Microwave-assisted solvent-free catalyzed synthesis and luminescence properties of 1,2,4,5-tetrasubstituted imidazoles bearing a 4-aminophenyl substituent

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• 作者：Liu-qing Yan ; Yao Chen ; Xiao-fu Sun ; Mao-jun You ; Xiao-dong Chen…
• 关键词：Tetrasubstituted imidazole ; Microwave radiation ; H3[PW12O40] ; Solid support SiO2 ; Solvent free ; Luminescence property
• 刊名：Chemical Papers
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：71
• 期：3
• 页码：627-637
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Chemistry/Food Science, general; Industrial Chemistry/Chemical Engineering; Biochemistry, general; Medicinal Chemistry; Materials Science, general; Biotechnology;
• 出版者：Springer International Publishing
• ISSN：1336-9075
• 卷排序：71

文摘

A solvent-free microwave-assisted four-component synthesis of 1,2,4,5-tetrasubstituted imidazoles bearing a 4-aminophenyl substituent was studied by condensation of p-phenylenediamine, aryl diketone, benzaldehyde derivatives and ammonium acetate in the presence of solid support silica gel and catalyst Keggin-H₃[PW₁₂O₄₀]. The effects of four components molar ratio along with catalyst loading, irradiation time on the yields were investigated. Also, the structures of synthesized compounds were characterized by FT-IR, HRMS, 1H NMR and 13C NMR spectroscopy. Furthermore, their ultraviolet–visible maximum absorption, liquid fluorescence emission maximum and quantum yields were, respectively, measured in 0.05 M H₂SO₄ aqueous solution and in dichloromethane. Simultaneously, solid fluorescence spectra were determined in the powder state. The relationships between the optical behavior and the polarity of the solvents for some compounds were assessed. The results showed that the fluorescence quantum efficiency was increased by introducing amino phenyl in comparison with benzyl on 1-position of trisubstitued imidazoles. The compounds synthesized were sensitive to the polarity of the solvents.