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Electrochemical Studies of Redox Properties and Diffusion in Self-Assembled Systems
Uppsala universitet, Fysikalisk-kemiska institutionen.ORCID iD: 0000-0002-3140-7378
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis electron transfer reactions and diffusion of redox molecules in three different types of self-aggregated structures are investigated. Electrochemistry was used to investigate the redox potential and diffusion coefficients for redox active molecules with different polarity. The first aggregate system studied was the micellar phase. The role of electrostatic interactions in the stability of an amphiphilic viologen was investigated for differently charged micelles. It was concluded that the electrostatic environment changed the redox potential of the viologen. In differently charged micelles the redox potential was more negative compared to when the viologen was situated in micelles with the same charge.

The second structure investigated is a very fascinating phase, the bicontinuous cubic phase, with its continuous channels of water and an apolar bilayer. Its domains with different polarity made it possible to solvate both hydrophilic and hydrophobic molecules. An amphiphilic molecule will have its head-group at the interface between the apolar and polar part, and can move lateral within the bilayer. All molecules investigated made contact with and reacted at the surface of the electrode. The diffusion of water bound species diffusing in the water channels was 3-4 times slower than in water. Hydrophobic and amphiphilic molecules were much more hindered, probably because the cubic phase was not defect free.

The third kind of structure studied was a lamellar system. This phase is built up from planar bilayers that are stacked with a repeating distance and with water in between. A hydrophilic molecule was severely hindered to move in the direction perpendicular to the bilayer plane. Upon addition of the peptide melittin the current increased, due to pore formation in the bilayer.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis , 2004. , p. 69
Keywords [en]
Physical chemistry, electrochemistry, self-assembly, bicontinuos cubic phase, redox potential, diffusion
Keywords [sv]
Fysikalisk kemi
National Category
Physical Chemistry
Identifiers
URN: urn:nbn:se:du-31581ISBN: 91-554-6059-3 (print)OAI: oai:DiVA.org:du-31581DiVA, id: diva2:1382209
Public defence
2004-10-29, B22, BMC, Husargatan 3, 10:15
Opponent
Supervisors
Available from: 2020-01-02 Created: 2020-01-02 Last updated: 2020-01-02Bibliographically approved
List of papers
1. Electrochemical properties of an amphiphilic viologen in differently charged micelles
Open this publication in new window or tab >>Electrochemical properties of an amphiphilic viologen in differently charged micelles
2002 (English)In: Journal of Electroanalytical Chemistry, ISSN 0022-0728, E-ISSN 1873-2569, Vol. 536, no 1-2, p. 97-107Article in journal (Refereed) Published
Abstract [en]

The electrochemical properties of N-tetradecyl-N′-methylviologen (TMV) in differently charged micelles were studied with a glassy carbon electrode using electrochemical techniques. The redox potential varied depending on the charge of the surrounding surfactants. When the viologen was situated in cationic micelles the redox potential for the 2+/1+ reaction was more positive than when situated in negatively charged micelles. The non-ionic micelles destabilised the 2+-state most showing the highest redox potentials. From studies of several different cationic micelles it was concluded that the most important parameter for the redox potential was the surface charge density. A calculation based on a simple model confirmed this. Other interactions also influenced the stability of the redox states. Adsorption, desorption and reorganisation of the surfactants at the electrode surface caused capacitive currents. To control the nonfaradaic current, differential pulse voltammetry (DPV) was used in addition to cyclic voltammetry.

Place, publisher, year, edition, pages
Elsevier, 2002
Keywords
DPV, micelle, electrochemistry, redox potential, amphiphilic viologen
National Category
Physical Chemistry
Identifiers
urn:nbn:se:du-16205 (URN)10.1016/S0022-0728(02)01208-1 (DOI)
Available from: 2014-10-16 Created: 2014-10-16 Last updated: 2020-01-02Bibliographically approved
2. Electrochemistry and diffusion of a redox active surfactant in bicontinuous cubic and lamellar phase
Open this publication in new window or tab >>Electrochemistry and diffusion of a redox active surfactant in bicontinuous cubic and lamellar phase
2005 (English)In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 50, no 16-17, p. 3333-3340Article in journal (Refereed) Published
National Category
Physical Chemistry
Identifiers
urn:nbn:se:du-31583 (URN)
Available from: 2004-10-08 Created: 2020-01-02 Last updated: 2020-01-02Bibliographically approved
3. Redox activity and diffusion of hydrophilic, hydrophobic, and amphiphilic redox active molecules in a bicontinuous cubic phase
Open this publication in new window or tab >>Redox activity and diffusion of hydrophilic, hydrophobic, and amphiphilic redox active molecules in a bicontinuous cubic phase
2005 (English)In: The Journal of Physical Chemistry. B, ISSN 1520-6106, Vol. 109, no 11, p. 5073-Article in journal (Refereed) Published
National Category
Natural Sciences Physical Chemistry Physical Chemistry
Identifiers
urn:nbn:se:du-26971 (URN)
Available from: 2018-01-25 Created: 2018-01-25 Last updated: 2020-01-02Bibliographically approved
4. Electrochemical behaviour of an amphiphilic viologen incorporated in a stacked bilayer system
Open this publication in new window or tab >>Electrochemical behaviour of an amphiphilic viologen incorporated in a stacked bilayer system
(English)In: Journal of Electroanalytical Chemistry, ISSN 0022-0728, E-ISSN 1873-2569Article in journal (Refereed) Submitted
National Category
Physical Chemistry
Identifiers
urn:nbn:se:du-31585 (URN)
Available from: 2004-10-08 Created: 2020-01-02 Last updated: 2020-01-02Bibliographically approved
5. Pore formation in a stacked bilayer system induced by the addition of the peptide melittin
Open this publication in new window or tab >>Pore formation in a stacked bilayer system induced by the addition of the peptide melittin
(English)Manuscript (preprint) (Other academic)
National Category
Physical Chemistry
Identifiers
urn:nbn:se:du-31586 (URN)
Available from: 2004-10-08 Created: 2020-01-02 Last updated: 2020-01-02Bibliographically approved

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Kostela, Johan

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