Binding of secondary dialkylammonium salts by pyrido-21-crown-7

Templated versus non-templated synthesis of benzo-21-crown-7 and the influence of substituents on its complexing properties

“…Among these, the threaded interaction of secondary ammonium ions with larger crown ethers is a prominent example [17–22]. Recently, Huang and co-workers reported that the macrocycle size for forming pseudorotaxane can be reduced to only 21 atoms, namely benzo-21-crown-7 [23] ( C7 ; Scheme 1) and pyrido-21-crown-7 [24], which could still slip over a secondary dialkylammonium ion when one of the alkyl groups is a narrow alkyl chain. By using this binding motif, the so far smallest [2]rotaxane consisting of only 76 atoms and having a molecular weight of not more than 510 Da was synthesized by Chiu and co-workers [25].…”

Fibrous Networks with Incorporated Macrocycles: A Chiral Stimuli‐Responsive Supramolecular Supergelator and Its Application to Biocatalysis in Organic Media

“…The cavity size of the crown is not only suitable for K + binding, but also allows dialkylammonium ions to form pseudorotaxanes by threading through the crown ether. [15] As a third chemical stimulus, competitive anions such as chloride can interfere with the urea-urea hydrogen bonding between adjacent gelator molecules. [16] The gelator enantiomers (R)-1 and (S)-1 were synthesized as summarized in Scheme 1.…”

Synthesis, structure and properties of the macrocyclic ferrocenophanes with cyclopentadienyl ligands tethered by oligo(ethylene glycol) chain

“…The difference in the 1 H NMR signals between the complexed and uncomplexed macrocycle is ascribed to the restricted ring motion in ferrocene unit in pseudorotaxane [(6){NH 2 ((CH 2 ) 9 Me) 2 }]BARF. The association constant K a (5.1 Â 10 3 M À1 at 25 C) is obtained from the 1 H NMR and found to be larger than that of the complex of P21C7 (pyrido[21]crown-7) and [NH 2 (nBu) 2 ]PF 6 in acetone-d 6 (K a ¼ 1625 M À1 at 22 C) [13]. Stoddart et al investigated complexation of DB24C8 and di(n-alkyl) ammonium with PF 6 À anion in CDCl 3 and concluded that low solubility of the dialkylammonium in the less polar solvent prevented determination of precise association constant [15].…”

“…The macrocyclic structures of these 1,1 0 -ferrocenylene-containing crown ethers were considered to influence the formation of the hosteguest complexes with the cationic ions or molecules. Akabori reported detailed structure of the complex of a pentaoxa [13]ferrocenophane and NaSCN [6e]. In this paper we report preparation of macrocyclic 1,1 0 -ferrocenophanes as well as their structures in the solid state, electrochemical properties, and pseudorotaxane formation in solution.…”