Chemistry in motion--unidirectional rotating molecular motors.
Chemistry in motion--unidirectional rotating molecular motors.
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运动中的化学——单向旋转分子马达。
作者：
Christian P. Mandl;B. König
分子在不断运动，如果不是冻结在0K左右，但它们的布朗运动是随机的。克服这种随机化效应，并用人工系统在分子水平上产生定向运动仍然是一个挑战。这一领域的研究灵感来自于将发动机或马达的概念转移到分子水平的愿景。自然界中发现的定向过程说明了这一点：细胞分裂、细胞器移位和膜运输都依赖于定向运动，而复制、转录和翻译等过程需要以定向方式读取和复制编码的信息序列。宏观引擎和分子马达都将化学能、电能或光能转化为机械功，但它们的工作模式却截然不同。由于它们的尺寸，分子马达的工作能量必须仅略高于它们周围的热水浴的能量。它们是由布朗运动驱动的，其作用的关键是给这些无向过程指明方向。化学的作用是从所有可能的运动中选择一个方向，方法是降低这个定向运动相对于所有其他运动的能量分布。这使得这一运动优先发生。化学或光化学步骤为这些选择过程提供了动力。Leigh等人。最近报道了机械互锁分子转子的净相对单向旋转。[2]链烷体系(方案1)由一个更大的宏观组成--
Molecules are in constant motion, if not frozen around 0 K, but their Brownian motion is random. Overcoming this randomizing effect and generating directional motion at the molecular level with artificial systems is still a challenge. Research in this area is inspired by the vision of transferring the concept of an engine or a motor to the molecular level. That this is possible is illustrated by the directional processes found in nature: cell division, translocation of organelles, and membrane transport all rely on directional movement, while processes such as replication, transcription, and translation require encoded information sequences to be read and copied in a directional manner. Macroscopic engines and molecular motors both convert chemical, electrical, or light energy into mechanical work, yet their mode of operation is very different. Because of their dimensions molecular motors must operate at energies only slightly higher than those of the thermal bath surrounding them. They are actuated by Brownian motion and the key to their function is to give a direction to these undirected processes. Chemistry's role is to select one direction from all possible movements by lowering the energy profile of this directional movement compared to all the others. This makes this movement happen preferentially. Chemical or photochemical steps fuel these selection processes. Leigh et al. recently reported a net relative unidirectional circumrotation in a mechanically interlocked molecular rotor. The [2]catenane system (Scheme 1) consists of a larger macro-