photon energies in the complex, respectively. A calculation based on density functional theory qualitatively explains the experimental results. NEXAFS measurements shine light on the action of the functional groups and elucidate charge transfer on a submolecular level.

Original languageEnglish
Pages (from-to)4694-4699
Number of pages6
JournalJournal of the American Chemical Society
Volume134
Issue number10
DOIs
Publication statusPublished - Mar 14 2012
Externally publishedYes

Fingerprint

Pyrenes
Pyrene
X ray absorption
Functional groups
Charge transfer
X-Rays
Oxygen
Nitrogen
Thymidine Monophosphate
Light measurement
Dermatoglyphics
Photons
Microcrystals
Electronic properties
Density functional theory
Vapors
tetracyanoquinodimethane

ASJC Scopus subject areas

  • Chemistry(all)
  • Catalysis
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Orbital-resolved partial charge transfer from the methoxy groups of substituted pyrenes in complexes with tetracyanoquinodimethane - A NEXAFS study. / Medjanik, Katerina; Chercka, Dennis; Nagel, Peter; Merz, Michael; Schuppler, Stefan; Baumgarten, Martin; Müllen, Klaus; Nepijko, Sergej A.; Elmers, Hans Joachim; Schönhense, Gerd; Jeschke, Harald Olaf; Valenti, Roser.

In: Journal of the American Chemical Society, Vol. 134, No. 10, 14.03.2012, p. 4694-4699.

Research output: Contribution to journalArticle

Medjanik, K, Chercka, D, Nagel, P, Merz, M, Schuppler, S, Baumgarten, M, Müllen, K, Nepijko, SA, Elmers, HJ, Schönhense, G, Jeschke, HO & Valenti, R 2012, 'Orbital-resolved partial charge transfer from the methoxy groups of substituted pyrenes in complexes with tetracyanoquinodimethane - A NEXAFS study', Journal of the American Chemical Society, vol. 134, no. 10, pp. 4694-4699. https://doi.org/10.1021/ja2100802
Medjanik, Katerina ; Chercka, Dennis ; Nagel, Peter ; Merz, Michael ; Schuppler, Stefan ; Baumgarten, Martin ; Müllen, Klaus ; Nepijko, Sergej A. ; Elmers, Hans Joachim ; Schönhense, Gerd ; Jeschke, Harald Olaf ; Valenti, Roser. / Orbital-resolved partial charge transfer from the methoxy groups of substituted pyrenes in complexes with tetracyanoquinodimethane - A NEXAFS study. In: Journal of the American Chemical Society. 2012 ; Vol. 134, No. 10. pp. 4694-4699.
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