Article

Characterisation of Nanohybrids of Porphyrins with Metallic and Semiconducting Carbon Nanotubes by EPR and Optical Spectroscopy

  1. Sofie Cambré1,
  2. Wim Wenseleers Dr.1,
  3. Jelena Čulin Dr.1,4,
  4. Sabine Van Doorslaer Prof. Dr.2,
  5. Antonio Fonseca Dr.3,
  6. Janos B. Nagy Prof. Dr.3,
  7. Etienne Goovaerts Prof. Dr.1

Article first published online: 19 AUG 2008

DOI: 10.1002/cphc.200800317

Issue

ChemPhysChem

ChemPhysChem

Volume 9, Issue 13, pages 1930–1941, September 15, 2008

Additional Information

How to Cite

Cambré, S., Wenseleers, W., Čulin, J., Van Doorslaer, S., Fonseca, A., Nagy, J. B. and Goovaerts, E. (2008), Characterisation of Nanohybrids of Porphyrins with Metallic and Semiconducting Carbon Nanotubes by EPR and Optical Spectroscopy. ChemPhysChem, 9: 1930–1941. doi: 10.1002/cphc.200800317

Author Information

  1. 1

    Experimental Condensed Matter Physics Laboratory, Department of Physics, University of Antwerp, Universiteitsplein 1, 2610 Antwerp (Belgium), Fax: (+32) 3-8202470

  2. 2

    Spectroscopy in Biophysics and Catalysis Laboratory, Department of Physics, University of Antwerp, Universiteitsplein 1, 2610 Antwerp (Belgium)

  3. 3

    Laboratoire CES, FUNDP, Rue de Bruxelles 61, B-5000 Namur (Belgium)

  4. 4

    Current address: Rudjer Boskovic Institute, Zagreb 1000 (Croatia)

Publication History

  1. Issue published online: 9 SEP 2008
  2. Article first published online: 19 AUG 2008
  3. Manuscript Revised: 7 JUL 2008
  4. Manuscript Received: 27 MAY 2008

Funded by

  • Institute for the Promotion of Innovation through Science and Technology in Flanders
  • Fund for Scientific Research Flanders
  • FWO. Grant Numbers: G.0116.06, G.0129.07

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Keywords:

  • EPR spectroscopy;
  • hybrids;
  • metalloporphyrins;
  • nanotubes;
  • UV/Vis spectroscopy

Graphical Abstract

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Resolving the interations of cobalt(II) porphyrins adsorbed on metallic and semiconducting CNTs is achieved by electron paramagnetic resonance spectroscopy revealing that metallic carbon nanotubes are the strongest acceptors. Absorption spectra (see figure) of the purified nanohybrids show large red-shifts.

Abstract

Single-walled carbon nanotubes (SWCNTs) are noncovalently functionalised with octaethylporphyrins (OEPs) and the resulting nanohybrids are isolated from the free OEPs. Electron paramagnetic resonance (EPR) spectroscopy of cobalt(II)OEP, adsorbed on the nanotube walls by π–π-stacking, demonstrates that the CNTs act as electron acceptors. EPR is shown to be very effective in resolving the different interactions for metallic and semiconducting tubes. Moreover, molecular oxygen is shown to bind selectively to nanohybrids with semiconducting tubes. Water solubilisation of the porphyrin/CNT nanohybrids using bile salts, after applying a thorough washing procedure, yields solutions in which at least 99 % of the porphyrins are interacting with the CNTs. Due to this purification, we observe, for the first time, the isolated absorption spectrum of the interacting porphyrins, which is strongly red-shifted compared to the free porphyrin absorption. In addition a quasi-complete quenching of the porphyrin fluorescence is also observed.

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