Synthesis, characterization, and spectroscopic analysis of antiaromatic benzofused metalloporphyrins

Shun Sugawara, Yusuke Hirata, Satoshi Kojima, Yohsuke Yamamoto, Eigo Miyazaki, Kazuo Takimiya, Shiro Matsukawa, Daisuke Hashizume, John MacK, Nagao Kobayashi, Zhen Fu, Karl M. Kadish, Young Mo Sung, Kil Suk Kim, Dongho Kim

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Abstract

A two-electron oxidation of the Cu II (9) and Zn II (12) complexes of tetraphenyltetrabenzoporphyrin (TPTBP) results in the formation of stable antiaromatic [(TPTBP)Cu II(H 2O)] 2+·2 [SbF 6] - (10) and [(TPTBP)Zn II(H 2O) 2] 2+·2 [SbF 6] - (13) with 16π electrons on the inner ligand perimeter. X-ray structures of the parent TPTBP complexes, the dications, and singly oxidized species [(TPTBP)Cu II] ·+[SbF 6] - (11) reveal that the use of TPTBP rather than a porphyrin ligand reduces the degree of nonplanarity in the 16π-electron species relative to the parent 18π complex. Significant high-field shifts of the 1H NMR signals of the outer ring protons and large positive values in calculations of nucleus-independent chemical shifts on the central cavity of the porphyrin ring provide unambiguous evidence for the antiaromatic character of the 16π Zn II species. A combination of magnetic circular dichroism spectroscopic studies and TD-DFT calculations on both the Zn II and Cu II species demonstrates that the main electronic bands of the dicationic species can be readily assigned by using Michl's 4N perimeter model. Femtosecond transient absorption studies clearly demonstrated that the number of π electrons on the inner ligand perimeter and the configuration of the central metal ion play a critical role in the excited-state relaxation dynamics. Redox potentials for conversion between the 16π, 17π, and 18π systems were measured by cyclic voltammetry in dichloromethane and benzonitrile, and UV/Vis spectra of each oxidation/reduction product were monitored by thin-layer spectroelectrochemistry.

Original languageEnglish
Pages (from-to)3566-3581
Number of pages16
JournalChemistry - A European Journal
Volume18
Issue number12
DOIs
Publication statusPublished - 2012 Mar 19

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Metalloporphyrins
Spectroscopic analysis
Electrons
Ligands
Porphyrins
Spectroelectrochemistry
Methylene Chloride
Dichloromethane
Chemical shift
Dichroism
Excited states
Discrete Fourier transforms
Cyclic voltammetry
Metal ions
Protons
Nuclear magnetic resonance
X rays
Oxidation

All Science Journal Classification (ASJC) codes

  • Chemistry(all)

Cite this

Sugawara, Shun ; Hirata, Yusuke ; Kojima, Satoshi ; Yamamoto, Yohsuke ; Miyazaki, Eigo ; Takimiya, Kazuo ; Matsukawa, Shiro ; Hashizume, Daisuke ; MacK, John ; Kobayashi, Nagao ; Fu, Zhen ; Kadish, Karl M. ; Sung, Young Mo ; Kim, Kil Suk ; Kim, Dongho. / Synthesis, characterization, and spectroscopic analysis of antiaromatic benzofused metalloporphyrins. In: Chemistry - A European Journal. 2012 ; Vol. 18, No. 12. pp. 3566-3581.
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title = "Synthesis, characterization, and spectroscopic analysis of antiaromatic benzofused metalloporphyrins",
abstract = "A two-electron oxidation of the Cu II (9) and Zn II (12) complexes of tetraphenyltetrabenzoporphyrin (TPTBP) results in the formation of stable antiaromatic [(TPTBP)Cu II(H 2O)] 2+·2 [SbF 6] - (10) and [(TPTBP)Zn II(H 2O) 2] 2+·2 [SbF 6] - (13) with 16π electrons on the inner ligand perimeter. X-ray structures of the parent TPTBP complexes, the dications, and singly oxidized species [(TPTBP)Cu II] ·+[SbF 6] - (11) reveal that the use of TPTBP rather than a porphyrin ligand reduces the degree of nonplanarity in the 16π-electron species relative to the parent 18π complex. Significant high-field shifts of the 1H NMR signals of the outer ring protons and large positive values in calculations of nucleus-independent chemical shifts on the central cavity of the porphyrin ring provide unambiguous evidence for the antiaromatic character of the 16π Zn II species. A combination of magnetic circular dichroism spectroscopic studies and TD-DFT calculations on both the Zn II and Cu II species demonstrates that the main electronic bands of the dicationic species can be readily assigned by using Michl's 4N perimeter model. Femtosecond transient absorption studies clearly demonstrated that the number of π electrons on the inner ligand perimeter and the configuration of the central metal ion play a critical role in the excited-state relaxation dynamics. Redox potentials for conversion between the 16π, 17π, and 18π systems were measured by cyclic voltammetry in dichloromethane and benzonitrile, and UV/Vis spectra of each oxidation/reduction product were monitored by thin-layer spectroelectrochemistry.",
author = "Shun Sugawara and Yusuke Hirata and Satoshi Kojima and Yohsuke Yamamoto and Eigo Miyazaki and Kazuo Takimiya and Shiro Matsukawa and Daisuke Hashizume and John MacK and Nagao Kobayashi and Zhen Fu and Kadish, {Karl M.} and Sung, {Young Mo} and Kim, {Kil Suk} and Dongho Kim",
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Sugawara, S, Hirata, Y, Kojima, S, Yamamoto, Y, Miyazaki, E, Takimiya, K, Matsukawa, S, Hashizume, D, MacK, J, Kobayashi, N, Fu, Z, Kadish, KM, Sung, YM, Kim, KS & Kim, D 2012, 'Synthesis, characterization, and spectroscopic analysis of antiaromatic benzofused metalloporphyrins', Chemistry - A European Journal, vol. 18, no. 12, pp. 3566-3581. https://doi.org/10.1002/chem.201101846

Synthesis, characterization, and spectroscopic analysis of antiaromatic benzofused metalloporphyrins. / Sugawara, Shun; Hirata, Yusuke; Kojima, Satoshi; Yamamoto, Yohsuke; Miyazaki, Eigo; Takimiya, Kazuo; Matsukawa, Shiro; Hashizume, Daisuke; MacK, John; Kobayashi, Nagao; Fu, Zhen; Kadish, Karl M.; Sung, Young Mo; Kim, Kil Suk; Kim, Dongho.

In: Chemistry - A European Journal, Vol. 18, No. 12, 19.03.2012, p. 3566-3581.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Synthesis, characterization, and spectroscopic analysis of antiaromatic benzofused metalloporphyrins

AU - Sugawara, Shun

AU - Hirata, Yusuke

AU - Kojima, Satoshi

AU - Yamamoto, Yohsuke

AU - Miyazaki, Eigo

AU - Takimiya, Kazuo

AU - Matsukawa, Shiro

AU - Hashizume, Daisuke

AU - MacK, John

AU - Kobayashi, Nagao

AU - Fu, Zhen

AU - Kadish, Karl M.

AU - Sung, Young Mo

AU - Kim, Kil Suk

AU - Kim, Dongho

PY - 2012/3/19

Y1 - 2012/3/19

N2 - A two-electron oxidation of the Cu II (9) and Zn II (12) complexes of tetraphenyltetrabenzoporphyrin (TPTBP) results in the formation of stable antiaromatic [(TPTBP)Cu II(H 2O)] 2+·2 [SbF 6] - (10) and [(TPTBP)Zn II(H 2O) 2] 2+·2 [SbF 6] - (13) with 16π electrons on the inner ligand perimeter. X-ray structures of the parent TPTBP complexes, the dications, and singly oxidized species [(TPTBP)Cu II] ·+[SbF 6] - (11) reveal that the use of TPTBP rather than a porphyrin ligand reduces the degree of nonplanarity in the 16π-electron species relative to the parent 18π complex. Significant high-field shifts of the 1H NMR signals of the outer ring protons and large positive values in calculations of nucleus-independent chemical shifts on the central cavity of the porphyrin ring provide unambiguous evidence for the antiaromatic character of the 16π Zn II species. A combination of magnetic circular dichroism spectroscopic studies and TD-DFT calculations on both the Zn II and Cu II species demonstrates that the main electronic bands of the dicationic species can be readily assigned by using Michl's 4N perimeter model. Femtosecond transient absorption studies clearly demonstrated that the number of π electrons on the inner ligand perimeter and the configuration of the central metal ion play a critical role in the excited-state relaxation dynamics. Redox potentials for conversion between the 16π, 17π, and 18π systems were measured by cyclic voltammetry in dichloromethane and benzonitrile, and UV/Vis spectra of each oxidation/reduction product were monitored by thin-layer spectroelectrochemistry.

AB - A two-electron oxidation of the Cu II (9) and Zn II (12) complexes of tetraphenyltetrabenzoporphyrin (TPTBP) results in the formation of stable antiaromatic [(TPTBP)Cu II(H 2O)] 2+·2 [SbF 6] - (10) and [(TPTBP)Zn II(H 2O) 2] 2+·2 [SbF 6] - (13) with 16π electrons on the inner ligand perimeter. X-ray structures of the parent TPTBP complexes, the dications, and singly oxidized species [(TPTBP)Cu II] ·+[SbF 6] - (11) reveal that the use of TPTBP rather than a porphyrin ligand reduces the degree of nonplanarity in the 16π-electron species relative to the parent 18π complex. Significant high-field shifts of the 1H NMR signals of the outer ring protons and large positive values in calculations of nucleus-independent chemical shifts on the central cavity of the porphyrin ring provide unambiguous evidence for the antiaromatic character of the 16π Zn II species. A combination of magnetic circular dichroism spectroscopic studies and TD-DFT calculations on both the Zn II and Cu II species demonstrates that the main electronic bands of the dicationic species can be readily assigned by using Michl's 4N perimeter model. Femtosecond transient absorption studies clearly demonstrated that the number of π electrons on the inner ligand perimeter and the configuration of the central metal ion play a critical role in the excited-state relaxation dynamics. Redox potentials for conversion between the 16π, 17π, and 18π systems were measured by cyclic voltammetry in dichloromethane and benzonitrile, and UV/Vis spectra of each oxidation/reduction product were monitored by thin-layer spectroelectrochemistry.

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U2 - 10.1002/chem.201101846

DO - 10.1002/chem.201101846

M3 - Article

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EP - 3581

JO - Chemistry - A European Journal

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SN - 0947-6539

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