Reduction of cobalt and iron phthalocyanines and the role of the reduced species in catalyzed photoreduction of CO2

J. Grodkowski, T. Dhanasekaran, P. Neta, P. Hambright, B. S. Brunschwig, K. Shinozaki, Etsuko Fujita

Research output: Contribution to journalArticle

103 Citations (Scopus)

Abstract

The role of cobalt and iron phthalocyanines in catalytic CO2 reduction has been studied. Chemical, photochemical, and radiolytic reductions of the metal phthalocyanines (Pc) have been carried out in organic solvents, and reduction of their tetrasulfonated derivatives (TSPc) in aqueous solutions. CoIIPc and FeIIPc are readily reduced to [CoIPc]- and [FeIPc]-, which do not react with CO2. Reduction of [CoIPc]- yields a product which is characterized as the radical anion, [CoIPc·-]2-, on the basis of its absorption spectra in the visible and IR regions. This species is stable under dry anaerobic conditions and reacts rapidly with CO2. Catalytic formation of CO and formate is confirmed by photochemical experiments in DMF and acetonitrile solutions containing triehylamine (TEA) as a reductive quencher. The photochemical yields are greatly enhanced by the addition of p-terphenyl (TP). The radical anion. TP·-, formed from the reductive quenching of the singlet excited state with TEA, reduces the phthalocyanines very rapidly. The rate constants for reduction of CoIIPc, [CoIPc]-, and [FeIPc]- by TP·-, determined by pulse radiolysis in DMF solutions, are nearly diffusion-controlled. The mono-reduced species formed from [CoIPc]- is unstable under the pulse radiolysis conditions but is longer-lived under the flash photolysis conditions. The interaction of this species with CO2 is either too weak or too slow to detect in the current experiments, where a competing reaction with protons predominates.

Original languageEnglish
Pages (from-to)11332-11339
Number of pages8
JournalJournal of Physical Chemistry A
Volume104
Issue number48
DOIs
Publication statusPublished - Dec 7 2000

Fingerprint

photochemical reactions
cobalt
terphenyls
iron
Radiolysis
formic acid
radiolysis
Anions
anions
Photolysis
formates
Carbon Monoxide
pulses
Excited states
Organic solvents
acetonitrile
flash
photolysis
Protons
Absorption spectra

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Reduction of cobalt and iron phthalocyanines and the role of the reduced species in catalyzed photoreduction of CO2 . / Grodkowski, J.; Dhanasekaran, T.; Neta, P.; Hambright, P.; Brunschwig, B. S.; Shinozaki, K.; Fujita, Etsuko.

In: Journal of Physical Chemistry A, Vol. 104, No. 48, 07.12.2000, p. 11332-11339.

Research output: Contribution to journalArticle

Grodkowski, J, Dhanasekaran, T, Neta, P, Hambright, P, Brunschwig, BS, Shinozaki, K & Fujita, E 2000, 'Reduction of cobalt and iron phthalocyanines and the role of the reduced species in catalyzed photoreduction of CO2 ', Journal of Physical Chemistry A, vol. 104, no. 48, pp. 11332-11339. https://doi.org/10.1021/jp002709y
Grodkowski J, Dhanasekaran T, Neta P, Hambright P, Brunschwig BS, Shinozaki K et al. Reduction of cobalt and iron phthalocyanines and the role of the reduced species in catalyzed photoreduction of CO2 . Journal of Physical Chemistry A. 2000 Dec 7;104(48):11332-11339. https://doi.org/10.1021/jp002709y
Grodkowski, J. ; Dhanasekaran, T. ; Neta, P. ; Hambright, P. ; Brunschwig, B. S. ; Shinozaki, K. ; Fujita, Etsuko. / Reduction of cobalt and iron phthalocyanines and the role of the reduced species in catalyzed photoreduction of CO2 . In: Journal of Physical Chemistry A. 2000 ; Vol. 104, No. 48. pp. 11332-11339.
@article{994a942660784a5eb36eb6bb53be4fed,
title = "Reduction of cobalt and iron phthalocyanines and the role of the reduced species in catalyzed photoreduction of CO2",
abstract = "The role of cobalt and iron phthalocyanines in catalytic CO2 reduction has been studied. Chemical, photochemical, and radiolytic reductions of the metal phthalocyanines (Pc) have been carried out in organic solvents, and reduction of their tetrasulfonated derivatives (TSPc) in aqueous solutions. CoIIPc and FeIIPc are readily reduced to [CoIPc]- and [FeIPc]-, which do not react with CO2. Reduction of [CoIPc]- yields a product which is characterized as the radical anion, [CoIPc·-]2-, on the basis of its absorption spectra in the visible and IR regions. This species is stable under dry anaerobic conditions and reacts rapidly with CO2. Catalytic formation of CO and formate is confirmed by photochemical experiments in DMF and acetonitrile solutions containing triehylamine (TEA) as a reductive quencher. The photochemical yields are greatly enhanced by the addition of p-terphenyl (TP). The radical anion. TP·-, formed from the reductive quenching of the singlet excited state with TEA, reduces the phthalocyanines very rapidly. The rate constants for reduction of CoIIPc, [CoIPc]-, and [FeIPc]- by TP·-, determined by pulse radiolysis in DMF solutions, are nearly diffusion-controlled. The mono-reduced species formed from [CoIPc]- is unstable under the pulse radiolysis conditions but is longer-lived under the flash photolysis conditions. The interaction of this species with CO2 is either too weak or too slow to detect in the current experiments, where a competing reaction with protons predominates.",
author = "J. Grodkowski and T. Dhanasekaran and P. Neta and P. Hambright and Brunschwig, {B. S.} and K. Shinozaki and Etsuko Fujita",
year = "2000",
month = "12",
day = "7",
doi = "10.1021/jp002709y",
language = "English",
volume = "104",
pages = "11332--11339",
journal = "Journal of Physical Chemistry A",
issn = "1089-5639",
publisher = "American Chemical Society",
number = "48",

}

TY - JOUR

T1 - Reduction of cobalt and iron phthalocyanines and the role of the reduced species in catalyzed photoreduction of CO2

AU - Grodkowski, J.

AU - Dhanasekaran, T.

AU - Neta, P.

AU - Hambright, P.

AU - Brunschwig, B. S.

AU - Shinozaki, K.

AU - Fujita, Etsuko

PY - 2000/12/7

Y1 - 2000/12/7

N2 - The role of cobalt and iron phthalocyanines in catalytic CO2 reduction has been studied. Chemical, photochemical, and radiolytic reductions of the metal phthalocyanines (Pc) have been carried out in organic solvents, and reduction of their tetrasulfonated derivatives (TSPc) in aqueous solutions. CoIIPc and FeIIPc are readily reduced to [CoIPc]- and [FeIPc]-, which do not react with CO2. Reduction of [CoIPc]- yields a product which is characterized as the radical anion, [CoIPc·-]2-, on the basis of its absorption spectra in the visible and IR regions. This species is stable under dry anaerobic conditions and reacts rapidly with CO2. Catalytic formation of CO and formate is confirmed by photochemical experiments in DMF and acetonitrile solutions containing triehylamine (TEA) as a reductive quencher. The photochemical yields are greatly enhanced by the addition of p-terphenyl (TP). The radical anion. TP·-, formed from the reductive quenching of the singlet excited state with TEA, reduces the phthalocyanines very rapidly. The rate constants for reduction of CoIIPc, [CoIPc]-, and [FeIPc]- by TP·-, determined by pulse radiolysis in DMF solutions, are nearly diffusion-controlled. The mono-reduced species formed from [CoIPc]- is unstable under the pulse radiolysis conditions but is longer-lived under the flash photolysis conditions. The interaction of this species with CO2 is either too weak or too slow to detect in the current experiments, where a competing reaction with protons predominates.

AB - The role of cobalt and iron phthalocyanines in catalytic CO2 reduction has been studied. Chemical, photochemical, and radiolytic reductions of the metal phthalocyanines (Pc) have been carried out in organic solvents, and reduction of their tetrasulfonated derivatives (TSPc) in aqueous solutions. CoIIPc and FeIIPc are readily reduced to [CoIPc]- and [FeIPc]-, which do not react with CO2. Reduction of [CoIPc]- yields a product which is characterized as the radical anion, [CoIPc·-]2-, on the basis of its absorption spectra in the visible and IR regions. This species is stable under dry anaerobic conditions and reacts rapidly with CO2. Catalytic formation of CO and formate is confirmed by photochemical experiments in DMF and acetonitrile solutions containing triehylamine (TEA) as a reductive quencher. The photochemical yields are greatly enhanced by the addition of p-terphenyl (TP). The radical anion. TP·-, formed from the reductive quenching of the singlet excited state with TEA, reduces the phthalocyanines very rapidly. The rate constants for reduction of CoIIPc, [CoIPc]-, and [FeIPc]- by TP·-, determined by pulse radiolysis in DMF solutions, are nearly diffusion-controlled. The mono-reduced species formed from [CoIPc]- is unstable under the pulse radiolysis conditions but is longer-lived under the flash photolysis conditions. The interaction of this species with CO2 is either too weak or too slow to detect in the current experiments, where a competing reaction with protons predominates.

UR - http://www.scopus.com/inward/record.url?scp=0034514186&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0034514186&partnerID=8YFLogxK

U2 - 10.1021/jp002709y

DO - 10.1021/jp002709y

M3 - Article

AN - SCOPUS:0034514186

VL - 104

SP - 11332

EP - 11339

JO - Journal of Physical Chemistry A

JF - Journal of Physical Chemistry A

SN - 1089-5639

IS - 48

ER -