Cyclophane Hosts

Forman, J. E., Barrans, R. E., Dougherty, D. A., Circular-dichroism studies of molecular recognition with cyclophane hosts in aqueous-media. J. Am. Chem. Soc. 1995, 117, 9213-9228. 

Diederich, F., Complexation of neutral molecules by cyclophane hosts. Angew. Chem., Int. Ed. Engl. 1988, 27, 362-386. 

Weber, E., Helbig, C., Seichter, W., Czugler, M., A new functional cyclophane host. Synthesis, complex formation and crystal structures of three inclusion compounds. J. Incl. Phenom. Macrocycl. Chem. 2002, 43, 239-246. 

It was converted to the phthalimide via a Mitsunobu reaction, reduced to the amine, and the amine was coupled with />-nitrophenylacetic acid to give the precursor to the macrocycle. Macrocylization was done via Troger s base formation using Johnson s method, which resulted in two isomers of the amide macrocycle. These were separated and reduced to give the cyclophane host. This was the first time two diastereomers were observed in these syntheses and the separation of these diastereomers was very difficult. 

Similar results have been reported for the host/guest complex formation between a tetracationic cyclophane host [=cyclobis(paraquat-p-phenylene)j and the planar het-eroarene indole. The binding constants Kg, determined in six solvents of different polarities, increase with increasing solvent polarity, being ca. 100-fold greater in water than in acetone [306]. Further examples of solvent-dependent cyclophane/guest complexation reactions can be found in reference [299],... 

F. Diederich, Complexation of Neutral Molecules by Cyclophane Hosts , Angew. Chem. Int Ed., 27,362 (1988)... 

Calixarenes have also been used as cyclophane hosts for the binding of quinone acceptors via hydrogen bonding. Arimura and Sessler have appended bis-hydroxy-containing calix[4]arenes to zinc(II) porphyrins. Two phenolic OH groups on the calix[4]arene serve as tweezers to complex a quinone via two-point hydrogen... 

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