Nishiyama Yohei, Inagaki Yusuke, Yamaguchi Kentaro, Setaka Wataru
Division of Applied Chemistry, Faculty of Urban Environmental Sciences, Tokyo Metropolitan University , Hachioji, Tokyo 192-0397, Japan.
Faculty of Pharmaceutical Sciences at Kagawa Campus, Tokushima Bunri University , Sanuki, Kagawa 769-2193, Japan.
J Org Chem. 2015 Oct 16;80(20):9959-66. doi: 10.1021/acs.joc.5b01489. Epub 2015 Sep 30.
Macrocage molecules with a bridged π-electron system have been reported as molecular gyrotops in which the π-electron system can rotate within the cage. We recently reported the dynamics of the rotor in solution using 1,4-naphthalenediyl-bridged molecular gyrotops, which consist of cages formed of three C14, C16, or C18 chains. In this work, we synthesized novel gyrotops with C15 and C17 chains and systematically investigated the activation energies for the rotation of the rotor in solution. The activation energies for rotation in solution were found to decrease with increasing size of the cage. Therefore, a rotational barrier can be designed by adjusting the length of the side chains in these molecular gyrotops. Additionally, these gyrotops were fluorescent in solution; the quantum yields and lifetimes of the fluorescence were investigated. However, these properties were not influenced by the chain length owing to a large difference in time scale between fluorescence (10(-8)-10(-9) s) and the rotational dynamics inside the cage (10°-10(-5) s).
据报道，具有桥连π电子体系的大环分子作为分子陀螺，其中π电子体系可在笼内旋转。我们最近报道了使用由三条C14、C16或C18链构成笼的1,4 - 萘二基桥连分子陀螺研究溶液中转子的动力学。在这项工作中，我们合成了具有C15和C17链的新型陀螺，并系统地研究了溶液中转子旋转的活化能。发现溶液中旋转的活化能随笼尺寸的增加而降低。因此，可通过调节这些分子陀螺中侧链的长度来设计旋转势垒。此外，这些陀螺在溶液中具有荧光；研究了荧光的量子产率和寿命。然而，由于荧光（10^(-8)-10^(-9) s）与笼内旋转动力学（10°-10^(-5) s）在时间尺度上存在很大差异，这些性质不受链长的影响。
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