Cyclobis CBPQT

The position of the macrocycle on the thread of a rotaxane can be controlled through repulsive electrostatic interactions generated in a reversible way. Photoin-duced heterolysis of rotaxanes with diaryl-methoxy-cycloheptatriene- and aryl-alk-oxy-acridane-based molecular threads was used in the group of Abraham to demonstrate this concept. Abraham, Grubert, Grummt, and Buck [93] synthesized a rotaxane composed of the tetracationic macrocycle cyclobis(paraquat-p-phenylene) CBPQT (Fig. 9bl) and a thread that incorporated a diaryl-methoxy-cycloheptatriene unit (Fig. 9b2) the thread was folded. In the initial situation (Fig. 9b6), the macrocycle is located at the diary 1-methoxy-cycloheptatriene station (station 1), but due to folding, it interacts also with the aromatic station 2 (for the sake of convenience, the thread in... 

Stoddart et al. developed the donor-acceptor n-n interaction template synthetic strategy. The main interaction holding the components together in a certain supramolec-ular system is the aromatic stacking forces. The most frequently used donor units are 1,5-dioxynaphthalene (DNP), tetrathiafulvalene (TTF), dihydroxyl xenene ether-ate, diamino xenene etherate, and so on. The acceptor units in common use are cyclobis(paraquat-/ -phenylene) (CBPQT" +), viologen, and so on. As shown in Figure 10, ... 

In 1997, a [2]catenane bearing Cgo was synthesized through Stoddart s methodology,exploiting n-n interactions between aromatic moieties. " The double Bingel addition of a [34]crown-10 bismalonate to Cgo was followed by a ring-closed reaction, where the electron-deficient cyclobis-(paraquat-p-phenylene) (CBPQT +) macrocycle recognizes the electron-rich hydroquinone template. 

The controlled movement in this system is controlled by the interaction among redox-active units at the redox-active tetrathiafulvalene (TTF) units. In the neutral, unperturbed state, the tetracationic cyclophane units (cyclobis(paraquat-para-phenylene), CBPQ F ) are most stable coordinated to the TTF moieties, due to electron donation and Jt-stacking interactions. However, upon oxidation of the TTF units, the CBPQT " rings become electrostatically repelled, migrating to the... 

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