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Divalent Benzimidazolium-Based Axles for Self-Reporting Pseudorotaxanes
S Maryamdokht Taimoory1,2, Xiao Yu1, Ngong Kodiah Beyeh3
1Department of Chemistry and Biochemistry, University of Windsor, 401 Sunset Ave., Windsor, ON N9B 3P4, Canada.
The Journal of Organic Chemistry
|November 15, 2022
Summary
Benzimidazolium compounds show potential as building blocks for pseudopolyrotaxanes. Their optical properties change with concentration and solvent, enabling tunable behavior in supramolecular assemblies.
Area of Science:
- Supramolecular Chemistry
- Materials Science
- Computational Chemistry
Background:
- Benzimidazolium salts are explored for their unique structural and electronic properties.
- Pseudopolyrotaxanes are supramolecular structures with potential applications in materials science.
Purpose of the Study:
- To evaluate mono- and bisbenzimidazolium compounds as building blocks for pseudopolyrotaxane axles.
- To investigate the aggregation and photophysical behavior of these benzimidazolium compounds.
- To study the formation of pseudorotaxanes with dibenzyl-24-crown-8.
Main Methods:
- Experimental techniques: 1D/2D and diffusion-ordered NMR spectroscopy, mass spectrometry, UV-Vis and fluorescence spectroscopy.
- Computational modeling: Time-dependent density functional theory (TD-DFT).
- Variable conditions: Protonation state, solvent, and concentration were systematically varied.
Main Results:
- Benzimidazolium axles exhibit strong solvochromaticism, meaning their optical properties are highly dependent on the solvent.
- A pronounced concentration-dependent optical profile was observed, including self-quenching.
- Successful formation of [2]pseudorotaxanes with dibenzyl-24-crown-8 was confirmed.
Conclusions:
- Mono- and bisbenzimidazolium compounds are effective pseudopolyrotaxane axle building blocks.
- The photophysical behavior of these axles can be tuned by controlling protonation state, solvent, and concentration.
- The ability to form pseudorotaxanes with tunable optical properties opens avenues for novel supramolecular materials.
