研究目的
To evaluate the substituent effect at 5,5′ positions of a fused azobenzene–boron complex on electronic structures and optical properties, and to demonstrate narrower band gaps and unique electronic states in conjugated polymers.
研究成果
The study demonstrated that substituent effects at 5,5′ positions of BAz lead to narrower band gaps and unique electronic states with delocalized HOMO and localized LUMO. This tunability makes BAz a promising building block for optoelectronic devices, though weak emission in polymers suggests areas for further optimization.
研究不足
The luminescence from the polymers was very weak due to weak electronic interaction through 5,5′ positions, limiting their application in emissive devices. The study focused on bromine substituents and specific comonomers; other substituents or conditions were not explored.
1：Experimental Design and Method Selection:
The study involved synthesizing 5,5′-dibromo-substituted fused azobenzene–boron complex (BAz-5Br) and its copolymers with fluorene and bithiophene units using Migita–Kosugi–Stille cross-coupling polymerization. Optical and electrochemical measurements (UV–vis absorption, cyclic voltammetry) and theoretical calculations (density functional theory, DFT) were employed to analyze substituent effects and electronic properties.
2：Sample Selection and Data Sources:
Samples included BAz-H, BAz-4Br, BAz-5Br, model compounds (M-BAz-5BT, M-BAz-5FL), and copolymers (P-BAz-5BT, P-BAz-5FL). They were synthesized and characterized using NMR, MS spectra, and elemental analyses. Data were acquired from measurements in chloroform and dichloromethane solutions.
3：List of Experimental Equipment and Materials:
Equipment included UV–vis spectrophotometer, cyclic voltammetry setup with glassy carbon working electrode, Pt wire counter electrode, Ag/AgCl reference electrode, and gel permeation chromatography (GPC) for molecular weight estimation. Materials included chloroform, dichloromethane, nBu4NPF6 electrolyte, and various chemical reagents for synthesis.
4：Experimental Procedures and Operational Workflow:
Synthesis involved oxidation coupling, deprotection, and complexation reactions. Polymerization was carried out using Pd2(dba)3 and XPhos catalysts. Optical measurements were performed at 1.0×10?5 M concentration, and electrochemical measurements at 1.0×10?3 M with a scan rate of 0.1 V s?1. DFT calculations were done at B3LYP/6-311+G(2d,p) level.
5：0×10?5 M concentration, and electrochemical measurements at 0×10?3 M with a scan rate of 1 V s?DFT calculations were done at B3LYP/6-311+G(2d,p) level.
Data Analysis Methods:
5. Data Analysis Methods: Data were analyzed using UV–vis spectra for absorption maxima and molar extinction coefficients, cyclic voltammetry for energy level estimation (HOMO and LUMO), and DFT for molecular orbital analysis. Band gaps were calculated from optical and electrochemical data.
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