Voltammetric monitoring of a solid-liquid phase transition in N,N,N′,N′-tetraoctyl-2,6-diamino-9,10-anthraquinone (TODAQ)
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Published:2019-11-25
Issue:1
Volume:24
Page:11-16
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ISSN:1432-8488
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Container-title:Journal of Solid State Electrochemistry
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language:en
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Short-container-title:J Solid State Electrochem
Author:
Ahn Sunyhik,
Forder Thomas R.,
Jones Matthew D.,
Blackburn Richard A. R.,
Fordred Paul S.,
Bull Steven D.,
Marken FrankORCID
Abstract
AbstractExploratory experiments on effects from a phase transition are reported for a low-melting microcrystalline anthraquinone (N,N,N′,N′-tetraoctyl-2,6-diamino-9,10-anthraquinone or TODAQ). Data for the solid-liquid phase transition are obtained by differential scanning calorimetry and then compared to data obtained by voltammetry. In preliminary electrochemical measurements, microcrystal deposits on a basal plane pyrolytic graphite electrode are shown to undergo a solid-state 2-electron 2-proton reduction in contact to aqueous 0.1 M HClO4 with a midpoint potential Emid,solid = − 0.24 V vs. SCE. The reduction mechanism is proposed to be limited mainly by the triple phase boundary line and some transport of TODAQ molecules towards the electrode surface for both solid and melt. A change in the apparent activation energy for this reduction is observed at 69 °C, leading to an enhanced increase in reduction current with midpoint potential Emid,liquid = − 0.36 V vs. SCE. A change of TODAQ transport along the crystal surface for solid microcrystalline material (for the solid) to diffusion within molten microdroplets (for the liquid) is proposed. Upon cooling, a transition at 60 °C back to a higher apparent activation energy is seen consistent with re-solidification of the molten phase at the electrode surface. Differential scanning calorimetry data for solid TODAQ dry and for TODAQ in contact to aqueous 0.1 M HClO4 confirm these transitions.
Funder
Engineering and Physical Sciences Research Council
Publisher
Springer Science and Business Media LLC
Subject
Electrical and Electronic Engineering,Electrochemistry,Condensed Matter Physics,General Materials Science
Reference39 articles.
1. Scholz F, Meyer B (1998) Electroanal Chem 20:1–86
2. Schröder U, Compton RG, Marken F, Bull SD, Davies SG, Gilmour S, Phys J (2001) Chem B 105:1344–1350
3. Scholz F, Schröder U, Gulaboski R (2005) Electrochemistry of immobilized particles and droplets. Springer, Berlin
4. Grygar T, Marken F, Schröder U, Scholz F (2002) Coll Czech Chem Commun 67:163–208
5. Domenech-Carbo A, Domenech-Carbo MT, Calisti M, Maiolo V (2010) Talanta 81:404–411