Rotaxanes architectural features

By using an incrementally staged strategy, the architectural features of switchable rotaxane 9H3+ (Fig. 13.9)15 were incorporated into those of a previously investigated16 triply threaded two-component supramolecular bundle. The result was the construction of two-component molecular devices like 10H39+ (Fig. 13.11) that behave like nanoscale elevators. 17 Compound 10H39+, which measures about... 

One of the structural features seen in polyrotaxanes is the absence of any covalent binding between cyclic compounds and a linear polymeric chain capped with bulky end-groups at both terminals [1]. It looks like a necklace the cyclic compounds are mechanically locked by the linear polymeric chain. The cyclic compounds in a poly-rotaxane can slide and/or rotate along the axial polymeric chain if the polyrotaxane is soluble in a certain solvent. Furthermore, such mechanical locking between the cyclic compounds and the linear polymeric chain will be opened once one of the terminal bulky end-groups is cleaved by any external conditions. These characteristics are only observable in and specific to polyrotaxanes and are never seen in conventional polymeric architectures (Fig. 1). 

Finally, the anthracene-based [2] rotaxanes were studied in single layer OLED architecture [73, 74], The measurements revealed new features in electroluminescence spectra comparing to photoluminescence both in solid state and in solution. However, the origin of the phenomena is not still well understood and far to be exploited in applications. 

The cellular unit that is active toward the contraction of skeletal muscles, known as the sarcomere, is comprised of alternatively stacked filaments of the proteins actin and myosin. During muscle contraction, the protein filaments slide past each other as a result of a rowing action of the surface myosin heads (Figure 6.92a). Hence, an effective biomimetic approach would entail the design of a linear architecture that features sliding components that will respond to a chemical stimulus. This approach has recently been demonstrated with the design of a rotaxane molecule that exhibits redox-controlled contraction and extension of the molecular architecture, in response to a chemical or electrochemical stimulus (Figure 6.92b). ... 

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