Fine tuning of molecular rotor function in photochemical molecular switches
作者:Matthijs K.J. ter Wiel、Ben L. Feringa
DOI:10.1016/j.tet.2009.03.081
日期:2009.5
Molecular switches are used as scaffolds for the construction of controlled molecular rotors. The internal position of the switching entity in the molecule controls the dynamic behaviour of the rotor moiety in the molecule. Six new molecular motors with o-xylyl rotor moieties were prepared on the basis of an overcrowded alkene, and their dynamics were systematically studied by 2D EXSY NMR, Variation of the (hetero-)atoms in the upper and lower halves of the overcrowded alkene allows fine tuning of the rate of rotation of the o-xylyl rotor in the lower half of the molecule. For all rotors it was observed that the rotation barrier for the trans-isomer was higher than that of the corresponding cis-isomer. The results are analyzed and discussed in terms of differences in steric interactions in the presented system. (C) 2009 Elsevier Ltd. All rights reserved.
Photochemical and Thermal Isomerization Processes of a Chiral Auxiliary Based Donor–Acceptor Substituted Chiroptical Molecular Switch: Convergent Synthesis, Improved Resolution and Switching Properties
作者:Richard A. van Delden、Johannes H. Hurenkamp、Ben L. Feringa
DOI:10.1002/chem.200204660
日期:2003.6.16
of chiroptical molecular switch is presented where irradiation employing different wavelengths of light induces a reversible helix inversion of a sterically overcrowded alkene bearing a second chiral entity in the form of a stereogenic center present in a pyrrolidine unit. The additional stereogenic center in the chiral auxiliary group has a distinct influence on the switching selectivity of this system