Institut für Physikalische Chemie, Friedrich-Schiller-Universität Jena, Helmholtzweg 4, 07743 Germany.
Phys Chem Chem Phys. 2010 Oct 14;12(38):12279-89. doi: 10.1039/c0cp00324g. Epub 2010 Aug 16.
Chiral overcrowded alkenes are capable of unidirectional rotation via a series of cis-trans photochemical and helix-inversion thermal steps. Using a pseudo-random conformational search we have located different ground state minima belonging to the potential energy surface of two different overcrowded alkenes that function as molecular rotors. The transition states connecting the minima allow identifying different reaction pathways which are possible in the thermal helix-inversion steps. The mechanisms found for the two studied molecular rotors are different and provide a valuable insight into the conformational dynamics of the rotary cycle. While in one case the thermal step occurs via a single transition state, in the other, several intermediates are accessible. The associated energy barriers are in agreement with the experimental values, supporting the proposed mechanisms.
手性拥挤烯烃能够通过一系列顺反光化学和螺旋反转热步骤进行单向旋转。使用伪随机构象搜索，我们已经定位了属于两种不同的作为分子转子的拥挤烯烃的势能表面的不同基态最小值。连接这些最小值的过渡态允许识别在热螺旋反转步骤中可能发生的不同反应途径。为这两个研究的分子转子发现的机制是不同的，并为旋转循环的构象动力学提供了有价值的见解。在一种情况下，热步骤通过单个过渡态发生，而在另一种情况下，可获得多个中间体。相关的能量势垒与实验值一致，支持所提出的机制。
