Abstract

Exploratory 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 oC, 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 oC 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.
Original languageEnglish
JournalJournal of Solid State Electrochemistry
Publication statusAccepted/In press - 13 Nov 2019

Cite this

Voltammetric Monitoring of a Solid-Liquid Phase Transition in N,N,N’,N’-Tetraoctyl-2,6-diamino-9,10-anthraquinone (TODAQ). / Marken, Frank; Jones, Matthew; Ahn, Sun Yhik; Forder, Thomas; Blackburn, Richard; Fordred, Paul; Bull, Steven.

In: Journal of Solid State Electrochemistry, 13.11.2019.

Research output: Contribution to journalArticle

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title = "Voltammetric Monitoring of a Solid-Liquid Phase Transition in N,N,N’,N’-Tetraoctyl-2,6-diamino-9,10-anthraquinone (TODAQ)",
abstract = "Exploratory 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 oC, 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 oC 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.",
author = "Frank Marken and Matthew Jones and Ahn, {Sun Yhik} and Thomas Forder and Richard Blackburn and Paul Fordred and Steven Bull",
year = "2019",
month = "11",
day = "13",
language = "English",
journal = "Journal of Solid State Electrochemistry",
issn = "1432-8488",
publisher = "Springer Verlag",

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TY - JOUR

T1 - Voltammetric Monitoring of a Solid-Liquid Phase Transition in N,N,N’,N’-Tetraoctyl-2,6-diamino-9,10-anthraquinone (TODAQ)

AU - Marken, Frank

AU - Jones, Matthew

AU - Ahn, Sun Yhik

AU - Forder, Thomas

AU - Blackburn, Richard

AU - Fordred, Paul

AU - Bull, Steven

PY - 2019/11/13

Y1 - 2019/11/13

N2 - Exploratory 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 oC, 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 oC 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.

AB - Exploratory 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 oC, 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 oC 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.

M3 - Article

JO - Journal of Solid State Electrochemistry

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