Herein we report the synthesis of the highly stable crystalline carbazole-based rotor 3 with simultaneous rapid solid state internal rotation and good fluorescence emission. Single crystal and powder X-ray diffraction studies along with microscopy revealed a phase transition from a labile benzene solvate (phase I) to highly stable crystals (phase II) that feature fast intramolecular rotation in the megahertz regime at room temperature, according to variable temperature 2 H solid state NMR experiments using isotopically enriched analogues. In addition to the megahertz rotation within its crystals, this crystal phase II displays enhanced solid state fluorescence with a higher quantum yield of ϕ = 0.28, relative to the emission of this compound in THF solution (ϕ = 0.06). These two solid state properties are significantly different from shorter compounds 1 and 2 (static and nonemissive) included here for comparison purposes.

Induction of white light emission and chiroptical properties in 2D perovskites is achieved and controlled through the incorporation of chiral cations.

We report for the first time the high sorption properties of a molecular rotor with no permanent voids or channels in its crystal structure. Such crystalline phase originates from THF, DCM, or the irreversible desolvation of entrapped benzene molecules. From these, the benzene in its solvate form acts as rotation stopper, as supported by dynamic characterization using solid-state H NMR experiments. In the solvent-free form, the diffusion of small quantities of iodine vapors caused a significant change in the intramolecular rotation, increasing the known activation energy to rotation from 8.5 to 10.6 kcal mol. Notably, those results paved the way for the discovery of the high CO uptake (201.6 cm g at 196 K, under 1 atm) and acetone (5 wt %), a sorption property that was attributed to both, the restriction of the molecular rotation at low temperatures and the flexibility of the molecular axle made of conjugated p-(ethynylphenylene), surrounded by carbazole.

Liquid-like dynamics of a covalent 1,4-phenylene rotator have been unveiled in 1 with a brominated stator showing type-II halogen bonds. This singular rotation is favored by synergistic molecular changes in stacked molecules, according to VT solid state NMR, H T relaxometry and VT X-ray experiments of this highly crystalline compound.