Reversibly photoswitchable phenylazo‐3,5‐dimethylisoxazole and 37 aryl‐substituted derivatives were synthesized. Excellent photoswitching ability of these compounds in solution and the solid state was demonstrated. Through kinetics studies by means of NMR spectroscopy, high Z‐isomer stability was demonstrated. Interestingly, the majority of the derivatives showed light‐induced contrasting color changes in solution and the solid state. Besides, many of the derivatives exhibit partial phase transition upon UV irradiation. The highlight of this class of photoswitches is the reversible light‐induced phase transition between solid and liquid phases in the parent compound, which can be used in patterned crystallization. These results show that this new class of azoheteroarene based photoswitches has opportunities to be useful in various domains.

A single-event microkinetic (SEMK) model was developed for the conversion of methanol to olefins (MTO) and used in the assessment of experimental data obtained on H-ZSM-5 with a Si/Al ratio of 200. The experiments were performed at temperatures from 643 to 753 K, space times between 0.5 and 6.5 kgcat·s mol–1 and at atmospheric pressure. Dimethyl ether (DME) and primary olefins formation through aromatic hydrocarbon pool and higher olefins formation via the alkene homologation cycle, was implemented in terms of elementary steps. The single-event concept, in combination with thermodynamic constraints allowed a significant reduction of the number of adjustable parameters. A further reduction was achieved by calculation of the single-event pre-exponential factors based on statistical thermodynamics. Physicochemical constraints along with Boudart’s criteria were used to limit the parameter space. Twenty one activation energies of kinetically significant reaction families and eight protonation enthalpies corresponding to methanol, DME and olefins were estimated via regression to the experimental data. The SEMK model well describes the product distribution, relying on model parameters with a precise physical meaning. The trends in activation energies obtained, are as could be expected from the considered reaction family, and the type of carbenium ions involved as reactant and product. Olefin protonation enthalpies decrease from −11.2 kJ/mol for ethene to −70.3 kJ/mol for heptene. A reaction path analysis established that ethene originates exclusively from the aromatic hydrocarbon pool, while propene is formed both via the aromatic hydrocarbon pool and the alkene homologation cycle.

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Reversibly photoswitchable discotic liquid crystals (DLCs) with no change in columnar assembly.