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Bond Rotation

The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform

Bruce P Branchaud – 1st expert on this subject based on the ideXlab platform

  • 180° Unidirectional Bond Rotation in a Biaryl Lactone Artificial Molecular Motor Prototype
    Organic Letters, 2006
    Co-Authors: Bart J. Dahl And, Bruce P Branchaud

    Abstract:

    A bifunctional biaryl lactone has been synthesized that should be capable of iterative unidirectional aryl−aryl Bond Rotation via:  (1) a diastereoselective lactone ring opening, (S)-1 to (P,S)-2 or (M,S)-2; (2) a chemoselective lactonization, (P,S)-2 or (M,S)-2 to (S)-3; and (3) a chemoselective hydrolysis, (S)-3 to (S)-1. Preliminary results of a racemic sample have indicated unidirectional 180° Rotation with very high directional selectivity per individual artificial molecular motor molecule through the first two steps of this sequence.

  • 180 unidirectional Bond Rotation in a biaryl lactone artificial molecular motor prototype
    Organic Letters, 2006
    Co-Authors: Bruce P Branchaud

    Abstract:

    A bifunctional biaryl lactone has been synthesized that should be capable of iterative unidirectional aryl−aryl Bond Rotation via:  (1) a diastereoselective lactone ring opening, (S)-1 to (P,S)-2 or (M,S)-2; (2) a chemoselective lactonization, (P,S)-2 or (M,S)-2 to (S)-3; and (3) a chemoselective hydrolysis, (S)-3 to (S)-1. Preliminary results of a racemic sample have indicated unidirectional 180° Rotation with very high directional selectivity per individual artificial molecular motor molecule through the first two steps of this sequence.

  • net directed 180 aryl aryl Bond Rotation in a prototypical achiral biaryl lactone synthetic molecular motor
    Tetrahedron Letters, 2005
    Co-Authors: Bart J Dahl, Bruce P Branchaud

    Abstract:

    Abstract Net directed 180° Bond Rotation was achieved through diastereoselective ring-opening reactions in an achiral biaryl lactone using a chiral nucleophile followed by re-lactonization. The efficiency of the directed Bond Rotation has been determined by HPLC–MS to be 50% and 20% with two different chiral nucleophiles. These results demonstrate the potential for a prototype of a chemically driven synthetic molecular motor which has the advantages of both simplicity and flexibility in operation and is the first example of the use of a chiral auxiliary to induce transient axial chirality resulting in net directed Bond Rotation.

Jeanmarie Lehn – 2nd expert on this subject based on the ideXlab platform

  • internal c c Bond Rotation in photoisomers of α bisimines a light responsive two step molecular speed regulator based on double imine photoswitching
    European Journal of Organic Chemistry, 2016
    Co-Authors: Lutz Greb, Andreas Eichhofer, Jeanmarie Lehn

    Abstract:

    Benzil-based α-bisimines are implemented as photoswitches for the construction of a speed-regulating molecular device, in which, by application of light, three different states may be addressed, showing distinct frequencies of internal C–C Bond Rotation, spanning 12 orders of magnitude. Bond Rotation barriers were determined experimentally and elucidated by DFT-methods.

  • Internal C–C Bond Rotation in Photoisomers of α-Bisimines: a Light-Responsive Two-Step Molecular Speed Regulator Based on Double Imine Photoswitching
    European Journal of Organic Chemistry, 2016
    Co-Authors: Lutz Greb, Andreas Eichhofer, Jeanmarie Lehn

    Abstract:

    Benzil-based α-bisimines are implemented as photoswitches for the construction of a speed-regulating molecular device, in which, by application of light, three different states may be addressed, showing distinct frequencies of internal C–C Bond Rotation, spanning 12 orders of magnitude. Bond Rotation barriers were determined experimentally and elucidated by DFT-methods.

  • synthetic molecular motors thermal n inversion and directional photoinduced cn Bond Rotation of camphorquinone imines
    Angewandte Chemie, 2015
    Co-Authors: Lutz Greb, Andreas Eichhofer, Jeanmarie Lehn

    Abstract:

    The thermal and photochemical E/Z isomerization of camphorquinone-derived imines was studied by a combination of kinetic, structural, and computational methods. The thermal isomerization proceeds by linear N inversion, whereas the photoinduced process occurs through C=N Bond Rotation with preferred directionality as a result of diastereoisomerism. Thereby, these imines are arguably the simplest example of synthetic molecular motors. The generality of the orthogonal trajectories of the thermal and photochemical pathways allows for the postulation that every suitable chiral imine qualifies, in principle, as a molecular motor driven by light or heat.

Yufen Zhao – 3rd expert on this subject based on the ideXlab platform

  • investigation of the c n Bond Rotation of spirophosphorane carbamates by dynamic nmr and dft calculation
    Tetrahedron, 2015
    Co-Authors: Pei Zhao, Yufen Zhao, Yanyan Wang, Miaomiao Peng

    Abstract:

    Abstract Spirophosphorane carbamates are a new type of pentacoordinate phosphorus compounds. In order to explore internal Rotation, the dynamic 1H NMR, 31P NMR and molecular theory calculations were employed to investigate the Rotation barriers of the N–C( O) Bond of symmetrical and asymmetrical spirophosphorane carbamates. The Gibbs free activation, ΔG≠, was calculated by Eyring equation. The results showed that the Rotation barriers of spirophosphorane carbamates were about 16–18 kcal/mol, and the Rotation isomers coexisted at room temperature. Moreover, it was found that the benzyl group attached to amide nitrogen increased the C–N Bond Rotation barriers of spirophosphorane carbamates. Furthermore, the preferred conformation of spirophosphorane carbamates was presumed by density functional theory (DFT), and the conformation of solid state were also confirmed by X-ray diffraction analysis.

  • Investigation of the C–N Bond Rotation of spirophosphorane carbamates by dynamic NMR and DFT calculation
    Tetrahedron, 2015
    Co-Authors: Pei Zhao, Yanyan Wang, Miaomiao Peng, Yufen Zhao

    Abstract:

    Abstract Spirophosphorane carbamates are a new type of pentacoordinate phosphorus compounds. In order to explore internal Rotation, the dynamic 1H NMR, 31P NMR and molecular theory calculations were employed to investigate the Rotation barriers of the N–C( O) Bond of symmetrical and asymmetrical spirophosphorane carbamates. The Gibbs free activation, ΔG≠, was calculated by Eyring equation. The results showed that the Rotation barriers of spirophosphorane carbamates were about 16–18 kcal/mol, and the Rotation isomers coexisted at room temperature. Moreover, it was found that the benzyl group attached to amide nitrogen increased the C–N Bond Rotation barriers of spirophosphorane carbamates. Furthermore, the preferred conformation of spirophosphorane carbamates was presumed by density functional theory (DFT), and the conformation of solid state were also confirmed by X-ray diffraction analysis.