A versatile template for the formation of [2]pseudorotaxanes. 1,2-Bis(pyridinium)ethane axles and 24-crown-8 ether wheels

Abstract

Linear 1,2-bis(pyridinium)ethane 'axles' and macrocyclic 24-membered crown ether 'wheels' (, and ) combine to form [2]pseudorotaxanes. These interpenetrated adducts are held together by N+...O ion-dipole interactions, a series of C-H...O hydrogen bonds and pi-stacking between electron-poor pyridinium rings of the axle and electron-rich catechol rings of the wheel. 1H NMR spectroscopy was used to identify the structural details of the interaction and to determine the thermodynamics of the binding process in solution. Analysis of nine of these adducts by single crystal X-ray crystallography allowed a detailed study of the non-covalent interactions in the solid state. A wide variety of structural changes could be made to the system. The versatility and potential of the template for the construction of permanently interlocked structures such as rotaxanes and catenanes is discussed.

One‐, Two‐ and Three‐Periodic Metal–Organic Rotaxane Frameworks (MORFs): Linking Cationic Transition‐Metal Nodes with an Anionic Rotaxane Ligand

“…As expected, there was a substantial increase in association constant upon benzylation; from 8.0 10 1 to 2.3 10 3 m À1 comparing DB24C8 to DSDB24C8 2À . These values compare well to those observed for similar systems [14] and verify that [2&DSDB24C8] À should be capable of acting as a pseudorotaxane linker between metal ions in a MORF.…”

Rotaxanes as ligands: from molecules to materials

“…2. 4 The strength of the non-covalent interactions could be controlled by varying the substituents on the axle pyridinium rings. In particular, an EWG provides increased hydrogen bonding and electrostatic interactions and therefore an increase in the stability of the system.…”

A New Glycorotaxane Molecular Machine Based on an Anilinium and a Triazolium Station

“…Although recent papers described on one hand the use of the "click chemistry" as an efficient route to triazolrotaxanes [7] and on another hand the recognition study of anions by 1,2,3-triazolium receptors, [8] the N-methyltriazolium moiety has never been described as a molecular station for DB24C8 so far. However, since Busch et al reported the ability for the DB24C8 to interact strongly with ammonium cation, [9] a wide variety of other template moieties, such as benzylic ammonium, [10] N-benzylic anilinium, [11] N,N'-di-A C H T U N G T R E N N U N G alkyl-4,4'-bipyridinium, [12] 1,2-bis(pyridinium)ethane cations, [13] The already reported N-alkylanilinium was chosen as the templated moiety for the preparation of the [2]rotaxane 3, and, at the same time, as the best molecular station for DB24C8 in the targeted molecular machine 4. The cationic electron-poor aromatic ring N-methyltriazolium should be able to interact with the DB24C8 either by p-p stacking with the electron-rich catechol ring, by ion-dipole interactions between the cationic charge and the oxygens of the macrocycle or by hydrogen bond between the vinylic hydrogen of the triazolium and the oxygens of the macrocycle.…”