Related Experiment Video
Updated: Aug 28, 2026

Preparation of a Corannulene-functionalized Hexahelicene by Copper(I)-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units
Published on: September 18, 2016
Tuning Halide Induced Metastability in a [2]Rotaxane by Varying Axle, Crown Ether, and Employing Bistability
Nidhi Pandey1, Suvankar Dasgupta1
1Department of Chemical Science and Technology, NIT Patna, Patna, India.
Abstract:
4-isopropylphenyl slippage stopper has been used for developing a series of [23]crown ether incorporated metastable [2]rotaxanes via click reaction. Two [23]crown ethers that is, 23C7 and X23C7 are employed. The crown ether stationed at the ammonium site exhibited extrusion selectively in the presence of fluoride anion (TBAF) over TBAX (X = chloride, bromide, and iodide) due to TBAX exhibiting H-bonding with the neutral triazole moiety of the axle. Replacing 23C7 by X23C7 has enhanced the overall stability of the [2]rotaxane by reducing the impact of metastability. Imparting bistability to the metastable [2]rotaxanes by transforming triazole to methyl triazolium (MTA+) moiety, offers the crown ether to choose between shuttling and extrusion, touting this as a competition between the two phenomena switching and metastability. Surprisingly, TBAF addition reveals preferential extrusion in case of 23C7 incorporated bistable [2]rotaxane while preferential shuttling was observed with X23C7 incorporated bistable [2]rotaxane. Micromolar to millimolar concentration variation has a telling effect on the mode of responsiveness in a bistable [2]rotaxane with a slippage stopper. On the contrary, in polar medium (DMSO-d6), extrusion is the only mode of responsiveness observed by NMR spectroscopy.
More Related Videos
Related Concept Videos
Stability of Substituted Cyclohexanes
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
Halogenation of Alkenes
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
Chair Conformation of Cyclohexane
The hydrogen atoms linked to carbons are arranged in two different axial and equatorial orientations to achieve this staggered...
Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...
Stereoisomerism of Cyclic Compounds
Conformations of Cyclohexane
The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal tetrahedral value,...

![Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-(phosphinetriyl)tripiperidine]}palladium Under Mild Reaction Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F51444.jpg&w=3840&q=50)