Related Experiment Video
Updated: Aug 22, 2025

Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
Published on: June 10, 2021
Janus-Type AIE Fluorophores: Synthesis and Properties of π-Extended Coumarin-Bearing Triskelions
Masafumi Ueda1, Mirai Kokubun1, Nao Yanagi2
1Department of Chemistry, Graduate School of Science, Kitasato University, Kanagawa 252-0373, Japan.
Abstract:
Janus-type triskelion-shaped fluorophores comprising coumarins bearing various electron-donating substituents (1aad, 1add, 1ccd, and 1cdd) were successfully synthesized via an intramolecular Ullmann coupling. Density functional theory (DFT) calculations indicated that all the compounds presented two different molecular surfaces, similar to Janus-type molecules. The absorption and fluorescence spectra of asymmetrical derivatives 1aad, 1add, 1ccd, and 1cdd exhibited a bathochromic shift due to their narrow highest occupied molecular orbital (HOMO) -lowest unoccupied molecular orbital (LUMO) gap. Natural transition orbital (NTO) analysis indicated that the excited state orbital overlaps differ among the C3 symmetrical and asymmetrical dyes. These triskelion-shaped fluorophores were found to form molecular nanoaggregates in THF/H2O mixtures and demonstrated aggregation-induced emission (AIE) enhancement characteristics as a result of restricting their molecular inversion. These results indicate that Janus-type AIE fluorophores are potentially applicable as solid-state fluorescent chiral materials, which can be optimized by controlling their molecular rearrangement in the solid state.
More Related Videos
Related Concept Videos
Aromatic Hydrocarbon Cations: Structural Overview
Removing one hydrogen from the intervening CH2 group...
Aromatic Hydrocarbon Anions: Structural Overview
Due to the absence of continuous...
UV–Vis Spectroscopy: Woodward–Fieser Rules
Aryldiazonium Salts to Azo Dyes: Diazo Coupling
Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
Frost Circles for Different Conjugated Systems

