Supramolecular Polymers based on Pillararenes

MENGFEI NI, XIAO-YU HU, JULI JIANG AND LEYONG WANG  

Key Laboratory of Mesoscopic Chemistry of MOE, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China Email lywang nju.edu.cn 

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One advantage of the supramolecular polymers constructed by orthogonal assembly is their enhanced responsiveness to multiple external stimuli. Recently, a thermo- and photo-responsive supramolecular polymer based on pillar[5]arene was reported by Yang s group, ° where the anthracene group was used as the photo-responsive unit, and the pillar[5]arene/imidazole binding motif was employed as the thermo-responsive unit. When an anthracene-modified pillararene (7.27) was irradiated with UV light [1 >360 nm), the anthracene unit dimerized and the pillar[5]arene dimer... 

In this chapter, we have tried our best to summarize different examples of the pillararene-based supramolecular polymers shown in the published journals so far. It is worth mentioning that many of these examples have been beyond the simple construction of supramolecular polymers. These outstanding researches are focusing on stimuli-responsive polymers, supramolecular gels, molecular devices, and the modification of polymeric materials. However, more functions and applications of pillararene-based supramolecular polymers need to be explored in the future. On the other hand, most supramolecular polymers discussed in this chapter are based on pillar[5]arenes, which is attributed to the facile synthesis of pillar[5]arenes when compared with other pillar[n]arenes. Therefore, the research on supramolecular polymers based on other pillar[n]arenes, especially pil-lar[6]arenes, will also be a challenge. 

Macrocycles play an important role in the development of supramolecular chemistry. Based on the traditional macrocycles such as crown ethers, calixarenes, cyclodextrins, and cucurbiturils, a great many supramolecular polymers as well as their applications have been reported. Because pillar-arenes have only had 6 years of development (from 2008), the research on pillararene-based supramolecular polymers is at a preliminary stage. However, all of the efforts made and aehievements that have been reached suggest that pillararenes as well as pillararene-based supramoleeular polymers will have a bright future. 

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