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Updated: Sep 9, 2025

Preparation of Contiguous Bisaziridines for Regioselective Ring-Opening Reactions
Published on: July 28, 2022
Solvent-dependent reactivity of azo-BF2 switches.
Qingkai Qi1,2, Heyifei Fu1, Lingya Peng3
1Department of Chemistry, Dartmouth College Hanover New Hampshire 03755 USA ivan.aprahamian@dartmouth.edu.
New azo-BF2 photoswitches with naphthalene modifications show tunable NIR light response. Solvent choice dictates reactivity, leading to either boron difluoride hydrazone fluorophores or solvolysis, crucial for developing advanced molecular devices.
Area of Science:
- Materials Science
- Organic Chemistry
- Photochemistry
Background:
- Azo-BF2 complexes are visible and near-infrared (NIR) light-activated photoswitches.
- Their photophysical properties and solution-state reactivity require further investigation for advanced applications.
Purpose of the Study:
- Synthesize and characterize novel azo-BF2 analogues with dimethylamine-substituted naphthalene moieties.
- Investigate the impact of π-system expansion on photophysical and photoswitching properties.
- Elucidate the stability and solvent-mediated reactivity of these photoswitches.
Main Methods:
- Synthesis and characterization of two azo-BF2 analogues.
- Photophysical property measurements.
- Solvent-dependent stability studies (solvolysis and 1,2-BF2 shift).
Main Results:
- Switch 1 exhibits NIR absorption (700 nm activation).
- Switch 2 shows improved photostationary state due to enhanced absorption band separation.
- Polar aprotic solvents induce a 1,2-BF2 shift, forming fluorophores.
- Polar protic solvents cause solvolysis to the starting hydrazone.
Conclusions:
- Solvent donor number influences 1,2-BF2 shift in aprotic solvents.
- Solvent hydrogen-bond donation capability dictates solvolysis in protic solvents.
- Insights guide the design of efficient NIR-responsive azo-BF2 photoswitches for smart materials.
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