Hexakis(2,3,6-tri-: O -methyl)-α-cyclodextrin-I5- complex in aqueous I-/I3- thermocells and enhancement in the Seebeck coefficient

Yimin Liang; Teppei Yamada; Hongyao Zhou; Nobuo Kimizuka

doi:10.1039/c8sc03821j

Hexakis(2,3,6-tri-: O -methyl)-α-cyclodextrin-I₅^- complex in aqueous I^-/I₃^- thermocells and enhancement in the Seebeck coefficient

Yimin Liang, Teppei Yamada, Hongyao Zhou, Nobuo Kimizuka

Applied Chemistry

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20 Citations (Scopus)

Abstract

A large Seebeck coefficient (S_e) of 1.9 mV K^-1 was recorded for the I^-/I₃^- thermocell by utilizing the host-guest complexation of hexakis(2,3,6-tri-O-methyl)-α-cyclodextrin (Me₁₈-α-CD) with the oxidized iodide species. The thermocell measurement and UV-vis spectroscopy unveiled the formation of an Me₁₈-α-CD-pentaiodide (I₅^-) complex, which is in remarkable contrast to the triiodide complex α-CD-I₃^- previously reported. Although the precipitation of the α-CD-I₃^- complex in the presence of an electrolyte such as potassium chloride is a problem in thermocells, this issue was solved by using Me₁₈-α-CD as a host compound. The absence of precipitation in the Me₁₈-α-CD and I^-/I₃^- system containing potassium chloride not only improved the S_e of the I^-/I₃^- thermocell, but also significantly enhanced the temporal stability of its power output. This is the first observation that I₅^- species is formed in aqueous solution in a thermocell. Furthermore, the solution equilibrium of the redox couples was controlled by tuning the chemical structure of the host compounds. Thus, the integration of host-guest chemistry with redox couples extends the application of thermocells.

Original language	English
Pages (from-to)	773-780
Number of pages	8
Journal	Chemical Science
Volume	10
Issue number	3
DOIs	https://doi.org/10.1039/c8sc03821j
Publication status	Published - 2019

All Science Journal Classification (ASJC) codes

Chemistry(all)

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10.1039/c8sc03821j

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title = "Hexakis(2,3,6-tri-: O -methyl)-α-cyclodextrin-I5- complex in aqueous I-/I3- thermocells and enhancement in the Seebeck coefficient",

abstract = "A large Seebeck coefficient (Se) of 1.9 mV K-1 was recorded for the I-/I3- thermocell by utilizing the host-guest complexation of hexakis(2,3,6-tri-O-methyl)-α-cyclodextrin (Me18-α-CD) with the oxidized iodide species. The thermocell measurement and UV-vis spectroscopy unveiled the formation of an Me18-α-CD-pentaiodide (I5-) complex, which is in remarkable contrast to the triiodide complex α-CD-I3- previously reported. Although the precipitation of the α-CD-I3- complex in the presence of an electrolyte such as potassium chloride is a problem in thermocells, this issue was solved by using Me18-α-CD as a host compound. The absence of precipitation in the Me18-α-CD and I-/I3- system containing potassium chloride not only improved the Se of the I-/I3- thermocell, but also significantly enhanced the temporal stability of its power output. This is the first observation that I5- species is formed in aqueous solution in a thermocell. Furthermore, the solution equilibrium of the redox couples was controlled by tuning the chemical structure of the host compounds. Thus, the integration of host-guest chemistry with redox couples extends the application of thermocells.",

author = "Yimin Liang and Teppei Yamada and Hongyao Zhou and Nobuo Kimizuka",

note = "Funding Information: This study was partly supported by JST PRESTO Grant Number JPMJPR141D, Japan and JSPS KAKENHI Grant Numbers JP25220805, JP17H03046, JP26708007 and JP16H06513 (Coordination Asymmetry). The authors gratefully acknowledge the support of ITC measurement from Dr Yu Hoshino (Department of Chemical Engineering, Graduate School of Engineering, Kyushu University). Publisher Copyright: {\textcopyright} 2019 The Royal Society of Chemistry.",

year = "2019",

doi = "10.1039/c8sc03821j",

language = "English",

volume = "10",

pages = "773--780",

journal = "Chemical Science",

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T2 - O -methyl)-α-cyclodextrin-I5- complex in aqueous I-/I3- thermocells and enhancement in the Seebeck coefficient

AU - Liang, Yimin

AU - Yamada, Teppei

AU - Zhou, Hongyao

AU - Kimizuka, Nobuo

N1 - Funding Information: This study was partly supported by JST PRESTO Grant Number JPMJPR141D, Japan and JSPS KAKENHI Grant Numbers JP25220805, JP17H03046, JP26708007 and JP16H06513 (Coordination Asymmetry). The authors gratefully acknowledge the support of ITC measurement from Dr Yu Hoshino (Department of Chemical Engineering, Graduate School of Engineering, Kyushu University). Publisher Copyright: © 2019 The Royal Society of Chemistry.

PY - 2019

Y1 - 2019

N2 - A large Seebeck coefficient (Se) of 1.9 mV K-1 was recorded for the I-/I3- thermocell by utilizing the host-guest complexation of hexakis(2,3,6-tri-O-methyl)-α-cyclodextrin (Me18-α-CD) with the oxidized iodide species. The thermocell measurement and UV-vis spectroscopy unveiled the formation of an Me18-α-CD-pentaiodide (I5-) complex, which is in remarkable contrast to the triiodide complex α-CD-I3- previously reported. Although the precipitation of the α-CD-I3- complex in the presence of an electrolyte such as potassium chloride is a problem in thermocells, this issue was solved by using Me18-α-CD as a host compound. The absence of precipitation in the Me18-α-CD and I-/I3- system containing potassium chloride not only improved the Se of the I-/I3- thermocell, but also significantly enhanced the temporal stability of its power output. This is the first observation that I5- species is formed in aqueous solution in a thermocell. Furthermore, the solution equilibrium of the redox couples was controlled by tuning the chemical structure of the host compounds. Thus, the integration of host-guest chemistry with redox couples extends the application of thermocells.

AB - A large Seebeck coefficient (Se) of 1.9 mV K-1 was recorded for the I-/I3- thermocell by utilizing the host-guest complexation of hexakis(2,3,6-tri-O-methyl)-α-cyclodextrin (Me18-α-CD) with the oxidized iodide species. The thermocell measurement and UV-vis spectroscopy unveiled the formation of an Me18-α-CD-pentaiodide (I5-) complex, which is in remarkable contrast to the triiodide complex α-CD-I3- previously reported. Although the precipitation of the α-CD-I3- complex in the presence of an electrolyte such as potassium chloride is a problem in thermocells, this issue was solved by using Me18-α-CD as a host compound. The absence of precipitation in the Me18-α-CD and I-/I3- system containing potassium chloride not only improved the Se of the I-/I3- thermocell, but also significantly enhanced the temporal stability of its power output. This is the first observation that I5- species is formed in aqueous solution in a thermocell. Furthermore, the solution equilibrium of the redox couples was controlled by tuning the chemical structure of the host compounds. Thus, the integration of host-guest chemistry with redox couples extends the application of thermocells.

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Hexakis(2,3,6-tri-: O -methyl)-α-cyclodextrin-I₅^- complex in aqueous I^-/I₃^- thermocells and enhancement in the Seebeck coefficient

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