Poly cyclic arenes

A novel transformation was observed when calix[n]arene ( = 4 or 6) was oxidized to generate the cyclic poly-1,4-diketone 11, which when subjected to Paal-Knorr conditions gave (12, n = 3) whereas, it was treated with hydrazine gave the isopyrazole-based macrocycles 13 <04T1895>. 

A main chain polyrotaxane, a mechanically interlocked structure that can be considered as a string of pearls, in which the strand is the polymer backbone and the pearls are the cychc species threaded onto the strand. The backbone polymer can be a polyester, polyamide, poly(ethylene oxide), or virtually any linear polymer. The cyclic species are typically crown ethers, cyclodextrins (CDs), cucurbimrils, and calix-arenes. Polyrotaxanes can be made by two different methods statistical threading or via the template approach (enthalpi-cally driven). The statistical approach utilizes le Chatelier s principle with an excess macrocycle during the polymerization. The template approach is driven by attractive interactions of the macrocyclic species with either the monomer... 

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