研究目的
To control conformation in molecules in the excited state through harvesting negative hyperconjugation, specifically using the 2,3,1,4-benzodiazadiborinane scaffold.
研究成果
The study demonstrates that excited state conformations can be controlled by tuning solvent polarity and spatial confinement. The 2,3,1,4-benzodiazadiborinane framework shows dual fluorescence due to conformational changes from negative hyperconjugation, which can be inhibited in solid matrices or polar solvents. This provides insights for designing catalytic transformations, molecular materials, and biological processes involving electronic excitations.
研究不足
The synthesis of B,N-acenes is difficult, involving multiple steps, harsh conditions, and reliance on expensive or toxic catalysts. Quantum yields are low (less than 1%). Unsymmetrically substituted azobenzenes gave lower yields. The method may not be general for all substituents, as nitro-substituted compounds did not yield products.
1：Experimental Design and Method Selection:
The study involved designing a system to favor specific conformers in the excited state using negative hyperconjugation. A new synthetic protocol was developed for 2,3,1,4-benzodiazadiborinanes. Computational studies at the CAM-B3LYP/cc-pVTZ level of theory were used to optimize ground and excited state structures and rationalize electronic excitations. Photochemical studies included UV-Vis and fluorescence spectroscopy to observe dual emission.
2：Sample Selection and Data Sources:
Samples included synthesized 2,3,1,4-benzodiazadiborinanes (e.g., 3a-3g) from reactions of lithium o-phenylbisborate with hydrazines or azobenzenes. Azobenzenes were used as air-stable building blocks. Solvents of varying polarity (cyclohexane, toluene, dichloromethane, THF) were employed.
3：List of Experimental Equipment and Materials:
Equipment included instruments for UV-Vis and fluorescence spectroscopy, sublimation apparatus, and computational software (Newton-X). Materials included lithium o-phenylbisborate, hydrazines, azobenzenes, TMSCl, solvents (toluene, THF), and PMMA for thin films.
4：Experimental Procedures and Operational Workflow:
Synthesis involved reacting lithium o-phenylbisborate with hydrazines or azobenzenes in optimized conditions (e.g., toluene at 60°C for 6h). Products were purified by sublimation. Photophysical measurements were conducted in solution and solid state (frozen cyclohexane, PMMA films). Data collection included absorption and emission spectra, quantum yields, and computational simulations.
5：Data Analysis Methods:
Data were analyzed using computational methods (CAM-B3LYP/cc-pVTZ for geometry optimization, Wiberg bond orders), and experimental spectra were compared with computed ones. Statistical analysis of yields and spectral changes with solvent polarity was performed.
独家科研数据包，助您复现前沿成果，加速创新突破
获取完整内容
