The solid state is typically not well suited to sustaining fast molecular motion, but in recent years a variety of molecular machines, switches and rotors have been successfully engineered within porous crystals and on surfaces. Here we show a fast-rotating molecular rotor within the bicyclopentane–dicarboxylate struts of a zinc-based metal–organic framework—the carboxylate groups anchored to the metal clusters act as an axle while the bicyclic unit is free to rotate. The three-fold bipyramidal symmetry of the rotator conflicts with the four-fold symmetry of the struts within the cubic crystal cell of the zinc metal–organic framework. This frustrates the formation of stable conformations, allowing for the continuous, unidirectional, hyperfast rotation of the bicyclic units with an energy barrier of 6.2 cal mol⁻¹ and a high frequency persistent for several turns even at very low temperatures (10¹⁰ Hz below 2 K). Using zirconium instead of zinc led to a different metal cluster–carboxylate coordination arrangement in the resulting metal–organic framework, and much slower rotation of the bicyclic units.

固态通常不太适合维持快速的分子运动，但是近年来，已经成功地在多孔晶体内和表面上成功设计了各种分子机器，开关和转子。在这里，我们显示了一个基于锌的金属-有机骨架的双环戊烷-二羧酸酯支链中的快速旋转分子转子-锚定在金属簇上的羧酸酯基团充当轴，而双环单元可自由旋转。转子的三重双锥对称与锌金属-有机骨架的立方晶格内的支撑杆的四重对称冲突。这阻碍了稳定构象的形成，允许双环单元连续，单向，超快旋转，能量垒为6.2 cal mol ^-1甚至在非常低的温度（ 低于2 K的10 ¹⁰ Hz）下，高频也能持续旋转几圈。用锆代替锌会导致金属-有机骨架中金属簇-羧酸盐的配位方式不同，并且双环单元的旋转要慢得多。