Anisotropic Thermal Expansion as the Source of Macroscopic and Molecular Scale Motion in Phosphorescent Amphidynamic Crystals
Herein we report a crystalline molecular rotor with rotationally modulated triplet emission that displays macroscopic dynamics in the form of crystal moving and/or jumping, also known as salient effects. Molecular rotor 2 with a central 1,4‐diethynyl‐2,3‐difluorophenylene rotator linked to two gold(I) nodes, crystalizes as infinite 1D chains through intermolecular gold(I)–gold(I) interactions. The rotational motion changes the orientation of the central phenylene, changing the electronic communication between adjacent chromophores, and thus the emission intensities. Crystals of 2 showed the large and reversible thermal expansion/compression anisotropy, which accounts for 1) a nonlinear Arrhenius behavior in molecular‐level rotational dynamics, which correlates with 2) changes in emission, and determines 3) the macroscopic crystal motion. A molecular rotor analogue 3 has properties similar to those of 2, suggesting a generalized way to control mechanical properties at molecular and macroscopic scales.