Recent developments in synthetic molecular motors and pumps have sprung from a remarkable confluence of experiment and theory. Synthetic accomplishments have facilitated the ability to design and create molecules, many of them featuring mechanically bonded components, to carry out specific functions in their environment—walking along a polymeric track, unidirectional circling of one ring about another, synthesizing stereoisomers according to an external protocol, or pumping rings onto a long rod-like molecule to form and maintain high-energy, complex, nonequilibrium structures from simpler antecedents. Progress in the theory of nanoscale stochastic thermodynamics, specifically the generalization and extension of the principle of microscopic reversibility to the single-molecule regime, has enhanced the understanding of the design requirements for achieving strong unidirectional motion and high efficiency of these synthetic molecular machines for harnessing energy from external fluctuations to carry out mechanical and/or chemical functions in their environment. A key insight is that the interaction between the fluctuations and the transition state energies plays a central role in determining the steady-state concentrations. Kinetic asymmetry, a requirement for stochastic adaptation, occurs when there is an imbalance in the effect of the fluctuations on the forward and reverse rate constants. Because of strong viscosity, the motions of the machine can be viewed as mechanical equilibrium processes where mechanical resonances are simply impossible but where the probability distributions for the state occupancies and trajectories are very different from those that would be expected at thermodynamic equilibrium.

在实验和理论的显着融合中，合成分子电动机和泵的最新发展如雨后春笋般涌现。合成技术的成就促进了设计和创造分子的能力，其中许多分子具有机械结合的成分，可以在其环境中执行特定功能-沿着聚合物轨道行走，一个环绕另一环单向环绕，根据外部规程合成立体异构体或将环泵送到长的棒状分子上，以根据较简单的先例形成并维持高能，复杂，不平衡的结构。纳米级随机热力学理论的进展，特别是微观可逆性原理对单分子体系的推广和扩展，对这些合成分子机器实现强大的单向运动和高效率以利用外部波动的能量来在其环境中执行机械和/或化学功能的设计要求的理解得到了加深理解。一个关键的见解是，波动与过渡态能量之间的相互作用在确定稳态浓度中起着核心作用。当波动对正向和反向速率常数的影响不平衡时，就会发生动态不对称，这是随机适应的要求。由于黏性强