Supramolecular Daisy Chains

Abstract

Our childhoods may be recalled when a self-complementary cation, endowed with both a dibenzo[24]crown-8 macroring and a secondary dialkylammonium sidearm, self-assembles to form a two-component supramolecular architecture that is reminiscent of a daisy chain (depicted schematically on the right). This daisy-chain-like superarchitecture is stabilized by a combination of [N -H⋅⋅⋅O] hydrogen bonds and aryl-aryl stacking interactions.

Synthesis and Characterization of Poly[3]rotaxane through the Mizoroki-Heck Coupling Polymerization of Divinyl-functionalized [3]Rotaxane

“…Among polyrotaxanes as one of the interlocked polymers (Figure 1), both poly [2]rotaxane [21][22][23][24][25][26][27][28][29][30][31][32][33] and poly [3]rotaxane 34,35 are specially unique as characterized by their structural feature that the polymer main chain has no successive covalent bond. The repeating units of these polymers are bound by mechanical bonds.…”

“…34 Further, we have recently disclosed the synthesis of poly [2]rotaxane by the polymerization of a bifunctional rotaxane monomer via the Sonogashira coupling reaction, 47 while a few poly [2]rotaxanes were synthesized by the thermaldynamic process. 21,22,[24][25][26][27][28] There are two possible ways accessing the main chain-type poly [3]rotaxane: one goes through the initial rotaxanation followed by the polymerization (Figure 2, route A), whereas the other undergoes the initial coupling of wheel followed by the rotaxanation to poly [3]rotaxane ( Figure 2, route B), as shown in Figure 1. Our previous paper 33 described the synthesis of a polyrotaxane by rotaxanation of ditopic wheel component utilizing the dynamic covalent chemistry of disulfide linkage, along Route B.…”

Crown Ether‐Based Polymeric Rotaxanes

“…In both cases the length of the array is dependent upon the association constant of the host-guest system and the concentration; to form long oligomers or polymers, it is crucial that the host-guest pairs have extremely high association constants [2]. In addition to their dependence upon association constants, daisy chain formation can be hindered by the tendency to form cyclic dimers as side products [3,[6][7][8][9].…”

“…Stoddart and coworkers reported that the trifluoroacetate salt of 2 led to the formation of the cyclic dimer, via self-complexation [7,8]. An X-ray crystal structure of the cyclic dimer was provided, and MS results revealed only the dimer [7,8]. However, Gibson et al reported 2 (as the PF 6 salt) and showed that oligomers could be formed from this compound [9].…”

Identification of face-to-face inclusion complex formation of cyclodextrin bearing an azobenzene group by electrospray ionization mass spectrometry

“…When a guest group is modified with a cyclic host, the molecule may form intramolecular complexes [2] or intermolecular complexes [3] to give supramolecular polymers. When supramolecular polymers are treated with bulky stopper groups, they may form poly [2]rotaxanes [4].…”