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One- and two-electron reduction of triarylborane-based helical donor-acceptor compounds.
Xiangqing Jia1, Jörn Nitsch1, Zhu Wu1
1Institut für Anorganische Chemie and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany todd.marder@uni-wuerzburg.de.
Chemical Science
|October 18, 2021
Summary
Chemical reduction of helicene-based amines forms monoanions and biradicaloid dianions. These species exhibit unique electronic properties, including temperature-dependent triplet state populations, confirmed by various spectroscopic and computational methods.
Area of Science:
- Organic Chemistry
- Materials Science
- Photochemistry
Background:
- Helicene derivatives are known for their unique structural and electronic properties.
- Boron and amine functionalities can significantly influence molecular electronic behavior.
Purpose of the Study:
- To investigate the chemical reduction of novel helicene-based amines containing dimesitylboryl and di-p-tolylamine groups.
- To characterize the electronic structures and properties of the resulting radical anions and biradicaloids.
Main Methods:
- One- and two-electron chemical reductions.
- Single-crystal X-ray diffraction.
- Electron Paramagnetic Resonance (EPR) spectroscopy.
- UV/vis-NIR spectroscopy.
- Density Functional Theory (DFT) calculations.
Main Results:
- One-electron reduction yielded monoanions with charge delocalization across helicene rings and boron p-orbitals.
- Two-electron reduction produced open-shell biradicaloid dianions.
- Small singlet-triplet gaps were observed, leading to temperature-dependent triplet state populations.
Conclusions:
- The studied helicene derivatives can be readily reduced to stable radical anions and biradicaloids.
- These reduced species exhibit intriguing electronic properties relevant to organic electronics and spintronics.
- The interplay between the helicene core, boron atom, and amine group dictates the observed electronic behavior.
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