Exceptional electronic modulation of porphyrins through meso-arylethynyl groups. Electronic spectroscopy, electronic structure, and electrochemistry of [5,15-bis](aryl)ethynyl]-10,20-diphenylporphinato]zinc(II) complexes

Steven M. LeCours, Stephen DiMagno, Michael J. Therien

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Abstract

A new class of porphyrins in which intervening ethynyl moieties connect aryl groups to the porphyrin 5 and 15-positions is described. The synthesis and optical spectroscopy of five new compounds are reported: [5,15-bis[(4'-dimethylaminophenyl)ethynyl]-10,20-diphenylporphinato]zi nc(II), [5,15-bis[(4'-methoxyphenyl)ethynyl]-10,20-diphenylporphinato]zinc(II) , [5,15-bis[(phenyl)ethynyl]-10,20-diphenylporphinato]zinc(II), [5, 15-bis[(4'-fluorophenyl)ethynyl]-10,20-diphenylporphinato]zinc(II), and [5,15-bis[(4'-nitrophenyl)ethynyl]-10,20-diphenylporphinato]zinc(II). The X-ray structure of one of these complexes, [5,15-bis[(4'-fluorophenyl)ethynyl]-10,20-diphenylporphinato]zinc(II), is unusual in that it shows the arylethynyl-phenyl rings to be coplanar with the porphyrin macrocycle. This arrangement of aryl rings with respect to the porphyrin macrocycle underscores the fact that the steric barrier to rotation between the porphyrin and arylethynyl-phenyl aromatic systems has been removed and highlights the enhanced π-conjugative interactions responsible for the unusual electronic characteristics of these molecules. Electronic spectroscopy and electrochemistry of these systems evince the ability of this new porphyrin structural motif to modulate extensively chromophore electronic structure. ZINDO-determined (INDO-1 semiempirical parameters; CI level = 20) frontier orbital energies for the [5,15-bis[(aryl)ethynyl]-10,20-diphenylporphinato]zinc(II) complexes demonstrate that these properties derive from energetic differences between the porphyrin HOMO and HOMO-1 and a substantial splitting of the formerly degenerate porphyrin LUMO; these significant electronic perturbations (relative to simple (porphinato)zinc(II) complexes) are manifest in the fact that the low lying singlet excited states of these compounds are highly polarized.

Original languageEnglish (US)
Pages (from-to)11854-11864
Number of pages11
JournalJournal of the American Chemical Society
Volume118
Issue number47
DOIs
StatePublished - Nov 27 1996

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Electrochemistry
Porphyrins
Electronic structure
Zinc
Spectrum Analysis
Modulation
Spectroscopy
Chromophores
Excited states
X-Rays
X rays
Molecules

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

@article{e42d0769c4bf49718b4b48154a94f9a0,
title = "Exceptional electronic modulation of porphyrins through meso-arylethynyl groups. Electronic spectroscopy, electronic structure, and electrochemistry of [5,15-bis](aryl)ethynyl]-10,20-diphenylporphinato]zinc(II) complexes",
abstract = "A new class of porphyrins in which intervening ethynyl moieties connect aryl groups to the porphyrin 5 and 15-positions is described. The synthesis and optical spectroscopy of five new compounds are reported: [5,15-bis[(4'-dimethylaminophenyl)ethynyl]-10,20-diphenylporphinato]zi nc(II), [5,15-bis[(4'-methoxyphenyl)ethynyl]-10,20-diphenylporphinato]zinc(II) , [5,15-bis[(phenyl)ethynyl]-10,20-diphenylporphinato]zinc(II), [5, 15-bis[(4'-fluorophenyl)ethynyl]-10,20-diphenylporphinato]zinc(II), and [5,15-bis[(4'-nitrophenyl)ethynyl]-10,20-diphenylporphinato]zinc(II). The X-ray structure of one of these complexes, [5,15-bis[(4'-fluorophenyl)ethynyl]-10,20-diphenylporphinato]zinc(II), is unusual in that it shows the arylethynyl-phenyl rings to be coplanar with the porphyrin macrocycle. This arrangement of aryl rings with respect to the porphyrin macrocycle underscores the fact that the steric barrier to rotation between the porphyrin and arylethynyl-phenyl aromatic systems has been removed and highlights the enhanced π-conjugative interactions responsible for the unusual electronic characteristics of these molecules. Electronic spectroscopy and electrochemistry of these systems evince the ability of this new porphyrin structural motif to modulate extensively chromophore electronic structure. ZINDO-determined (INDO-1 semiempirical parameters; CI level = 20) frontier orbital energies for the [5,15-bis[(aryl)ethynyl]-10,20-diphenylporphinato]zinc(II) complexes demonstrate that these properties derive from energetic differences between the porphyrin HOMO and HOMO-1 and a substantial splitting of the formerly degenerate porphyrin LUMO; these significant electronic perturbations (relative to simple (porphinato)zinc(II) complexes) are manifest in the fact that the low lying singlet excited states of these compounds are highly polarized.",
author = "LeCours, {Steven M.} and Stephen DiMagno and Therien, {Michael J.}",
year = "1996",
month = "11",
day = "27",
doi = "10.1021/ja962403y",
language = "English (US)",
volume = "118",
pages = "11854--11864",
journal = "Journal of the American Chemical Society",
issn = "0002-7863",
publisher = "American Chemical Society",
number = "47",

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TY - JOUR

T1 - Exceptional electronic modulation of porphyrins through meso-arylethynyl groups. Electronic spectroscopy, electronic structure, and electrochemistry of [5,15-bis](aryl)ethynyl]-10,20-diphenylporphinato]zinc(II) complexes

AU - LeCours, Steven M.

AU - DiMagno, Stephen

AU - Therien, Michael J.

PY - 1996/11/27

Y1 - 1996/11/27

N2 - A new class of porphyrins in which intervening ethynyl moieties connect aryl groups to the porphyrin 5 and 15-positions is described. The synthesis and optical spectroscopy of five new compounds are reported: [5,15-bis[(4'-dimethylaminophenyl)ethynyl]-10,20-diphenylporphinato]zi nc(II), [5,15-bis[(4'-methoxyphenyl)ethynyl]-10,20-diphenylporphinato]zinc(II) , [5,15-bis[(phenyl)ethynyl]-10,20-diphenylporphinato]zinc(II), [5, 15-bis[(4'-fluorophenyl)ethynyl]-10,20-diphenylporphinato]zinc(II), and [5,15-bis[(4'-nitrophenyl)ethynyl]-10,20-diphenylporphinato]zinc(II). The X-ray structure of one of these complexes, [5,15-bis[(4'-fluorophenyl)ethynyl]-10,20-diphenylporphinato]zinc(II), is unusual in that it shows the arylethynyl-phenyl rings to be coplanar with the porphyrin macrocycle. This arrangement of aryl rings with respect to the porphyrin macrocycle underscores the fact that the steric barrier to rotation between the porphyrin and arylethynyl-phenyl aromatic systems has been removed and highlights the enhanced π-conjugative interactions responsible for the unusual electronic characteristics of these molecules. Electronic spectroscopy and electrochemistry of these systems evince the ability of this new porphyrin structural motif to modulate extensively chromophore electronic structure. ZINDO-determined (INDO-1 semiempirical parameters; CI level = 20) frontier orbital energies for the [5,15-bis[(aryl)ethynyl]-10,20-diphenylporphinato]zinc(II) complexes demonstrate that these properties derive from energetic differences between the porphyrin HOMO and HOMO-1 and a substantial splitting of the formerly degenerate porphyrin LUMO; these significant electronic perturbations (relative to simple (porphinato)zinc(II) complexes) are manifest in the fact that the low lying singlet excited states of these compounds are highly polarized.

AB - A new class of porphyrins in which intervening ethynyl moieties connect aryl groups to the porphyrin 5 and 15-positions is described. The synthesis and optical spectroscopy of five new compounds are reported: [5,15-bis[(4'-dimethylaminophenyl)ethynyl]-10,20-diphenylporphinato]zi nc(II), [5,15-bis[(4'-methoxyphenyl)ethynyl]-10,20-diphenylporphinato]zinc(II) , [5,15-bis[(phenyl)ethynyl]-10,20-diphenylporphinato]zinc(II), [5, 15-bis[(4'-fluorophenyl)ethynyl]-10,20-diphenylporphinato]zinc(II), and [5,15-bis[(4'-nitrophenyl)ethynyl]-10,20-diphenylporphinato]zinc(II). The X-ray structure of one of these complexes, [5,15-bis[(4'-fluorophenyl)ethynyl]-10,20-diphenylporphinato]zinc(II), is unusual in that it shows the arylethynyl-phenyl rings to be coplanar with the porphyrin macrocycle. This arrangement of aryl rings with respect to the porphyrin macrocycle underscores the fact that the steric barrier to rotation between the porphyrin and arylethynyl-phenyl aromatic systems has been removed and highlights the enhanced π-conjugative interactions responsible for the unusual electronic characteristics of these molecules. Electronic spectroscopy and electrochemistry of these systems evince the ability of this new porphyrin structural motif to modulate extensively chromophore electronic structure. ZINDO-determined (INDO-1 semiempirical parameters; CI level = 20) frontier orbital energies for the [5,15-bis[(aryl)ethynyl]-10,20-diphenylporphinato]zinc(II) complexes demonstrate that these properties derive from energetic differences between the porphyrin HOMO and HOMO-1 and a substantial splitting of the formerly degenerate porphyrin LUMO; these significant electronic perturbations (relative to simple (porphinato)zinc(II) complexes) are manifest in the fact that the low lying singlet excited states of these compounds are highly polarized.

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U2 - 10.1021/ja962403y

DO - 10.1021/ja962403y

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JO - Journal of the American Chemical Society

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