The Experts below are selected from a list of 7530 Experts worldwide ranked by ideXlab platform

Michael B Hursthouse - One of the best experts on this subject based on the ideXlab platform.

  • ring contraction during the 6π electrocyclisation of naphthopyran valence tautomers
    Organic and Biomolecular Chemistry, 2008
    Co-Authors: Christopher D Gabbutt, Mark B Heron, Suresh B Kolla, Colin A Kilner, Simon J Coles, Peter N Horton, Michael B Hursthouse
    Abstract:

    The thermal and photochemical ring-opening of spiro(3H-naphtho[2,1-b]pyran-3,9′-thioxanthene-10,10-dioxide) 3 results in the facile ring-contraction to 9-(naphtho[2,1-b]furan-2-yl)-9H-thioxanthene-10,10-dioxide 6. Similar behaviour is displayed by the Isomeric spiro(2H-naphtho[1,2-b]pyran-2,9′-thioxanthene-10,10-dioxide) 9 affording 9-(naphtho[1,2-b]furan-2-yl)-9H-thioxanthene-10,10-dioxide 12, though more severe reaction conditions were required. The comparative ease of this rearrangement for the Isomers 3 and 9 was rationalised on the basis of the Relative Isomer populations of the ring-opened naphthopyrans. The rearrangement of simple mono- and bis-methylsulfonylphenyl substituted photochromic naphthopyrans 18, 20 was examined; the former failed to rearrange whereas the latter could be induced to rearrange only under prolonged UV irradiation. The photochromism of diastereoIsomerically pure sulfoxides derived from the oxidation of spiro(3H-naphtho[2,1-b]pyran-3,9′-thioxanthene) 2a and spiro(2H-naphtho[1,2-b]pyran-2,9′-thioxanthene) 2b resulted in conversion to the most thermodynamically stable trans-Isomer in each case.

Henryk A Witek - One of the best experts on this subject based on the ideXlab platform.

  • Relative Isomer abundance of fullerenes and carbon nanotubes correlates with kinetic stability
    Physical Review Letters, 2011
    Co-Authors: A S Fedorov, Dmitry A Fedorov, A A Kuzubov, Pavel V Avramov, Yoshifumi Nishimura, Stephan Irle, Henryk A Witek
    Abstract:

    A methodology to evaluate the kinetic stability of carbon nanostructures is presented based on the assumption of the independent and random nature of thermal vibrations. The kinetic stability is directly correlated to the cleavage probability for the weakest bond of a given nanostructure. The application of the presented method to fullerenes and carbon nanotubes yields clear correlation to their experimentally observed Relative Isomer abundances. The general and simple formulation of the method ensures its applicability to other nanostructures for which formation is controlled by kinetic factors.

Pavel V Avramov - One of the best experts on this subject based on the ideXlab platform.

  • Relative Isomer abundance of fullerenes and carbon nanotubes correlates with kinetic stability
    Physical Review Letters, 2011
    Co-Authors: A S Fedorov, Dmitry A Fedorov, A A Kuzubov, Pavel V Avramov, Yoshifumi Nishimura, Stephan Irle, Henryk A Witek
    Abstract:

    A methodology to evaluate the kinetic stability of carbon nanostructures is presented based on the assumption of the independent and random nature of thermal vibrations. The kinetic stability is directly correlated to the cleavage probability for the weakest bond of a given nanostructure. The application of the presented method to fullerenes and carbon nanotubes yields clear correlation to their experimentally observed Relative Isomer abundances. The general and simple formulation of the method ensures its applicability to other nanostructures for which formation is controlled by kinetic factors.

Christopher D Gabbutt - One of the best experts on this subject based on the ideXlab platform.

  • ring contraction during the 6π electrocyclisation of naphthopyran valence tautomers
    Organic and Biomolecular Chemistry, 2008
    Co-Authors: Christopher D Gabbutt, Mark B Heron, Suresh B Kolla, Colin A Kilner, Simon J Coles, Peter N Horton, Michael B Hursthouse
    Abstract:

    The thermal and photochemical ring-opening of spiro(3H-naphtho[2,1-b]pyran-3,9′-thioxanthene-10,10-dioxide) 3 results in the facile ring-contraction to 9-(naphtho[2,1-b]furan-2-yl)-9H-thioxanthene-10,10-dioxide 6. Similar behaviour is displayed by the Isomeric spiro(2H-naphtho[1,2-b]pyran-2,9′-thioxanthene-10,10-dioxide) 9 affording 9-(naphtho[1,2-b]furan-2-yl)-9H-thioxanthene-10,10-dioxide 12, though more severe reaction conditions were required. The comparative ease of this rearrangement for the Isomers 3 and 9 was rationalised on the basis of the Relative Isomer populations of the ring-opened naphthopyrans. The rearrangement of simple mono- and bis-methylsulfonylphenyl substituted photochromic naphthopyrans 18, 20 was examined; the former failed to rearrange whereas the latter could be induced to rearrange only under prolonged UV irradiation. The photochromism of diastereoIsomerically pure sulfoxides derived from the oxidation of spiro(3H-naphtho[2,1-b]pyran-3,9′-thioxanthene) 2a and spiro(2H-naphtho[1,2-b]pyran-2,9′-thioxanthene) 2b resulted in conversion to the most thermodynamically stable trans-Isomer in each case.

A S Fedorov - One of the best experts on this subject based on the ideXlab platform.

  • Relative Isomer abundance of fullerenes and carbon nanotubes correlates with kinetic stability
    Physical Review Letters, 2011
    Co-Authors: A S Fedorov, Dmitry A Fedorov, A A Kuzubov, Pavel V Avramov, Yoshifumi Nishimura, Stephan Irle, Henryk A Witek
    Abstract:

    A methodology to evaluate the kinetic stability of carbon nanostructures is presented based on the assumption of the independent and random nature of thermal vibrations. The kinetic stability is directly correlated to the cleavage probability for the weakest bond of a given nanostructure. The application of the presented method to fullerenes and carbon nanotubes yields clear correlation to their experimentally observed Relative Isomer abundances. The general and simple formulation of the method ensures its applicability to other nanostructures for which formation is controlled by kinetic factors.