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Control of the Helical Chirality of Enantiopure Sulfinyl (Z)-Azobenzene-Based Photoswitches

Authors

  • Irene Núñez,

    1. Departamento de Química Orgánica (Módulo-01), Universidad Autónoma de Madrid, Cantoblanco, 28049-Madrid (Spain)
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  • Dr. Estíbaliz Merino,

    1. Departamento de Química Orgánica (Módulo-01), Universidad Autónoma de Madrid, Cantoblanco, 28049-Madrid (Spain)
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  • Dr. Mercedes Lecea,

    1. Departamento de Química Orgánica (Módulo-01), Universidad Autónoma de Madrid, Cantoblanco, 28049-Madrid (Spain)
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  • Dr. Silvia Pieraccini,

    1. Dipartimento di Chimica Organica “A. Mangini”, Alma Mater Studiorum, Università di Bologna, Via San Giacomo 11, 40126 Bologna (Italy)
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  • Prof. Dr. Gian Piero Spada,

    1. Dipartimento di Chimica Organica “A. Mangini”, Alma Mater Studiorum, Università di Bologna, Via San Giacomo 11, 40126 Bologna (Italy)
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  • Prof. Dr. Carlo Rosini,

    1. Dipartimento di Chimica “A. Tamburro”, Università della Basilicata, 85100 Potenza (Italy)
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    • Deceased 2010.

  • Dr. Giuseppe Mazzeo,

    1. Dipartimento di Chimica “A. Tamburro”, Università della Basilicata, 85100 Potenza (Italy)
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  • Dr. María Ribagorda,

    Corresponding author
    1. Departamento de Química Orgánica (Módulo-01), Universidad Autónoma de Madrid, Cantoblanco, 28049-Madrid (Spain)
    • Departamento de Química Orgánica (Módulo-01), Universidad Autónoma de Madrid, Cantoblanco, 28049-Madrid (Spain)

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  • Prof. Dr. M. Carmen Carreño

    Corresponding author
    1. Departamento de Química Orgánica (Módulo-01), Universidad Autónoma de Madrid, Cantoblanco, 28049-Madrid (Spain)
    • Departamento de Química Orgánica (Módulo-01), Universidad Autónoma de Madrid, Cantoblanco, 28049-Madrid (Spain)

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Abstract

A new class of enantiopure ortho,ortho-disubstituted azobenzene photoswitches has been synthesized from (S)-2-(p-tolylsulfinyl)benzoquinone and arylhydrazines. The sulfoxide acts as a unidirectional controller of the helical chirality that arises in the Z isomer after photoisomerization. Highly congested E-azobenzenes 5 c showed two atropisomeric diastereoconformers in the solid state that converged upon irradiation into a unique Z isomer with defined helicity (M), as evident in the X-ray structure. The chiroptical properties of this three-state enantiopure switch can be externally tuned both photochemically and/or thermally. Theoretical CD spectra calculated by using time-dependent DFT methods support the existence of two atropoisomeric E isomers and only one Z isomer with (M) helicity. Complementary to the classical azobenzene-based switches, the photoswiching event is promoted under green/blue light and do not occur under UV irradiation.

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