Unexpected Promotional Effects of Alkyl-Tailed Ligands and Anions on the Electrochemical Generation of Ruthenium(IV)-Oxo Complexes

Chui Shan Tsang; Lawrence Yoon Suk Lee; Kwong Chak Cheung; Pak Ho Chan; Wing Leung Wong; Kwok Yin Wong

doi:10.1002/celc.202100364

Unexpected Promotional Effects of Alkyl-Tailed Ligands and Anions on the Electrochemical Generation of Ruthenium(IV)-Oxo Complexes

Chui Shan Tsang, Lawrence Yoon Suk Lee, Kwong Chak Cheung, Pak Ho Chan, Wing Leung Wong, Kwok Yin Wong (Corresponding Author)

Research output: Journal article publication › Journal article › Academic research › peer-review

Abstract

Electro-generation of Ru^IV=O species from the Ru^II-aqua complex is a crucial step to excel the electrocatalytic water oxidation performance of ruthenium oxo complexes. We report herein the synthesis and X-ray crystal structural characterizations of new Ru^II-aqua complexes containing N-substituted 2,2′-dipyridylamine ligands (L) tagged with an alkyl chain of various lengths, [Ru(tpy)(L)(OH₂)]²⁺. Cyclic voltammetric analyses show that the length of the alkyl chain exerts great influence on the electro-generation of Ru^IV=O species. The L with a longer alkyl chain in an acidic aqueous medium promotes the conversion of Ru^III−OH to Ru^IV=O efficiently. Surprisingly, this conversion can be further enhanced by the presence of perchlorate anions. Chronocoulometric data reveal that the alkyl chain on L promotes the adsorption of the ruthenium complex on the electrode surface. Bulk electrolysis results indicate that the [Ru(tpy)(dppa)(OH₂)]²⁺ (dppa=(2,2′-dipyridyl)-n-propylamine) gives the most active electrocatalytic water oxidation activity among the ruthenium-aqua complexes investigated in this study.

Original language	English
Pages (from-to)	2221-2230
Number of pages	10
Journal	ChemElectroChem
Volume	8
Issue number	12
DOIs	https://doi.org/10.1002/celc.202100364
Publication status	Published - 14 Jun 2021

Keywords

coordination chemistry
electrocatalysis
pyridyl ligand
ruthenium(IV)-oxo complexes
water oxidation

ASJC Scopus subject areas

Catalysis
Electrochemistry

More information

10.1002/celc.202100364

http://hdl.handle.net/10397/91198

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title = "Unexpected Promotional Effects of Alkyl-Tailed Ligands and Anions on the Electrochemical Generation of Ruthenium(IV)-Oxo Complexes",

abstract = "Electro-generation of RuIV=O species from the RuII-aqua complex is a crucial step to excel the electrocatalytic water oxidation performance of ruthenium oxo complexes. We report herein the synthesis and X-ray crystal structural characterizations of new RuII-aqua complexes containing N-substituted 2,2′-dipyridylamine ligands (L) tagged with an alkyl chain of various lengths, [Ru(tpy)(L)(OH2)]2+. Cyclic voltammetric analyses show that the length of the alkyl chain exerts great influence on the electro-generation of RuIV=O species. The L with a longer alkyl chain in an acidic aqueous medium promotes the conversion of RuIII−OH to RuIV=O efficiently. Surprisingly, this conversion can be further enhanced by the presence of perchlorate anions. Chronocoulometric data reveal that the alkyl chain on L promotes the adsorption of the ruthenium complex on the electrode surface. Bulk electrolysis results indicate that the [Ru(tpy)(dppa)(OH2)]2+ (dppa=(2,2′-dipyridyl)-n-propylamine) gives the most active electrocatalytic water oxidation activity among the ruthenium-aqua complexes investigated in this study.",

keywords = "coordination chemistry, electrocatalysis, pyridyl ligand, ruthenium(IV)-oxo complexes, water oxidation",

author = "Tsang, {Chui Shan} and Lee, {Lawrence Yoon Suk} and Cheung, {Kwong Chak} and Chan, {Pak Ho} and Wong, {Wing Leung} and Wong, {Kwok Yin}",

note = "Funding Information: This work was supported by the Innovation and Technology Commission and The Hong Kong Polytechnic University. KYW acknowledges the support from the Patrick S.C. Poon endowed professorship. Prof. Zhongyuan Zhou is acknowledged for the structural determination of the ruthenium complexes. Publisher Copyright: {\textcopyright} 2021 Wiley-VCH GmbH",

year = "2021",

month = jun,

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doi = "10.1002/celc.202100364",

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T1 - Unexpected Promotional Effects of Alkyl-Tailed Ligands and Anions on the Electrochemical Generation of Ruthenium(IV)-Oxo Complexes

AU - Tsang, Chui Shan

AU - Lee, Lawrence Yoon Suk

AU - Cheung, Kwong Chak

AU - Chan, Pak Ho

AU - Wong, Wing Leung

AU - Wong, Kwok Yin

N1 - Funding Information: This work was supported by the Innovation and Technology Commission and The Hong Kong Polytechnic University. KYW acknowledges the support from the Patrick S.C. Poon endowed professorship. Prof. Zhongyuan Zhou is acknowledged for the structural determination of the ruthenium complexes. Publisher Copyright: © 2021 Wiley-VCH GmbH

PY - 2021/6/14

Y1 - 2021/6/14

N2 - Electro-generation of RuIV=O species from the RuII-aqua complex is a crucial step to excel the electrocatalytic water oxidation performance of ruthenium oxo complexes. We report herein the synthesis and X-ray crystal structural characterizations of new RuII-aqua complexes containing N-substituted 2,2′-dipyridylamine ligands (L) tagged with an alkyl chain of various lengths, [Ru(tpy)(L)(OH2)]2+. Cyclic voltammetric analyses show that the length of the alkyl chain exerts great influence on the electro-generation of RuIV=O species. The L with a longer alkyl chain in an acidic aqueous medium promotes the conversion of RuIII−OH to RuIV=O efficiently. Surprisingly, this conversion can be further enhanced by the presence of perchlorate anions. Chronocoulometric data reveal that the alkyl chain on L promotes the adsorption of the ruthenium complex on the electrode surface. Bulk electrolysis results indicate that the [Ru(tpy)(dppa)(OH2)]2+ (dppa=(2,2′-dipyridyl)-n-propylamine) gives the most active electrocatalytic water oxidation activity among the ruthenium-aqua complexes investigated in this study.

AB - Electro-generation of RuIV=O species from the RuII-aqua complex is a crucial step to excel the electrocatalytic water oxidation performance of ruthenium oxo complexes. We report herein the synthesis and X-ray crystal structural characterizations of new RuII-aqua complexes containing N-substituted 2,2′-dipyridylamine ligands (L) tagged with an alkyl chain of various lengths, [Ru(tpy)(L)(OH2)]2+. Cyclic voltammetric analyses show that the length of the alkyl chain exerts great influence on the electro-generation of RuIV=O species. The L with a longer alkyl chain in an acidic aqueous medium promotes the conversion of RuIII−OH to RuIV=O efficiently. Surprisingly, this conversion can be further enhanced by the presence of perchlorate anions. Chronocoulometric data reveal that the alkyl chain on L promotes the adsorption of the ruthenium complex on the electrode surface. Bulk electrolysis results indicate that the [Ru(tpy)(dppa)(OH2)]2+ (dppa=(2,2′-dipyridyl)-n-propylamine) gives the most active electrocatalytic water oxidation activity among the ruthenium-aqua complexes investigated in this study.

KW - coordination chemistry

KW - electrocatalysis

KW - pyridyl ligand

KW - ruthenium(IV)-oxo complexes

KW - water oxidation

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DO - 10.1002/celc.202100364

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VL - 8

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EP - 2230

JO - ChemElectroChem

JF - ChemElectroChem

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ER -

Unexpected Promotional Effects of Alkyl-Tailed Ligands and Anions on the Electrochemical Generation of Ruthenium(IV)-Oxo Complexes

Abstract

Keywords

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