Related Experiment Video
Updated: Apr 28, 2026

Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles
Published on: August 22, 2018
Cyclic azacyanines: experimental and computational studies on spectroscopic properties and unique reactivity
Digambara Patra1, Teresa A Palazzo, Nagham N Malaeb
1Department of Chemistry, American University of Beirut, Beirut, Lebanon, dp03@aub.edu.lb.
Abstract:
The absorption and fluorescence properties of cyclic azacyanine (CAC) derivatives were examined in several solvents. The presence of electron donating or withdrawing groups on the CAC impacts spectroscopic properties. The general solvent relaxation displayed by azacyanine derivatives is in accordance with Lippert-Mataga's prediction but exception is noted in the case of protic solvent due to specific hydrogen bonding interactions. Fluorescence lifetime decay studies indicate a relaxation time in the nanosecond timescale with mono exponential decay. Donating substituents markedly increase the excited state lifetime, whereas withdrawing groups marginally decrease the excited state lifetime. Quantum chemical computations were used to explore the origins of the reactivity and spectroscopic properties of CACs; results are consistent with a model in which regioselectivity results from differences in mechanistic steps occurring after initial attack by hydroxide on the CAC.
Related Concept Videos
Aryldiazonium Salts to Azo Dyes: Diazo Coupling
Aromatic Hydrocarbon Cations: Structural Overview
Removing one hydrogen from the intervening CH2 group...
Nucleophilic Aromatic Substitution of Aryldiazonium Salts: Aromatic SN1
In the Sandmeyer reaction, for example, the diazonio group is replaced by a chloro, bromo,...
Cycloaddition Reactions: MO Requirements for Photochemical Activation
Aromatic Hydrocarbon Anions: Structural Overview
Due to the absence of continuous...
Diazonium Group Substitution with Halogens and Cyanide: Sandmeyer and Schiemann Reactions

