Catenated Cyclodextrins

Abstract

Abstract:A novel synthetic approach is described for the construction of catenanes in aqueous solution from a partially methylated cyclodextrin (CD)-namely. hepta kis(2,6-di-O-methyl-~-cyclodextrin)

Donor–Acceptor Oligorotaxanes Made to Order

“…The [2]rotaxane [2]1NPR·4 PF 6 was obtained (Scheme 4) by converting 2 (1NP) [21] to the ditosylate [22] 3, which was then treated with NaN 3 in DMF to afford the diazide [22] 4, before subjecting it to copper-catalyzed azide-alkyne cycloaddition [23] (CuAAC) in the presence of CBPQT·4 PF 6 and the propargyl derivative [14] 5, the precursor to the stoppers. This template-directed protocol involves the mixing of the diazide 4 with the CBPQT·4 PF 6 and the alkyne 5 at room temperature in Me 2 CO in the presence of the copper catalyst.…”

Synthesis of A Bis‐Macrotricyclic Host and Its Complexation with Secondary Ammonium Salts: An Acid–Base Switchable Molecular Handcuff

“…Synthesis of guest 4 is outlined in Scheme 2. Ditosylation of diol 8 [12] and then reaction with 4-hydroxybenzaldehyde gave 10. Condensation of 10 with benzylamine, reduction with NaBH 4 , protonation of the resulting amine, and counterion exchange with NH 4 PF 6 formed target guest 4 in 88 % yield over the four steps.…”

Threading Cyclodextrins in Chloroform: A [2]Pseudorotaxane

“…In order to gather preliminary evidence on the possibility of building a supramolecular switching system, the binding constants for the complexes of cyclodextrin 1 and two different guest molecules – chosen as prototype stations– were determined by 1 H NMR dilution experiments [15,43], both in aqueous and in organic media. The binding experiments were carried out by progressively diluting equimolar solutions of 1 with each of the two guests, namely the biphenyl derivative 3 [15] ( vide infra , Scheme 1) and N , N ′-dibenzyl-4,4′-bipyridinium ( 8 2+ ), gave the expected results (Table 1), proving that CD 1 displays a good affinity for both the dicationic guest 8 2+ and the neutral aromatic guest 3 in acetone and in water-rich media, respectively.…”

“…The binding experiments were carried out by progressively diluting equimolar solutions of 1 with each of the two guests, namely the biphenyl derivative 3 [15] ( vide infra , Scheme 1) and N , N ′-dibenzyl-4,4′-bipyridinium ( 8 2+ ), gave the expected results (Table 1), proving that CD 1 displays a good affinity for both the dicationic guest 8 2+ and the neutral aromatic guest 3 in acetone and in water-rich media, respectively.…”

“…CDs and their chemically modified derivatives have been used over the years as building blocks for the construction of the most diverse supramolecular architectures. Interlocked supermolecules [10–12], such as rotaxanes [13,14] and catenanes [15], supramolecular polymers [16], and artificial enzymes [17,18], have all been self-assembled or synthesized using CDs as the macrocyclic component, harnessing their innate tendency to form, with suitable guests, inclusion compounds with a pseudorotaxane-like geometry. Cyclodextrin-based rotaxanes and pseudorotaxanes have also been employed for the construction of molecular switches [11,19,20], activated by electrochemical [21], photochemical [22–24], thermal [22] or chemical stimuli [25].…”