Triple Phase Boundary Photo-Voltammetry: Resolving Rhodamine B Reactivity in 4-(3-Phenylpropyl)-Pyridine Microdroplets

Andrew Collins 1Xiaohang Zhang 1Laurie M. Peter 1Jonathon J. Scragg 1Gary J. Blanchard 2Frank Marken 1

1. University of Bath, Department of Chemistry, Claverton Down, Bath BA2-7AY, United Kingdom
2. Michigan State University, Department of Chemistry (MSU), East Lansing, MI 48824, United States

Abstract

The Rhodamine B base is employed as a redox system in a liquid|liquid electrochemical system. Microdroplets of 3-(4-phenylpropyl)-pyridine (PPP) containing Rhodamine B are deposited onto a basal plane pyrolytic graphite electrode surface which is then immersed into an aqueous solution containing 0.5 M pH=12 phosphate buffer solution. In cyclic voltammetry experiments conducted in the dark it is shown that reduction of Rhodamine B to leuco-Rhodamine occurs in two steps, both are one-electron processes, and re-oxidation occurs in a single two-electron process. For the first reduction, voltammetric signals are consistent with the Na+ transfer coupled with the electron transfer, whilst for the second reduction the signals are consistent with a one-electron one-proton transfer. A chemical step occurs in the form of a proton driven disproportionation for the one-electron reduced species. This process has been shown to have a kdis= 3 mol-1 dm-3 s-1.

The presence of light facilitates a photocatalytic oxidation process which occurs in place of the two-electron oxidation observed in the dark scans. A conproportionation is triggered by the photo-activation of Rhodamine B, (kcon = 0.7/[Rhodamine B*] s-1 at pH=12 where [Rhodamine B*] denotes steady-state concentration of the photoexcited state). Quantitative insights into the dark and photo-mechanisms are obtained by comparison behaviour of Rhodamine B and Rhodamine B octadecylester and by applying numerical simulation using DigiSim.

Collins_figure_1.png

Figure 1. Comparison of the photocatalysed oxidation (black) and dark (green) voltammogram for the Rhodamine B base at 0.01 V/s-1; 16 nl deposit, 0.28 M (Rhodamine B : PPP).

 

Related papers
  1. Impedance Methods in Electrochemistry
  2. Redox Reactivity of Methylene Blue in the Pores of UMCM-1 Metal-Organic Frameworks
  3. Carbon Nanoparticle Surface Modification for Sensor Development
  4. Organization and Dynamics within Supported Interfaces:  Implications for the Creation of Biomimetic Structures
  5. Ion Association Effects in Cellulose – Poly-(Diallyldimethylammonium) Reassembled Membranes Immersed in Acetonitrile
  6. Conduction in Nanoparticle Assemblies and Mesoporous Films
  7. Positively Charged Surface Functionalised Carbon Nanoparticles as Binding Sites for Redox Active Species
  8. Carbon Dioxide Sensing Systems Based On Processes At Triple Phase Boundary Interfaces
  9. Strategies for Self-Assembly of Phospholipids at Interfaces
  10. Electrochemical behaviour of carbonised cellulose nanofibril films on the ITO electrode surface
  11. MoSe2 Substrates for the Electrodeposition of CISe Semiconductor Films
  12. Silver Nanoparticle Catalysed NO3- Reduction Characterised with a Hydrodynamic Generator-Collector SPCE System
  13. Determination of Dopamine in Presence of Ascorbate in Ultrathin Carbon Nanoparticle Composite Film Electrodes
  14. Driving ion transfer across the toluene (trihexyl(tetradecyl)-phosphonium tris(pentafluoroethyl)trifluoro-phosphate) | water (electrolyte) interface with the MnTPP(III/II) redox system
  15. Understanding and Controlling Curvature and Intermolecular Interactions in Biomimetic Membranes
  16. Probing interfacial organization in planar lipid bilayers using tethered pyrene
  17. Immobilization of molecules: From self-assembled monolayers to polymeric hollow structures
  18. Electrocatalytic Sulphite Detection at a Liquid-Liquid-Solid Three-Phase Boundary Electrode Sensors
  19. Electrochemical Processes at Electrodes in Microwave Fields
  20. Liquid-Liquid Ion-Transfer Electrochemistry at Stationary and at Flowing Triple Phase Boundaries
  21. Microwave-assisted Capillary Electrophoresis with Electrochemical Detection
  22. Analysis of Chlorobenzenes in Environmental Water Samples using Microwave-Assisted with Ionic-Liquids Liquid-Phase Microextraction
  23. Electrochemical reactivity of proteins immobilised in mesoporous titania
  24. New electrode surfaces for solid | liquid | liquid triple phase boundary electrochemistry
  25. Probing organization and communication at layered interfaces
  26. Ion transfer electrodes based on carbon nanofibers embedded in silicate film modified with room temperature ionic liquid
  27. Nanoobjects embedded in silicate films for biphasic electrodes
  28. Electrochemical Processes in Mesoporous TiO2 Phytate Films
  29. Design, Synthesis and Characterization of Monomolecular Interfacial Layers

Presentation: Short communication at SMCBS'2009 International Workshop, by Andrew Collins
See On-line Journal of SMCBS'2009 International Workshop

Submitted: 2009-09-03 20:41
Revised:   2009-09-09 18:10