Related Experiment Video
Updated: Jun 20, 2026

Qualitative Identification of Carboxylic Acids, Boronic Acids, and Amines Using Cruciform Fluorophores
Published on: August 19, 2013
Cucurbit[7]uril complexation drives thermal trans-cis-azobenzene isomerization and enables colorimetric amine
1Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20705, USA.
Abstract:
Complexation of yellow diaminoazobenzenes 1 and 3 inside cucurbit[7]uril (CB[7]) results in the formation of purple-colored CB[7].cis-1.2H+ and CB[7].cis-3.2H+ complexes, respectively. The high binding affinity and selectivity displayed by CB[7] toward 1 and 3 pays the >10 kcal mol(-1) thermodynamic cost for this isomerization. We investigated the behavior of these complexes as a function of pH and observed large pK(a) shifts and high pH responsiveness, which are characteristic of cucurbit[n]uril molecular containers. The remarkable yellow to purple color change was utilized in the construction of an indicator displacement assay for biologically active amines 4-10. This indicator displacement assay is capable of quantifying the pseudoephedrine (5) content in Sudafed tablets over the 5-350 microM range.
More Related Videos
10:02Quantitative SERS Detection of Uric Acid via Formation of Precise Plasmonic Nanojunctions within Aggregates of Gold Nanoparticles and Cucurbit[n]uril
Published on: October 3, 2020
03:38Aptamer-Based Target Detection Facilitated by a 3-Stage G-Quadruplex Isothermal Exponential Amplification Reaction
Published on: October 6, 2022
Related Concept Videos
Aryldiazonium Salts to Azo Dyes: Diazo Coupling
Physical Properties of Amines
Basicity of Heterocyclic Aromatic Amines
Preparation of 1° Amines: Hofmann and Curtius Rearrangement Overview
Amines to Sulfonamides: The Hinsberg Test
Generally, a primary amine reacts with the Hinsberg reagent to produce an N-substituted benzenesulfonamide. The electron-withdrawing sulfonyl...
Preparation of 1° Amines: Azide Synthesis
Azide ions act as good nucleophiles and react with unhindered alkyl halides to form alkyl azides. Alkyl azides do not participate in further nucleophilic substitution reactions, thereby eliminating the chances of polyalkylated products. Alkyl azides are reduced by hydride-based reducing agents, like lithium aluminum...