Controlled orientation of metalloporphyrins and regioselective epoxidations in thermotropic liquid crystals

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Abstract

The orientation of a porphyrin molecule in a thermotropic nematic liquid crystal can be controlled by molecular design. Thus, the porphyrin plane of tetraphenylporphyrin (TPP) is aligned parallel to the director of a liquid crystal whereas a porphyrin with orthogonal substitution of mesogenic 4-n-butoxybiphenyl appendages (MesogenP) is oriented in a perpendicular conformation. The alignment was determined by time resolved EPR spectroscopy of the triplet state of the free base porphyrin. Manganese TPP and MesogenP porphyrins then were used as catalysts for the epoxidation of alkenes using iodosobenze as oxidant. Reaction yields and regioselectivity for enlongated substrates such as cis-stilbene and 4-vinylbiphenyl were dependent on the alignment of the alkene and its carbon-carbon double bond relative to the director and metalloporphyrin catalyst.

Original languageEnglish
Pages (from-to)33-37
Number of pages5
JournalMolecular Crystals and Liquid Crystals Science and Technology Section A: Molecular Crystals and Liquid Crystals
Volume240
Issue number1
DOIs
Publication statusPublished - Feb 1 1994

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Thermotropic liquid crystals
Metalloporphyrins
epoxidation
Epoxidation
Porphyrins
porphyrins
liquid crystals
appendages
Alkenes
alkenes
Olefins
Carbon
alignment
catalysts
Liquid Crystals
Stilbenes
Regioselectivity
Catalysts
stilbene
Nematic liquid crystals

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

Cite this

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abstract = "The orientation of a porphyrin molecule in a thermotropic nematic liquid crystal can be controlled by molecular design. Thus, the porphyrin plane of tetraphenylporphyrin (TPP) is aligned parallel to the director of a liquid crystal whereas a porphyrin with orthogonal substitution of mesogenic 4-n-butoxybiphenyl appendages (MesogenP) is oriented in a perpendicular conformation. The alignment was determined by time resolved EPR spectroscopy of the triplet state of the free base porphyrin. Manganese TPP and MesogenP porphyrins then were used as catalysts for the epoxidation of alkenes using iodosobenze as oxidant. Reaction yields and regioselectivity for enlongated substrates such as cis-stilbene and 4-vinylbiphenyl were dependent on the alignment of the alkene and its carbon-carbon double bond relative to the director and metalloporphyrin catalyst.",
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