Discotic liquid crystalline hexabenzocoronenes carrying chiral and racemic branched alkyl chains: Supramolecular engineering and improved synthetic methods

Andreas Fechtenkötter; Natalia Tchebotareva; Mark Watson; Klaus Müllen

doi:10.1016/S0040-4020(01)00252-6

Discotic liquid crystalline hexabenzocoronenes carrying chiral and racemic branched alkyl chains: Supramolecular engineering and improved synthetic methods

Andreas Fechtenkötter, Natalia Tchebotareva, Mark Watson, Klaus Müllen

Chemistry

Research output: Contribution to journal › Article › peer-review

148 Scopus citations

Abstract

In this paper we present the synthesis and characterization of three different thermotropic liquid crystalline derivatives of hexabenzocoronene (HBC), substituted at the periphery by six chiral or racemic branched (3,7-dimethyloctanyl) chains, namely the chiral 5a, racemic 5b, and mono-bromo functionalized 18 carrying five alkyl chains. Improved methods for synthesis of HBC precursors, largely relying on transition-metal catalyzed coupling reactions, are also described. Solubility and processability are increased while the thermal K→D_H transitions are shifted to lower temperatures, relative to analogous HBCs carrying n-alkyl chains. In case of substitution with a chiral branched alkyl chain, 5a, strong signals have been recorded by means of circular dichroism spectroscopy. All new compounds were characterized by ¹H, ¹³C NMR, and UV-Vis spectroscopy, and FD-MS. Preliminary mesophase characterization is carried out by differential scanning calorimetry (DSC) and polarized light microscopy. In the course of the DSC experiments, optically pure and racemic HBC derivatives were compared.

Original language	English
Pages (from-to)	3769-3783
Number of pages	15
Journal	Tetrahedron
Volume	57
Issue number	17
DOIs	https://doi.org/10.1016/S0040-4020(01)00252-6
State	Published - Apr 23 2001

Bibliographical note

Funding Information:
This research was supported by the TMR European Research Program through the SISITOMAS project and the Volkswagen-Stiftung. We thank Petra Räder for conducting ‘last-minute’ DSC and TGA experiments. The help and advice from Professor Dr E. W. Meijer and his group, especially from Luc Brunsveld, during the CD experiments is gratefully acknowledged.

Funding

This research was supported by the TMR European Research Program through the SISITOMAS project and the Volkswagen-Stiftung. We thank Petra Räder for conducting ‘last-minute’ DSC and TGA experiments. The help and advice from Professor Dr E. W. Meijer and his group, especially from Luc Brunsveld, during the CD experiments is gratefully acknowledged.

Funders	Funder number
Volkswagen-Stiftung

Keywords

Chiral mesophase
Discotic liquid crystals
Hexabenzocoronenes
Polyaromatic hydrocarbons (PAH)

ASJC Scopus subject areas

Biochemistry
Drug Discovery
Organic Chemistry

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10.1016/S0040-4020(01)00252-6

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title = "Discotic liquid crystalline hexabenzocoronenes carrying chiral and racemic branched alkyl chains: Supramolecular engineering and improved synthetic methods",

abstract = "In this paper we present the synthesis and characterization of three different thermotropic liquid crystalline derivatives of hexabenzocoronene (HBC), substituted at the periphery by six chiral or racemic branched (3,7-dimethyloctanyl) chains, namely the chiral 5a, racemic 5b, and mono-bromo functionalized 18 carrying five alkyl chains. Improved methods for synthesis of HBC precursors, largely relying on transition-metal catalyzed coupling reactions, are also described. Solubility and processability are increased while the thermal K→DH transitions are shifted to lower temperatures, relative to analogous HBCs carrying n-alkyl chains. In case of substitution with a chiral branched alkyl chain, 5a, strong signals have been recorded by means of circular dichroism spectroscopy. All new compounds were characterized by 1H, 13C NMR, and UV-Vis spectroscopy, and FD-MS. Preliminary mesophase characterization is carried out by differential scanning calorimetry (DSC) and polarized light microscopy. In the course of the DSC experiments, optically pure and racemic HBC derivatives were compared.",

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note = "Funding Information: This research was supported by the TMR European Research Program through the SISITOMAS project and the Volkswagen-Stiftung. We thank Petra R{\"a}der for conducting {\textquoteleft}last-minute{\textquoteright} DSC and TGA experiments. The help and advice from Professor Dr E. W. Meijer and his group, especially from Luc Brunsveld, during the CD experiments is gratefully acknowledged. ",

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AU - Müllen, Klaus

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N2 - In this paper we present the synthesis and characterization of three different thermotropic liquid crystalline derivatives of hexabenzocoronene (HBC), substituted at the periphery by six chiral or racemic branched (3,7-dimethyloctanyl) chains, namely the chiral 5a, racemic 5b, and mono-bromo functionalized 18 carrying five alkyl chains. Improved methods for synthesis of HBC precursors, largely relying on transition-metal catalyzed coupling reactions, are also described. Solubility and processability are increased while the thermal K→DH transitions are shifted to lower temperatures, relative to analogous HBCs carrying n-alkyl chains. In case of substitution with a chiral branched alkyl chain, 5a, strong signals have been recorded by means of circular dichroism spectroscopy. All new compounds were characterized by 1H, 13C NMR, and UV-Vis spectroscopy, and FD-MS. Preliminary mesophase characterization is carried out by differential scanning calorimetry (DSC) and polarized light microscopy. In the course of the DSC experiments, optically pure and racemic HBC derivatives were compared.

AB - In this paper we present the synthesis and characterization of three different thermotropic liquid crystalline derivatives of hexabenzocoronene (HBC), substituted at the periphery by six chiral or racemic branched (3,7-dimethyloctanyl) chains, namely the chiral 5a, racemic 5b, and mono-bromo functionalized 18 carrying five alkyl chains. Improved methods for synthesis of HBC precursors, largely relying on transition-metal catalyzed coupling reactions, are also described. Solubility and processability are increased while the thermal K→DH transitions are shifted to lower temperatures, relative to analogous HBCs carrying n-alkyl chains. In case of substitution with a chiral branched alkyl chain, 5a, strong signals have been recorded by means of circular dichroism spectroscopy. All new compounds were characterized by 1H, 13C NMR, and UV-Vis spectroscopy, and FD-MS. Preliminary mesophase characterization is carried out by differential scanning calorimetry (DSC) and polarized light microscopy. In the course of the DSC experiments, optically pure and racemic HBC derivatives were compared.

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Discotic liquid crystalline hexabenzocoronenes carrying chiral and racemic branched alkyl chains: Supramolecular engineering and improved synthetic methods

Abstract

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Funding

Keywords

ASJC Scopus subject areas

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