A two-stage molecular retractable cable featuring push-button and rotary two-way switching modes.

A molecular cage based [2]rotaxane is reported in which the linear thread component can be elongated and contracted in a stepwise manner, mimicking a two-stage retractable cable that can be operated in both push-button (free-selection) and rotary (continuous-change) modes, depending on the choice of reagents.

Observation of face-to-face host-guest associated states prior to threading of dialkylammonium ions into the DB24C8-like openings of a molecular cage.

The threading of bis(dialkylammonium) ions through the DB24C8-like openings of a molecular cage proceeds through a stepwise mechanism: formation of a face-to-face complex between the NH2(+) centers and the crown ether, significant dissociation of this complex, and passage of the terminus of the cation through the macrocycle.

Weakly associated TFPB anions are superior to PF6 anions when preparing (pseudo)rotaxanes from crown ethers and secondary dialkylammonium ions.

Making the right choice: Tetrakis(3,5-trifluoromethylphenyl)borate (TFPB) counter anions can facilitate the threading of dibenzylammonium (DBA(+)) ions through macrocycles in cases where the corresponding PF(6)(-) salts fail to exhibit complexation.

A molecular cage-based [2]rotaxane that behaves as a molecular muscle.

We report a molecular cage-based [2]rotaxane that functions as an artificial molecular muscle through the control of the addition and removal of fluoride anions. The percentage change in molecular length of the [2]rotaxane is about 36% between the stretched and contracted states, which is larger than the percentage change (approximately 27%) in human muscle.