Electrochemically controlled molecular motion

Figure 14.6 Schematic representation of electrochemically controlled molecular motion.

The electrochemical behavior of 14+ is particularly clean and interesting, since only the 4- and the 5-coordinate geometries can be obtained on translating the metal-complexed ring from the phen site to the terpy site)841 The electrochemically induced molecular motions (square scheme1851), similar to those represented in Figure 10 but now involving stopped compounds, can be monitored by cyclic voltammetry (CV) and controlled potential electrolysis experiments)851... 

Fig. 5 Controlled molecular motion in rotaxanes light-driven shifting of the wheel along the rotaxane axle (top) and contraction of a molecular muscle stimulated hy electrochemical Cu(I)-Cu(II) interconversion (bottom).

Figure 2.35. Diagram of the molecular motions in copper(I)-complexed [2]-rotaxane 101 controlled by the redox state dependence of the stereoelectronic requirements of Cu. Cu(I) and Cu(II) are represented by black and white circles, respectively. Chelating sites are represented by thick lines. Initially, the string coordinates Cu(I) together with the bidentate site of the macrocycle in a tetrahedral geometry, affording the state 101(4). Electrochemical oxidation of Cu(I) to Cu(II) produces the state 101+(4), which slowly converts into the state 101+(5) after rotation of the Cu(II)-complexed macrocycle. The cycle is completed by reduction of Cu(II), which produces the state 101(5), converting to the initial state by back motion of the Cu(I)-complexed macrocycle.

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