Cobalt(III) tetraaza-macrocyclic complexes as efficient catalyst for photoinduced hydrogen production in water: Theoretical investigation of the electronic structure of the reduced species and mechanistic insight

Robin Gueret; Carmen E. Castillo; Mateusz Rebarz; Fabrice Thomas; Aaron Albert Hargrove; Jacques Pécaut; Michel Sliwa; Jérôme Fortage; Marie Noëlle Collomb

doi:10.1016/j.jphotobiol.2015.04.010

Cobalt(III) tetraaza-macrocyclic complexes as efficient catalyst for photoinduced hydrogen production in water: Theoretical investigation of the electronic structure of the reduced species and mechanistic insight

Robin Gueret
, Carmen E. Castillo
, Mateusz Rebarz
, Fabrice Thomas
, Aaron Albert Hargrove
, Jacques Pécaut
, Michel Sliwa
, Jérôme Fortage
, Marie Noëlle Collomb

LTHE (UMR 5564 CNRS/IRD/Université de Grenoble)
Centre national de la recherche scientifique
Laboratoire de Spectrochimie Infrarouge et Raman, Université des Sciences et Technologies de Lille, UMR-CNRS 8516
Univ. Joseph Fourier-Grenoble 1

Research output: Contribution to journal › Article › peer-review

28 Citations (Scopus)

Abstract

We recently reported a very efficient homogeneous system for visible-light driven hydrogen production in water based on the cobalt(III) tetraaza-macrocyclic complex [Co(CR)Cl₂]⁺ (1) (CR = 2,12-dimethyl-3,7,11,17-tetra-azabicyclo(11.3.1)-heptadeca-1(17),2,11,13,15-pentaene) as a noble metal-free catalyst, with [Ru^II(bpy)₃]²⁺ (Ru) as photosensitizer and ascorbate/ascorbic acid (HA^-/H₂A) as a sacrificial electron donor and buffer (PhysChemChemPhys 2013, 15, 17544). This catalyst presents the particularity to achieve very high turnover numbers (TONs) (up to 1000) at pH 4.0 at a relative high concentration (0.1 mM) generating a large amount of hydrogen and having a long term stability. A similar activity was observed for the aquo derivative [Co^III(CR)(H₂O)₂]³⁺ (2) due to substitution of chloro ligands by water molecule in water. In this work, the geometry and electronic structures of 2 and its analog [Zn^II(CR)Cl]⁺ (3) derivative containing the redox innocent Zn(II) metal ion have been investigated by DFT calculations under various oxidation states. We also further studied the photocatalytic activity of this system and evaluated the influence of varying the relative concentration of the different components on the H₂-evolving activity. Turnover numbers versus catalyst (TON_Cat) were found to be dependent on the catalyst concentration with the highest value of 1130 obtained at 0.05 mM. Interestingly, the analogous nickel derivative, [Ni^II(CR)Cl₂] (4), when tested under the same experimental conditions was found to be fully inactive for H₂ production. Nanosecond transient absorption spectroscopy measurements have revealed that the first electron-transfer steps of the photocatalytic H₂-evolution mechanism with the Ru/cobalt tetraaza/HA^-/H₂A system involve a reductive quenching of the excited state of the photosensitizer by ascorbate (k_q = 2.5 × 10⁷ M^-¹ s^-¹) followed by an electron transfer from the reduced photosensitizer to the catalyst (k_et = 1.4 × 10⁹ M^-¹ s^-¹). The reduced catalyst can then enter into the cycle of hydrogen evolution.

Original language	English
Pages (from-to)	82-94
Number of pages	13
Journal	Journal of Photochemistry and Photobiology B: Biology
Volume	152
DOIs	https://doi.org/10.1016/j.jphotobiol.2015.04.010
Publication status	Published - 14 Jan 2015
Externally published	Yes

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

SDG 7 Affordable and Clean Energy

Keywords

Cobalt
Hydrogen
Macrocyclic ligand
Photocatalysis
Water chemistry

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Gueret, R., Castillo, C. E., Rebarz, M., Thomas, F., Hargrove, A. A., Pécaut, J., Sliwa, M., Fortage, J., & Collomb, M. N. (2015). Cobalt(III) tetraaza-macrocyclic complexes as efficient catalyst for photoinduced hydrogen production in water: Theoretical investigation of the electronic structure of the reduced species and mechanistic insight. Journal of Photochemistry and Photobiology B: Biology, 152, 82-94. https://doi.org/10.1016/j.jphotobiol.2015.04.010

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title = "Cobalt(III) tetraaza-macrocyclic complexes as efficient catalyst for photoinduced hydrogen production in water: Theoretical investigation of the electronic structure of the reduced species and mechanistic insight",

abstract = "We recently reported a very efficient homogeneous system for visible-light driven hydrogen production in water based on the cobalt(III) tetraaza-macrocyclic complex [Co(CR)Cl2]+ (1) (CR = 2,12-dimethyl-3,7,11,17-tetra-azabicyclo(11.3.1)-heptadeca-1(17),2,11,13,15-pentaene) as a noble metal-free catalyst, with [RuII(bpy)3]2+ (Ru) as photosensitizer and ascorbate/ascorbic acid (HA-/H2A) as a sacrificial electron donor and buffer (PhysChemChemPhys 2013, 15, 17544). This catalyst presents the particularity to achieve very high turnover numbers (TONs) (up to 1000) at pH 4.0 at a relative high concentration (0.1 mM) generating a large amount of hydrogen and having a long term stability. A similar activity was observed for the aquo derivative [CoIII(CR)(H2O)2]3+ (2) due to substitution of chloro ligands by water molecule in water. In this work, the geometry and electronic structures of 2 and its analog [ZnII(CR)Cl]+ (3) derivative containing the redox innocent Zn(II) metal ion have been investigated by DFT calculations under various oxidation states. We also further studied the photocatalytic activity of this system and evaluated the influence of varying the relative concentration of the different components on the H2-evolving activity. Turnover numbers versus catalyst (TONCat) were found to be dependent on the catalyst concentration with the highest value of 1130 obtained at 0.05 mM. Interestingly, the analogous nickel derivative, [NiII(CR)Cl2] (4), when tested under the same experimental conditions was found to be fully inactive for H2 production. Nanosecond transient absorption spectroscopy measurements have revealed that the first electron-transfer steps of the photocatalytic H2-evolution mechanism with the Ru/cobalt tetraaza/HA-/H2A system involve a reductive quenching of the excited state of the photosensitizer by ascorbate (kq = 2.5 {\texttimes} 107 M-1 s-1) followed by an electron transfer from the reduced photosensitizer to the catalyst (ket = 1.4 {\texttimes} 109 M-1 s-1). The reduced catalyst can then enter into the cycle of hydrogen evolution.",

keywords = "Cobalt, Hydrogen, Macrocyclic ligand, Photocatalysis, Water chemistry",

author = "Robin Gueret and Castillo, \{Carmen E.\} and Mateusz Rebarz and Fabrice Thomas and Hargrove, \{Aaron Albert\} and Jacques P{\'e}caut and Michel Sliwa and J{\'e}r{\^o}me Fortage and Collomb, \{Marie No{\"e}lle\}",

year = "2015",

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day = "14",

doi = "10.1016/j.jphotobiol.2015.04.010",

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Gueret, R, Castillo, CE, Rebarz, M, Thomas, F, Hargrove, AA, Pécaut, J, Sliwa, M, Fortage, J & Collomb, MN 2015, 'Cobalt(III) tetraaza-macrocyclic complexes as efficient catalyst for photoinduced hydrogen production in water: Theoretical investigation of the electronic structure of the reduced species and mechanistic insight', Journal of Photochemistry and Photobiology B: Biology, vol. 152, pp. 82-94. https://doi.org/10.1016/j.jphotobiol.2015.04.010

Cobalt(III) tetraaza-macrocyclic complexes as efficient catalyst for photoinduced hydrogen production in water: Theoretical investigation of the electronic structure of the reduced species and mechanistic insight. / Gueret, Robin; Castillo, Carmen E.; Rebarz, Mateusz et al.
In: Journal of Photochemistry and Photobiology B: Biology, Vol. 152, 14.01.2015, p. 82-94.

Research output: Contribution to journal › Article › peer-review

TY - JOUR

T1 - Cobalt(III) tetraaza-macrocyclic complexes as efficient catalyst for photoinduced hydrogen production in water

T2 - Theoretical investigation of the electronic structure of the reduced species and mechanistic insight

AU - Gueret, Robin

AU - Castillo, Carmen E.

AU - Rebarz, Mateusz

AU - Thomas, Fabrice

AU - Hargrove, Aaron Albert

AU - Pécaut, Jacques

AU - Sliwa, Michel

AU - Fortage, Jérôme

AU - Collomb, Marie Noëlle

PY - 2015/1/14

Y1 - 2015/1/14

N2 - We recently reported a very efficient homogeneous system for visible-light driven hydrogen production in water based on the cobalt(III) tetraaza-macrocyclic complex [Co(CR)Cl2]+ (1) (CR = 2,12-dimethyl-3,7,11,17-tetra-azabicyclo(11.3.1)-heptadeca-1(17),2,11,13,15-pentaene) as a noble metal-free catalyst, with [RuII(bpy)3]2+ (Ru) as photosensitizer and ascorbate/ascorbic acid (HA-/H2A) as a sacrificial electron donor and buffer (PhysChemChemPhys 2013, 15, 17544). This catalyst presents the particularity to achieve very high turnover numbers (TONs) (up to 1000) at pH 4.0 at a relative high concentration (0.1 mM) generating a large amount of hydrogen and having a long term stability. A similar activity was observed for the aquo derivative [CoIII(CR)(H2O)2]3+ (2) due to substitution of chloro ligands by water molecule in water. In this work, the geometry and electronic structures of 2 and its analog [ZnII(CR)Cl]+ (3) derivative containing the redox innocent Zn(II) metal ion have been investigated by DFT calculations under various oxidation states. We also further studied the photocatalytic activity of this system and evaluated the influence of varying the relative concentration of the different components on the H2-evolving activity. Turnover numbers versus catalyst (TONCat) were found to be dependent on the catalyst concentration with the highest value of 1130 obtained at 0.05 mM. Interestingly, the analogous nickel derivative, [NiII(CR)Cl2] (4), when tested under the same experimental conditions was found to be fully inactive for H2 production. Nanosecond transient absorption spectroscopy measurements have revealed that the first electron-transfer steps of the photocatalytic H2-evolution mechanism with the Ru/cobalt tetraaza/HA-/H2A system involve a reductive quenching of the excited state of the photosensitizer by ascorbate (kq = 2.5 × 107 M-1 s-1) followed by an electron transfer from the reduced photosensitizer to the catalyst (ket = 1.4 × 109 M-1 s-1). The reduced catalyst can then enter into the cycle of hydrogen evolution.

AB - We recently reported a very efficient homogeneous system for visible-light driven hydrogen production in water based on the cobalt(III) tetraaza-macrocyclic complex [Co(CR)Cl2]+ (1) (CR = 2,12-dimethyl-3,7,11,17-tetra-azabicyclo(11.3.1)-heptadeca-1(17),2,11,13,15-pentaene) as a noble metal-free catalyst, with [RuII(bpy)3]2+ (Ru) as photosensitizer and ascorbate/ascorbic acid (HA-/H2A) as a sacrificial electron donor and buffer (PhysChemChemPhys 2013, 15, 17544). This catalyst presents the particularity to achieve very high turnover numbers (TONs) (up to 1000) at pH 4.0 at a relative high concentration (0.1 mM) generating a large amount of hydrogen and having a long term stability. A similar activity was observed for the aquo derivative [CoIII(CR)(H2O)2]3+ (2) due to substitution of chloro ligands by water molecule in water. In this work, the geometry and electronic structures of 2 and its analog [ZnII(CR)Cl]+ (3) derivative containing the redox innocent Zn(II) metal ion have been investigated by DFT calculations under various oxidation states. We also further studied the photocatalytic activity of this system and evaluated the influence of varying the relative concentration of the different components on the H2-evolving activity. Turnover numbers versus catalyst (TONCat) were found to be dependent on the catalyst concentration with the highest value of 1130 obtained at 0.05 mM. Interestingly, the analogous nickel derivative, [NiII(CR)Cl2] (4), when tested under the same experimental conditions was found to be fully inactive for H2 production. Nanosecond transient absorption spectroscopy measurements have revealed that the first electron-transfer steps of the photocatalytic H2-evolution mechanism with the Ru/cobalt tetraaza/HA-/H2A system involve a reductive quenching of the excited state of the photosensitizer by ascorbate (kq = 2.5 × 107 M-1 s-1) followed by an electron transfer from the reduced photosensitizer to the catalyst (ket = 1.4 × 109 M-1 s-1). The reduced catalyst can then enter into the cycle of hydrogen evolution.

KW - Cobalt

KW - Hydrogen

KW - Macrocyclic ligand

KW - Photocatalysis

KW - Water chemistry

U2 - 10.1016/j.jphotobiol.2015.04.010

DO - 10.1016/j.jphotobiol.2015.04.010

M3 - Article

C2 - 25997378

AN - SCOPUS:84947044062

SN - 1011-1344

VL - 152

SP - 82

EP - 94

JO - Journal of Photochemistry and Photobiology B: Biology

JF - Journal of Photochemistry and Photobiology B: Biology

ER -

Gueret R, Castillo CE, Rebarz M, Thomas F, Hargrove AA, Pécaut J et al. Cobalt(III) tetraaza-macrocyclic complexes as efficient catalyst for photoinduced hydrogen production in water: Theoretical investigation of the electronic structure of the reduced species and mechanistic insight. Journal of Photochemistry and Photobiology B: Biology. 2015 Jan 14;152:82-94. doi: 10.1016/j.jphotobiol.2015.04.010