Supramolecular assembly arene polymers

Wang and co-workers used the mono-bromide 3.58 as a key compound to construct a pillar[5]arene-based supramolecular assembly. The monobromide 3.58 was substituted with an amino group by Gabriel synthesis. A mono-ureidopyrimidinone-functionalized pillar[5]arene (3.65) was synthesized from the mono-amine 3.64. 3.65 formed a supramolecular dimer by a quadruple hydrogen bond between ureidopyrimidinone moieties, and addition of a bisparaquat derivative afforded supramolecular polymers at high concentration. 

Recently, Zhao and co-workers constructed a supramolecular polymer network by mixing the pillar[5]arene trimer 7.35 with a bisparaquat linker (7.36). In particular, as the concentration of the mixture increased, the supramolecular assemblies obtained transformed from vesicular structures, to tubular objects, layers and staeked layers (Figure 7.20). 

Another example of supramolecular columnar polymers formed by the combined use of hydrogen bonding and arene—arene interactions are the complexes of tetrazoles and l,3,5-tris(4,5-dihydroimidazol-2-yl)-benzene (53, Figure 28).231 Four molecules self-assemble to give a supramolecular disc-shaped molecule, which subsequently polymerizes into columns when in nonpolar solvents. Upon formation of a... 

R. Sun, X. Ma, M. Gao, H. Tian, Q. Li, Light-driven linear helical supramolecular polymer formed by molecular-recognition-directed self-assembly of bis-p-sulfonatocalix[4]arene and pseudorotaxane. J. Am. Chem. Soc. 135, 5990-5993 (2013)... 

By using the click reaction, Stoddart and co-workers connected a viologen unit to the pillar[5]arene moiety to obtain a mono-functionalized pillar[5]arene (7.13 Scheme 7.1). As the concentration increased in the range of 0.1-100 mM in dichloromethane, the assemblies of 7.13 changed from self-inclusion complexes to linear supramolecular polymers. In addition, gels could be formed after a sealed solution of 7.13 at concentrations above 25 mM in dichloromethane had been left to stand for 12 h. 

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... 

The chemistry of supramolecular polymers has been extensively reviewed [5], In the past two decades, general overviews as well as more specific surveys have focused on individual classes of polymers or on the mechanisms and thermodynamics of supramolecular polymerization. The present chapter aims to retrace the genesis and the evolutiOTi of that subgroup of supramolecular polymers that share the calix[5]arene skeletmi as their common building block. To this end, relevant examples of dimeric capsules and/or encapsulation complexes key to the subsequent design of polycapsular AA/BB-type arrays, as well as discoveries pivotal to an effective self-assembly of AB-type architectures are surveyed in parallel. 

This section deals with a third recognition motif that has mainly been used to assemble calix[4]arene-based supramolecular polymers, but has also generated a couple of examples of calix[5]arene-based polymers. The molecular recognition between p-sulfonatocalix[ ]arenes ( = 4—8) and positively charged species (organic or inorganic) in aqueous medium heavily relies on Coulombic interactions... 

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