New Synthetic Host Pillararenes: Their Synthesis and Application to Supramolecular Materials

Abstract

In 2008, we reported a new class of macrocyclic hosts called "pillararenes." They combine the advantages and aspects of traditional hosts and have a composition similar to those of typical calixarenes. Pillararenes have repeating units connected by methylene bridges at the para-position of benzene moieties, and thus they have a unique symmetric pillar architecture differing from the basket-shaped structure of calixarenes bridged at the meta-position of benzene moieties. Pillararenes show high functionality similar to cyclodextrins and can capture electron-accepting guest molecules within their cavity similarly to cucurbiturils. In this account, the synthesis, structure, and hostguest properties are discussed, along with pillararene-based supramolecular architectures.

Pillar[5]arenes with Morpholide and Pyrrolidide Substituents: Synthesis and Complex Formation with Alkali Metal Ions

“…For the synthesis of new pillar [5]arene derivatives, two synthetic ways are possible: functionalization of pre-formed perhydroxylated pillar [5] arene 2 (Scheme 1) and cyclization/co-cyclization of 1,4-dialkoxybenzene monomers. [16] In this work, we used first way which consists of step-by-step functionalization of the initial perhydroxylated pillar [5]arene 2. This approach was successfully applied to the synthesis of the thiacalix [4]arene derivatives and made it possible to obtain functionalized macrocycles with high yields.…”

Radical-radical rotaxanes with tetracationic cyclophane ring, and quaternary azaaromatic rotaxanes with cage macrocycles

“…In this process an "unlikely rotaxane" R·6PF 6 consisting of two positively charged components, i.e. the thread and the ring was synthesized.…”

“…The synthesis of [2]rotaxane R•6PF 6 by treatment with di-t-butyl acetylenedicarboxylate for introduction of stoppers via click reaction, affords the rotaxane R…”

“…Therefore this process is accompanied by the shuttle of W 4+ away from the BIPY 2+ unit resulting in the formation of the "unlikely rotaxane" R•6PF 6 .…”

“…The second part deals with rotaxanes consisting of quaternary azaaromatic thread and cage macrocycles serving as rings; for cage macrocycles cyclodextrins, 4 calixarenes, 5 pillararenes 6 and cucurbiturils 7 have been chosen. As examples, the rotaxanes containing one or more rings of the same kind, as well as rotaxanes containing different rings are presented, pointing out their application possibilities on various fields.…”