Redox switchable catenane

The tetrakis(DMPA-) salt of redox-switchable [2]catenane 214+ was also tested for its ability to form Langmuir films. In its tetracationic form, the n/A isotherm revealed (Fig. 32) an area per molecule of approximately 120 A2. This... 

Fig. 2A-C. Some examples of molecular information units A A solvent-switchable [2]caten-ane. B A redox-switchable [2]catenane. C A fulgide that undergoes a photoswitchable electrocyclization...

Figure 3.42 A model for a catenane-based molecular device. The two orientations of the catenane are redox-switchable by control of the copper oxidation state, (a) The tetrahedral Cu(i) complex and (b) the square-pyramidal Cu(ii) complex.

Fig. 34. Deposition of a monolayer of switchable [2]catenane 21-4DMPA is deposited onto a patterned polysilicon substrate, followed by condensation of orthogonal strips of Ti through a layer mask resulting in the formation of a network of junctions, each sandwiching a single layer of redox-active [2]catenanes...

The TTF molecule (Chart 1) is a u-delocalized system with readily accessible redox states. TTF. TTF, and TTF ". The reduced form ftmctions as a n-donor in FF interactions, but the oxidized forms have n-acceptor character. Incorporation of one TTF moiety into a donor cycle also containing 1.5-dioxynaphthalene, and catenation with a Z /5 -4,4 -bipyridinium n-acceptor cycle, leads to a switchable [2]catenane (Fig. 10). In the reduced TTF form (Fig. 10b), the TTF molecule, as donor, is sandwiched between the two 4,4 -bipyridinium acceptors. When oxidized (chemically or electrochemically). so that the TTF has a positive or 2+ charge (Fig. 10a), electrostatics cause rotational translation of one cycle relative to the other to displace the positive TTF to the outer section of the catenane. This switching is reversible. 

Stoddart et al. also incorporated a bistable [2]catenane (Figure 39) into macromolecules to form a side-chain poly[2]catenane (Figure 82). This poly[2]catenane could also behave as a molecular switch that can be addressed in an on or off state electrochemically by the virtue of the redox properties of the TTF moiety. Furthermore, the switching properties remain even in spherical aggregates. This stndy provides a good mechanically interlocked switchable polymeric scaffold for the construction of solid-state molecular electronic devices. 

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