A new unidirectional light-driven molecular motor suitable for host-guest surface inclusion complexes with tris(o-phenylene)cyclotriphosphazene (TPP) was synthesized. The motor molecules formed regular two-dimensional trigonal arrays covering the large facets of disc-shaped TPP nanocrystals. Photochemical and thermal isomerization studies demonstrated that the light-driven rotation of the anchored motors is similar to that observed in solution and is not compromised neither by either the surface confinement or the density of surface coverage (50 vs 100%).

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 H spin-lattice relaxation rate, T, 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) and attempt frequencies (τ). 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.

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