Related Experiment Video
Updated: Aug 24, 2026

Self-assembling Morphologies Obtained from Helical Polycarbodiimide Copolymers and Their Triazole Derivatives
Published on: February 7, 2017
Cooperative molecular recognition of dyes by dyad and triad cyclodextrin-crown ether conjugates
Yu Liu1, Ying-Wei Yang, Lei Li
1Department of Chemistry, State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, PR China. yuliu@public.tpt.tj.cn
Abstract:
Three beta-cyclodextrin (beta-CyD) derivatives with crown ether units, that is N-(4'-benzo-15-crown-5)-6-imino-6-deoxy-beta-CyD (2), 6,6'-[N-(4,4'-dibenzo-18-crown-6)-imino]-bridged bis(beta-CyD)(3), and 2,2'-[O-(4',5'-benzo-15-crown-5)-ethyl]-bridged bis (beta-CyD)(5), were synthesized as cooperative recognition receptor models. Their molecular binding behavior with four representative fluorescent dyes, i.e., ammonium 8-anilino-1-naphthalenesulfonate (ANS), sodium-6-toluidino-2-naphthalene-sulfonate (TNS), Acridine Red (AR) and Rhodamine B (RhB), was investigated in buffer solutions (pH = 7.20) at 25 degreesC by means of circular dichroism, NMR and fluorescence spectroscopy. 2D-ROESY experiments showed that dyad host 2 and triad host 3 adopted a CyD-guest-crown ether binding mode, while triad host 5 adopted a CyD-guest-CyD binding mode, upon inclusion complexation with guest molecules. Therefore, hosts 2 and 3 showed high molecular recognition ability towards charged guests, giving an enhanced binding ability up to 115 times for ANS by 3 and fairly high molecular selectivity up to 1450 times for the ANS/AR pair by 2 as compared with native beta-CyD in an aqueous phosphate buffer solution. On the other hand, host 5 was found to be able to effectively recognize the shape of a guest molecule, showing significantly higher binding ability towards linear guests. The binding affinities and molecular recognition abilities of these CyD-crown ether conjugates towards guest molecules are discussed from the viewpoint of electrostatic and/or hydrophobic interactions, size/shape-fit concept, and multiple recognition mechanism between host and guest.
More Related Videos
09:28Engineering Molecular Recognition with Bio-mimetic Polymers on Single Walled Carbon Nanotubes
Published on: January 10, 2017
12:51A 'Plug and Play' Method to Create Water-dispersible Nanoassemblies Containing an Amphiphilic Polymer, Organic Dyes and Upconverting Nanoparticles
Published on: November 14, 2015
Related Concept Videos
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
Crown Ethers
Photochemical Electrocyclic Reactions: Stereochemistry
Selection Rules: Photochemical Activation
Thermal Electrocyclic Reactions: Stereochemistry
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Cycloaddition Reactions: MO Requirements for Thermal Activation
Thermal and Photochemical Electrocyclic Reactions: Overview