Advanced search
1 file | 619.23 KB Add to list

Self assembled films of porphyrins with amine groups at different positions : influence of their orientation on the corrosion inhibition and the electrocatalytic activity

(2012) MOLECULES. 17(7). p.7824-7842
Author
Organization
Abstract
Self-assembled molecular films of two cobalt porphyrins with amine groups at different positions-(5,10,15,20-tetrakis-(2-aminophenyl) porphyrin-cobalt(II), [Co(II) (T(o-NH2)PP)] and (5,10,15,20-tetrakis-(4-aminophenyl) porphyrin-cobalt(II), [Co(II)(T(p-NH2)PP)]-were formed on a gold substrate. The functionalized surfaces were characterized using Raman spectroscopy, atomic force microscopy and electrochemical methods. Both modified gold surfaces completely mask the charge transfer of a [Fe(CN)(6)](3-/4-) redox couple in solution, indicating the layer is highly resistive in behavior. Electrochemical impedance spectroscopy analyses revealed that the porphyrin film with amine groups at ortho positions shows a higher charge-transfer resistance with a better protective behavior compared to the para position modified surface. Raman, AFM and EIS data suggests that an ortho amine positioned molecule forms a more compact layer compared to the para-positioned molecule. This can be explained in terms of their orientation on the gold surface. [Co(II)(T(o-NH2) PP)] adopted a saddle shape orientation whereas [Co(II)(T(p-NH2) PP)] adopted a flat orientation on the gold surface. The porphyrin modified gold electrode catalyzes the oxygen reduction at lower potentials compared to the bare gold electrode. The shift in the overvoltage was higher in case of molecules with flat orientation compared to the saddle shaped oriented porphyrin molecules on the surface.
Keywords
self assembly, porphyrin, electrocatalysis, orientation, ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY, LANGMUIR-BLODGETT-FILMS, GOLD ELECTRODES, NICOTINAMIDE COENZYMES, IRON PHTHALOCYANINE, GRAPHITE-ELECTRODES, MONOMOLECULAR FILMS, HYDROGEN-PEROXIDE, AU(111) SURFACE, MOLECULAR FILMS

Downloads

  • MoleculesLokesh2012.pdf
    • full text
    • |
    • open access
    • |
    • PDF
    • |
    • 619.23 KB

Citation

Please use this url to cite or link to this publication:

MLA
Lokesh, Koodlur, et al. “Self Assembled Films of Porphyrins with Amine Groups at Different Positions : Influence of Their Orientation on the Corrosion Inhibition and the Electrocatalytic Activity.” MOLECULES, vol. 17, no. 7, 2012, pp. 7824–42.
APA
Lokesh, K., De Keersmaecker, M., & Adriaens, M. (2012). Self assembled films of porphyrins with amine groups at different positions : influence of their orientation on the corrosion inhibition and the electrocatalytic activity. MOLECULES, 17(7), 7824–7842.
Chicago author-date
Lokesh, Koodlur, Michel De Keersmaecker, and Mieke Adriaens. 2012. “Self Assembled Films of Porphyrins with Amine Groups at Different Positions : Influence of Their Orientation on the Corrosion Inhibition and the Electrocatalytic Activity.” MOLECULES 17 (7): 7824–42.
Chicago author-date (all authors)
Lokesh, Koodlur, Michel De Keersmaecker, and Mieke Adriaens. 2012. “Self Assembled Films of Porphyrins with Amine Groups at Different Positions : Influence of Their Orientation on the Corrosion Inhibition and the Electrocatalytic Activity.” MOLECULES 17 (7): 7824–7842.
Vancouver
1.
Lokesh K, De Keersmaecker M, Adriaens M. Self assembled films of porphyrins with amine groups at different positions : influence of their orientation on the corrosion inhibition and the electrocatalytic activity. MOLECULES. 2012;17(7):7824–42.
IEEE
[1]
K. Lokesh, M. De Keersmaecker, and M. Adriaens, “Self assembled films of porphyrins with amine groups at different positions : influence of their orientation on the corrosion inhibition and the electrocatalytic activity,” MOLECULES, vol. 17, no. 7, pp. 7824–7842, 2012.
@article{3097466,
  abstract     = {Self-assembled molecular films of two cobalt porphyrins with amine groups at different positions-(5,10,15,20-tetrakis-(2-aminophenyl) porphyrin-cobalt(II), [Co(II) (T(o-NH2)PP)] and (5,10,15,20-tetrakis-(4-aminophenyl) porphyrin-cobalt(II), [Co(II)(T(p-NH2)PP)]-were formed on a gold substrate. The functionalized surfaces were characterized using Raman spectroscopy, atomic force microscopy and electrochemical methods. Both modified gold surfaces completely mask the charge transfer of a [Fe(CN)(6)](3-/4-) redox couple in solution, indicating the layer is highly resistive in behavior. Electrochemical impedance spectroscopy analyses revealed that the porphyrin film with amine groups at ortho positions shows a higher charge-transfer resistance with a better protective behavior compared to the para position modified surface. Raman, AFM and EIS data suggests that an ortho amine positioned molecule forms a more compact layer compared to the para-positioned molecule. This can be explained in terms of their orientation on the gold surface. [Co(II)(T(o-NH2) PP)] adopted a saddle shape orientation whereas [Co(II)(T(p-NH2) PP)] adopted a flat orientation on the gold surface. The porphyrin modified gold electrode catalyzes the oxygen reduction at lower potentials compared to the bare gold electrode. The shift in the overvoltage was higher in case of molecules with flat orientation compared to the saddle shaped oriented porphyrin molecules on the surface.},
  author       = {Lokesh, Koodlur and De Keersmaecker, Michel and Adriaens, Mieke},
  issn         = {1420-3049},
  journal      = {MOLECULES},
  keywords     = {self assembly,porphyrin,electrocatalysis,orientation,ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY,LANGMUIR-BLODGETT-FILMS,GOLD ELECTRODES,NICOTINAMIDE COENZYMES,IRON PHTHALOCYANINE,GRAPHITE-ELECTRODES,MONOMOLECULAR FILMS,HYDROGEN-PEROXIDE,AU(111) SURFACE,MOLECULAR FILMS},
  language     = {eng},
  number       = {7},
  pages        = {7824--7842},
  title        = {Self assembled films of porphyrins with amine groups at different positions : influence of their orientation on the corrosion inhibition and the electrocatalytic activity},
  url          = {http://dx.doi.org/10.3390/molecules17077824},
  volume       = {17},
  year         = {2012},
}

Altmetric
View in Altmetric
Web of Science
Times cited: