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The preparation of pseudorotaxanes containing a ferrocene-substituted ammonium axis from chemical and electrochemical reactions is reported. Electrochemical oxidation coupled with the transfer of a hydrogen atom from a hydrogen source provides the pseudotaxanes with DB24C8 and electron transfer between the Fe and N atoms plays an important role for formation of the dialkylammonium from the dialkylamine group.

The novel reaction of an axis molecule containing a kerosene moiety, which is activated by an electrochemical stimulus and forms a pseudorotaxane with a crown ether, is reported. The reaction takes place by electrochemical oxidation and is completed rapidly in the presence of a suitable hydrogen atom source.

The transition-metal-catalyzed reaction involving formation of a C-C bond from a specific C-H bond is a major challenge in organic synthesis. The Pd/Cu-catalyzed C-H bond substitution reaction of thiazole (a) in the presence of tetrabutylammonium fluoride (TABF) as an activator takes place regioselectively under mild conditions.

This paper presents a pseudorotaxane that acts as a thermally driven molecular switch in the single-crystal state. Crystals of the cationic pseudorotaxane consisting of dibenzo[24]crown-8 (DB24C8) and N-(xylylammonium)-methylferrocene as the cyclic and axle component molecules respectively undergo crystalline-phase transition at 128 °C with heating and 116 °C with cooling according to differential-scanning-calorimetry measurements. X-ray crystallographic analyses revealed that the phase transition was accompanied by rotation of the 4-methylphenyl group of the axle component molecule and a simultaneous shift in the position of the PF-6 counteranion. Crystalline phase transition changes the conformation and position of the DB24C8 molecule relative to the ammonium cation partially; the interaction between the cyclic component and the PF-6 anion in the crystal changes to a greater extent. Moreover there are changes in the vibration angle (θ) and birefringence (Δn) on the (001) face of the crystal transitionally; θ is rotated by +12° and Δn is decreased from 0.070 to 0.059 upon heating across the phase transition temperature. The phase transition and accompanying change in the optical properties of the crystal occur reversibly and repeatedly upon heating and cooling processes. The switching rotation of the aromatic plane of the molecule induces a change in the optical anisotropy of the crystal which is regarded as a demonstration of a new type of optical crystal. Partial replacement of the PF-6 anion with the bulkier AsF-6 anion forms crystals with similar crystallographic parameters. An increase in the AsF-6 content decreases the reversible-phase-transition temperature gradually down to 99 °C (Tend) and 68 °C (Texo) ([AsF-6]:[PF-6] = 0.4:0.6). [ABSTRACT FROM AUTHOR]