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Triple phase boundary photovoltammetry: resolving rhodamine B reactivity in 4-(3-phenylpropyl)-pyridine microdroplets


Reference:

Collins, A. M., Zhang, X. H., Scragg, J. J., Blanchard, G. J. and Marken, F., 2010. Triple phase boundary photovoltammetry: resolving rhodamine B reactivity in 4-(3-phenylpropyl)-pyridine microdroplets. ChemPhysChem, 11 (13), pp. 2862-2870.

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Official URL:

http://dx.doi.org/10.1002/cphc.200000094

Abstract

Rhodamine B base is employed as a photoactive redox system in a liquid I liquid I electrode triple phase boundary electrochemical experiment. Microdroplets of the water-immiscible 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 phosphate buffer solution (pH 12). In cyclic voltammetry experiments, it is shown that dark reduction of rhodamine B to leuco-rhodamine B in PPP occurs in two steps-both one electron processes-and the re-oxidation occurs in a single two-electron process. Voltammetric signals are consistent with Na+ transfer (for the first reduction step) and proton transfer (for the second reduction step) coupled to the electron transfer. A proton-driven disproportionation reaction (with k(dis)=3 mol(-1) dm(3) s(-1) at pH 12) is observed for the one-electron reduced intermediate. In the presence of light, a new photocatalysed oxidation process for the two-electron conversion of leuco-rhodamine B to rhodamine B is observed. Photoexcitation of rhodamine B is shown to trigger an effective photo-comproportionation mechanism. Quantitative insights into the dark and photomechanisms are obtained by comparison of rhodamine B and rhodamine B octadecylester and by applying an approximate numerical simulation procedure based on DigiSim.

Details

Item Type Articles
CreatorsCollins, A. M., Zhang, X. H., Scragg, J. J., Blanchard, G. J. and Marken, F.
DOI10.1002/cphc.200000094
Uncontrolled Keywordsinterfaces, ion transfer, photoelectrochemistry, rhodamine, digisim
DepartmentsFaculty of Science > Chemistry
RefereedYes
StatusPublished
ID Code21293

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