Photo-hydrogen-evolving molecular catalysts consisting of polypyridyl ruthenium(II) photosensitizers and platinum(II) catalysts: Insights into the reaction mechanism

Hironobu Ozawa, Masayuki Kobayashi, Bijitha Balan, Shigeyuki Masaoka, Ken Sakai

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

The mechanism of photoinduced hydrogen evolution from water driven by the first photo-hydrogenevolving molecular catalyst (1), given by a coupling of [Ru(bpy)2(5-aminophen)]2+ and [PtCl2(4,4'- dicarboxybpy)] (bpy=2,2'-bipyridine, phen=1,10-phenanthroline), was investigated in detail. The H2 evolution rate was found to obey Michaelis-Menten enzymatic kinetics with regard to the concentration of EDTA (ethylenediamine tetra-acetic acid disodium salt, sacrificial electron donor), which indicates that an ion-pair formation between the dicationic 1 and the dianionic form of EDTA (pH 5) is a key step leading to H2 formation. A 2:1 coupling product of 1 and ethylenediamine (i.e., a {RuII2Pt II2} complex 2) was found to show significantly higher photo-hydrogen-evolving (PHE) activity than 1, which revealed the validity of the bimolecular activation proposed in our previous study. The PHE activity of 2 was also observed to be linear to the concentration of 2, which indicates that H2 formation through the intermolecular path competes with the intramolecular path. Molecular orbital diagrams, conformational features, and Pt···H(water or acetic acid) hydrogen bonds were characterized by DFT calculations.

Original languageEnglish
Pages (from-to)1860-1869
Number of pages10
JournalChemistry - An Asian Journal
Volume5
Issue number8
DOIs
Publication statusPublished - Aug 2 2010

Fingerprint

ethylenediamine
Photosensitizing Agents
Ruthenium
Platinum
Hydrogen
Edetic Acid
Acetic Acid
Catalysts
2,2'-Dipyridyl
Water
Molecular orbitals
Discrete Fourier transforms
Hydrogen bonds
Salts
Chemical activation
Ions
Kinetics
Electrons

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Organic Chemistry

Cite this

Photo-hydrogen-evolving molecular catalysts consisting of polypyridyl ruthenium(II) photosensitizers and platinum(II) catalysts : Insights into the reaction mechanism. / Ozawa, Hironobu; Kobayashi, Masayuki; Balan, Bijitha; Masaoka, Shigeyuki; Sakai, Ken.

In: Chemistry - An Asian Journal, Vol. 5, No. 8, 02.08.2010, p. 1860-1869.

Research output: Contribution to journalArticle

@article{780697b1ea63498ab3a5f3d67c8574fc,
title = "Photo-hydrogen-evolving molecular catalysts consisting of polypyridyl ruthenium(II) photosensitizers and platinum(II) catalysts: Insights into the reaction mechanism",
abstract = "The mechanism of photoinduced hydrogen evolution from water driven by the first photo-hydrogenevolving molecular catalyst (1), given by a coupling of [Ru(bpy)2(5-aminophen)]2+ and [PtCl2(4,4'- dicarboxybpy)] (bpy=2,2'-bipyridine, phen=1,10-phenanthroline), was investigated in detail. The H2 evolution rate was found to obey Michaelis-Menten enzymatic kinetics with regard to the concentration of EDTA (ethylenediamine tetra-acetic acid disodium salt, sacrificial electron donor), which indicates that an ion-pair formation between the dicationic 1 and the dianionic form of EDTA (pH 5) is a key step leading to H2 formation. A 2:1 coupling product of 1 and ethylenediamine (i.e., a {RuII2Pt II2} complex 2) was found to show significantly higher photo-hydrogen-evolving (PHE) activity than 1, which revealed the validity of the bimolecular activation proposed in our previous study. The PHE activity of 2 was also observed to be linear to the concentration of 2, which indicates that H2 formation through the intermolecular path competes with the intramolecular path. Molecular orbital diagrams, conformational features, and Pt···H(water or acetic acid) hydrogen bonds were characterized by DFT calculations.",
author = "Hironobu Ozawa and Masayuki Kobayashi and Bijitha Balan and Shigeyuki Masaoka and Ken Sakai",
year = "2010",
month = "8",
day = "2",
doi = "10.1002/asia.201000083",
language = "English",
volume = "5",
pages = "1860--1869",
journal = "Chemistry - An Asian Journal",
issn = "1861-4728",
publisher = "John Wiley and Sons Ltd",
number = "8",

}

TY - JOUR

T1 - Photo-hydrogen-evolving molecular catalysts consisting of polypyridyl ruthenium(II) photosensitizers and platinum(II) catalysts

T2 - Insights into the reaction mechanism

AU - Ozawa, Hironobu

AU - Kobayashi, Masayuki

AU - Balan, Bijitha

AU - Masaoka, Shigeyuki

AU - Sakai, Ken

PY - 2010/8/2

Y1 - 2010/8/2

N2 - The mechanism of photoinduced hydrogen evolution from water driven by the first photo-hydrogenevolving molecular catalyst (1), given by a coupling of [Ru(bpy)2(5-aminophen)]2+ and [PtCl2(4,4'- dicarboxybpy)] (bpy=2,2'-bipyridine, phen=1,10-phenanthroline), was investigated in detail. The H2 evolution rate was found to obey Michaelis-Menten enzymatic kinetics with regard to the concentration of EDTA (ethylenediamine tetra-acetic acid disodium salt, sacrificial electron donor), which indicates that an ion-pair formation between the dicationic 1 and the dianionic form of EDTA (pH 5) is a key step leading to H2 formation. A 2:1 coupling product of 1 and ethylenediamine (i.e., a {RuII2Pt II2} complex 2) was found to show significantly higher photo-hydrogen-evolving (PHE) activity than 1, which revealed the validity of the bimolecular activation proposed in our previous study. The PHE activity of 2 was also observed to be linear to the concentration of 2, which indicates that H2 formation through the intermolecular path competes with the intramolecular path. Molecular orbital diagrams, conformational features, and Pt···H(water or acetic acid) hydrogen bonds were characterized by DFT calculations.

AB - The mechanism of photoinduced hydrogen evolution from water driven by the first photo-hydrogenevolving molecular catalyst (1), given by a coupling of [Ru(bpy)2(5-aminophen)]2+ and [PtCl2(4,4'- dicarboxybpy)] (bpy=2,2'-bipyridine, phen=1,10-phenanthroline), was investigated in detail. The H2 evolution rate was found to obey Michaelis-Menten enzymatic kinetics with regard to the concentration of EDTA (ethylenediamine tetra-acetic acid disodium salt, sacrificial electron donor), which indicates that an ion-pair formation between the dicationic 1 and the dianionic form of EDTA (pH 5) is a key step leading to H2 formation. A 2:1 coupling product of 1 and ethylenediamine (i.e., a {RuII2Pt II2} complex 2) was found to show significantly higher photo-hydrogen-evolving (PHE) activity than 1, which revealed the validity of the bimolecular activation proposed in our previous study. The PHE activity of 2 was also observed to be linear to the concentration of 2, which indicates that H2 formation through the intermolecular path competes with the intramolecular path. Molecular orbital diagrams, conformational features, and Pt···H(water or acetic acid) hydrogen bonds were characterized by DFT calculations.

UR - http://www.scopus.com/inward/record.url?scp=84962384851&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84962384851&partnerID=8YFLogxK

U2 - 10.1002/asia.201000083

DO - 10.1002/asia.201000083

M3 - Article

AN - SCOPUS:84962384851

VL - 5

SP - 1860

EP - 1869

JO - Chemistry - An Asian Journal

JF - Chemistry - An Asian Journal

SN - 1861-4728

IS - 8

ER -