Self‐assembling [2]‐ and [3]Rotaxanes from Secondary Dialkylammonium Salts and Crown Ethers

Abstract

The self-assembly of three new rotaxanes-two[2]rotaxanes and a [3]rotaxane-formed by a "threading followed by stoppering" approach is described. These template-directed syntheses rely on the formation of pseudorotaxane intennediates, which self-assemble in solution from functionalized secondary dialkylammonium hewafluorophosphate threads and macrocyclic polyether rings (either dibenzo-[24]crown-8 or its asymmetric constitutional isomer). The stoppers-substituted 1,2,3-triazoles-were created by thermally allowed 1,3-dipolar cycloadditions between azido groups, which terminate the threads, and di-tert-butyl acetylenedicarboxylate. lar

A New Motif for the Self-Assembly of [2]Pseudorotaxanes; 1,2-Bis(pyridinium)ethane Axles and [24]Crown-8 Ether Wheels

“…[1] The composition TeN was ascribed to this yellow, extremely poorly soluble, and highly exlosive substance. Considering the analogy to the crystallographically well characterized homologues S 4 N 4 [2] and Se 4 N 4 , [3] this assignment has not been entirely ruled out to this day. [4] However, later analytical work made the composition Te 3 N 4 with tetravalent tellurium probable.…”

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The threading of the paraquat dication PQT 2 through the cavity of bis(paraphenylene) [34]crown-10 (BPP34C10) to form the [2]pseudorotaxane [(BPP34C10)(PQT)] 2 (1) was the genesis of a diverse range of molecules that contain mechanical linkages (rotaxanes, catenanes, molecular shuttles, and switches) derived from this basic interaction, and stands as a landmark discovery in the area of supramolecular chemistry (Scheme 1).[ now been reported involving p stacking between electron-rich and electron-poor aromatic rings, [2] hydrogen bonding between secondary dialkylammonium ions and crown ethers [3] or between amides and large ring lactams, [4] hydrophobic interactions within the cavity of a cyclodextrin, [5,6] and metal ± ligand interactions between transition metal ions and cyclic ligands.[7±9] In many of these systems the ion ± dipole interaction between positively charged atoms of one component and the Lewis basic atoms of the other component makes a significant contribution to the binding. Although these electrostatic interactions are not directional and predictable in the same manner as hydrogen bonds or metal ± ligand bonds, they are nonetheless extremely important.

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Combining Different Hydrogen-Bonding Motifs To Self-Assemble Interwoven Superstructures

“…Bis(4-carboxybenzyl)ammonium hexafluorophosphate (4´PF 6 ): Bis(4-carbomethoxybenzyl)amine (15, [36] 0.52 g, 1.7 mmol) was transformed into the title compound by the general procedure given above for 2´PF 6 . It was acquired as a white solid (0.46 g, 65 %).…”

Polyrotaxane and Polyrotaxane Network: Supramolecular Architectures Based on the Concept of Dynamic Covalent Bond Chemistry

“…The first preparation of oligorotaxane consisting of crown ether and ammonium salt was carried out by Stoddart et al via the 1,3-dipolar cycloaddition of azide to di-tert-butyl acetylenedicarboxylate. 15,16 Although the 1,3-dipolar cycloaddition took place under neutral condition, the yield of the rotaxane was rather low because the higher reaction temperature which suppressed the pseudorotaxane formation was necessary.…”