Climbing over the activity volcano correlation by biomimicking Vitamin B12

A co phthalocyanine pyridine axial ligand coordinated catalyst for the reduction of molecular oxygen

Jorge Riquelme, Karinna Neira, José F. Marco, Patricio Hcrmosilla, Diego Vencgas, Walter Orellana, Ingrid Ponce, José H. Zagal, Federico Tasca

Resultado de la investigación: Conference contribution

Resumen

CoN4 macrocyclic complexes like Co phthalocyanines (CoPc) have been extensively studied as electrocatalysts for the ORR but they preferentially promote the 2-e reduction of O2 to give peroxide. In contrast, Vitamin B12, a naturally occurring CoN4 macrocyclic molecule alkaline media promotes the 4-electron reduction of O2 to H2O. Vitamin B12 possesses an imidazole axial back ligand and this seems to be the reason for its higher activity and selectivity for the 4-e reduction of O2. To test this hypothesis, we synthesized a CoPc axially coordinated to pyridine anchored to carbon nanotubes (Co-Py-CNT). The Co center is therefore coordinated to 5 nitrogens as in Vitamin B12. The modified CoPcPy containing catalytic material was characterized by EPR and XPS spectroscopy. DFT calculations. According to our results the pyridine back ligand increases the Co-O2 binding energy, making it more similar to VitB12, favoring the splitting of the O-O bond. The back ligand then plays a crucial role in modifying Co-O2 binding energy which is a well know reactivity descriptor. A further evidence of this dramatic change in reactivity of CoPc by the presence of the "Py" back ligand is that it moves from the weak binding leg of a volcano correlation to the strong leg of the volcano. This might explain why nature uses a back ligand in cytochrome c to catalyze the ORR.

Idioma originalEnglish
Título de la publicación alojadaECS Transactions
EditorialElectrochemical Society, Inc.
Páginas111-121
Número de páginas11
Volumen85
Edición12
ISBN (versión digital)9781607685395
DOI
EstadoPublished - 1 ene 2018
EventoElectrocatalysis 9: Symposium in Honor of Radoslav Adzic - 233rd ECS Meeting - Seattle, United States
Duración: 13 may 201817 may 2018

Conference

ConferenceElectrocatalysis 9: Symposium in Honor of Radoslav Adzic - 233rd ECS Meeting
PaísUnited States
CiudadSeattle
Período13/05/1817/05/18

Huella dactilar

Volcanoes
Molecular oxygen
Vitamins
Pyridine
Ligands
Catalysts
Binding energy
Electrocatalysts
Peroxides
Discrete Fourier transforms
Paramagnetic resonance
Carbon nanotubes
X ray photoelectron spectroscopy
Spectroscopy
Nitrogen
Proteins
Molecules
Electrons

ASJC Scopus subject areas

  • Engineering(all)

Citar esto

Riquelme, J., Neira, K., Marco, J. F., Hcrmosilla, P., Vencgas, D., Orellana, W., ... Tasca, F. (2018). Climbing over the activity volcano correlation by biomimicking Vitamin B12: A co phthalocyanine pyridine axial ligand coordinated catalyst for the reduction of molecular oxygen. En ECS Transactions (12 ed., Vol. 85, pp. 111-121). Electrochemical Society, Inc.. https://doi.org/10.1149/08512.01ecst
Riquelme, Jorge ; Neira, Karinna ; Marco, José F. ; Hcrmosilla, Patricio ; Vencgas, Diego ; Orellana, Walter ; Ponce, Ingrid ; Zagal, José H. ; Tasca, Federico. / Climbing over the activity volcano correlation by biomimicking Vitamin B12 : A co phthalocyanine pyridine axial ligand coordinated catalyst for the reduction of molecular oxygen. ECS Transactions. Vol. 85 12. ed. Electrochemical Society, Inc., 2018. pp. 111-121
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abstract = "CoN4 macrocyclic complexes like Co phthalocyanines (CoPc) have been extensively studied as electrocatalysts for the ORR but they preferentially promote the 2-e reduction of O2 to give peroxide. In contrast, Vitamin B12, a naturally occurring CoN4 macrocyclic molecule alkaline media promotes the 4-electron reduction of O2 to H2O. Vitamin B12 possesses an imidazole axial back ligand and this seems to be the reason for its higher activity and selectivity for the 4-e reduction of O2. To test this hypothesis, we synthesized a CoPc axially coordinated to pyridine anchored to carbon nanotubes (Co-Py-CNT). The Co center is therefore coordinated to 5 nitrogens as in Vitamin B12. The modified CoPcPy containing catalytic material was characterized by EPR and XPS spectroscopy. DFT calculations. According to our results the pyridine back ligand increases the Co-O2 binding energy, making it more similar to VitB12, favoring the splitting of the O-O bond. The back ligand then plays a crucial role in modifying Co-O2 binding energy which is a well know reactivity descriptor. A further evidence of this dramatic change in reactivity of CoPc by the presence of the {"}Py{"} back ligand is that it moves from the weak binding leg of a volcano correlation to the strong leg of the volcano. This might explain why nature uses a back ligand in cytochrome c to catalyze the ORR.",
author = "Jorge Riquelme and Karinna Neira and Marco, {Jos{\'e} F.} and Patricio Hcrmosilla and Diego Vencgas and Walter Orellana and Ingrid Ponce and Zagal, {Jos{\'e} H.} and Federico Tasca",
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Riquelme, J, Neira, K, Marco, JF, Hcrmosilla, P, Vencgas, D, Orellana, W, Ponce, I, Zagal, JH & Tasca, F 2018, Climbing over the activity volcano correlation by biomimicking Vitamin B12: A co phthalocyanine pyridine axial ligand coordinated catalyst for the reduction of molecular oxygen. En ECS Transactions. 12 ed., vol. 85, Electrochemical Society, Inc., pp. 111-121, Electrocatalysis 9: Symposium in Honor of Radoslav Adzic - 233rd ECS Meeting, Seattle, United States, 13/05/18. https://doi.org/10.1149/08512.01ecst

Climbing over the activity volcano correlation by biomimicking Vitamin B12 : A co phthalocyanine pyridine axial ligand coordinated catalyst for the reduction of molecular oxygen. / Riquelme, Jorge; Neira, Karinna; Marco, José F.; Hcrmosilla, Patricio; Vencgas, Diego; Orellana, Walter; Ponce, Ingrid; Zagal, José H.; Tasca, Federico.

ECS Transactions. Vol. 85 12. ed. Electrochemical Society, Inc., 2018. p. 111-121.

Resultado de la investigación: Conference contribution

TY - GEN

T1 - Climbing over the activity volcano correlation by biomimicking Vitamin B12

T2 - A co phthalocyanine pyridine axial ligand coordinated catalyst for the reduction of molecular oxygen

AU - Riquelme, Jorge

AU - Neira, Karinna

AU - Marco, José F.

AU - Hcrmosilla, Patricio

AU - Vencgas, Diego

AU - Orellana, Walter

AU - Ponce, Ingrid

AU - Zagal, José H.

AU - Tasca, Federico

PY - 2018/1/1

Y1 - 2018/1/1

N2 - CoN4 macrocyclic complexes like Co phthalocyanines (CoPc) have been extensively studied as electrocatalysts for the ORR but they preferentially promote the 2-e reduction of O2 to give peroxide. In contrast, Vitamin B12, a naturally occurring CoN4 macrocyclic molecule alkaline media promotes the 4-electron reduction of O2 to H2O. Vitamin B12 possesses an imidazole axial back ligand and this seems to be the reason for its higher activity and selectivity for the 4-e reduction of O2. To test this hypothesis, we synthesized a CoPc axially coordinated to pyridine anchored to carbon nanotubes (Co-Py-CNT). The Co center is therefore coordinated to 5 nitrogens as in Vitamin B12. The modified CoPcPy containing catalytic material was characterized by EPR and XPS spectroscopy. DFT calculations. According to our results the pyridine back ligand increases the Co-O2 binding energy, making it more similar to VitB12, favoring the splitting of the O-O bond. The back ligand then plays a crucial role in modifying Co-O2 binding energy which is a well know reactivity descriptor. A further evidence of this dramatic change in reactivity of CoPc by the presence of the "Py" back ligand is that it moves from the weak binding leg of a volcano correlation to the strong leg of the volcano. This might explain why nature uses a back ligand in cytochrome c to catalyze the ORR.

AB - CoN4 macrocyclic complexes like Co phthalocyanines (CoPc) have been extensively studied as electrocatalysts for the ORR but they preferentially promote the 2-e reduction of O2 to give peroxide. In contrast, Vitamin B12, a naturally occurring CoN4 macrocyclic molecule alkaline media promotes the 4-electron reduction of O2 to H2O. Vitamin B12 possesses an imidazole axial back ligand and this seems to be the reason for its higher activity and selectivity for the 4-e reduction of O2. To test this hypothesis, we synthesized a CoPc axially coordinated to pyridine anchored to carbon nanotubes (Co-Py-CNT). The Co center is therefore coordinated to 5 nitrogens as in Vitamin B12. The modified CoPcPy containing catalytic material was characterized by EPR and XPS spectroscopy. DFT calculations. According to our results the pyridine back ligand increases the Co-O2 binding energy, making it more similar to VitB12, favoring the splitting of the O-O bond. The back ligand then plays a crucial role in modifying Co-O2 binding energy which is a well know reactivity descriptor. A further evidence of this dramatic change in reactivity of CoPc by the presence of the "Py" back ligand is that it moves from the weak binding leg of a volcano correlation to the strong leg of the volcano. This might explain why nature uses a back ligand in cytochrome c to catalyze the ORR.

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U2 - 10.1149/08512.01ecst

DO - 10.1149/08512.01ecst

M3 - Conference contribution

VL - 85

SP - 111

EP - 121

BT - ECS Transactions

PB - Electrochemical Society, Inc.

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Riquelme J, Neira K, Marco JF, Hcrmosilla P, Vencgas D, Orellana W y otros. Climbing over the activity volcano correlation by biomimicking Vitamin B12: A co phthalocyanine pyridine axial ligand coordinated catalyst for the reduction of molecular oxygen. En ECS Transactions. 12 ed. Vol. 85. Electrochemical Society, Inc. 2018. p. 111-121 https://doi.org/10.1149/08512.01ecst