DOI: 10.1021/acs.nanolett.8b00956

Here we present a study where what can be seen as a static modulation wave encompassing four successive arrays of interacting iodine atoms in crystalline 1,4-Bis((4′-(iodoethynyl)phenyl) ethynyl)bicyclo[2,2,2]octane rotors changes the structure from one-half molecule to three-and-a-half molecules in the asymmetric unit below a phase transition at 105 K. The remarkable finding is that the total ¹H spin–lattice relaxation rate, T₁^–1, of unprecedented complexity to date in molecular rotors, is the weighted sum of the relaxation rates of the four contributing rotors relaxation rates, each with distinguishable exchange frequencies reflecting Arrhenius parameters with different activation barriers (E_a) and attempt frequencies (τ_o^–1). This allows us to show in tandem with rotor-environment interaction energy calculations how the dynamics of molecular rotors are able to decode structural information from their surroundings with remarkable nanoscale precision.