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Photogeneration of N-Heterocyclic Carbenes: Application in Photoinduced Ring-Opening Metathesis Polymerization
Published on: November 29, 2018
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Visible-Light Switchable Rings and Chains in Dynamic Covalent Imine Chemistry
Jona Voss1,2, Yannic Hartmann1, Esther Nieland1
1Institut für Organische Chemie und Makromolekulare Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, Düsseldorf, Germany.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|March 27, 2025
Summary
Red-light switchable azobenzene isomers form distinct macrocycles with diamines. Chain length dictates self-assembly, enabling control over photoresponsive materials via dynamic covalent chemistry.
Area of Science:
- Supramolecular Chemistry
- Organic Chemistry
- Materials Science
Background:
- Azobenzene derivatives are photoresponsive molecules with tunable properties.
- Self-assembly of functionalized molecules offers pathways to complex structures.
- Dynamic covalent chemistry utilizes reversible reactions for adaptive materials.
Purpose of the Study:
- To investigate the self-assembly of red-light switchable ortho-difluoroazobenzene isomers with aliphatic diamines.
- To understand the influence of diamine chain length on macrocycle formation and photoresponsiveness.
- To explore the potential of these systems in dynamic covalent chemistry and adaptive materials.
Main Methods:
- Synthesis of functionalized ortho-difluoroazobenzene isomers (E-/Z-A).
- Reaction with various aliphatic diamines (e.g., propane-1,3-diamine, butane-1,4-diamine).
- Characterization using single-crystal X-ray diffraction, 19F-DOSY NMR, MALDI-MS, and UV/Vis spectroscopy.
Main Results:
- Self-assembly exhibits alternating behavior based on diamine chain length (odd vs. even).
- Even-numbered diamines exclusively form imine macrocycles with the Z-azobenzene isomer.
- Odd-numbered diamines form photoswitchable, defined macrocycles, including E,E-A2X2 types, confirmed by X-ray structures.
Conclusions:
- Diamine conformation, influenced by methylene group count, dictates reactivity and self-assembly outcomes.
- Precise control over macrocycle structure and photoresponsive properties is achievable.
- Azobenzene-based systems offer significant potential for developing advanced adaptive materials.
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