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

• Published in: Chemical papers Vol. 71; no. 3; pp. 627 - 637
• Main Authors: Yan, Liu-qing, Chen, Yao, Sun, Xiao-fu, You, Mao-jun, Chen, Xiao-dong, Gu, Qiang, Zhang, Yu-min
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.03.2017; Springer Nature B.V
• Subjects: Ammonium acetate; Aqueous solutions; Aromatic compounds; Bearing; Benzaldehyde; Biochemistry; Biotechnology; Catalysis; Catalysts; Chemical synthesis; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Dichloromethane; Fluorescence; Industrial Chemistry/Chemical Engineering; Luminescence; Materials Science; Medicinal Chemistry; NMR spectroscopy; Optical properties; Original Paper; Phenylenediamine; Polarity; Quantum efficiency; Silica gel; Silicon dioxide; Solvents; Spectrum analysis; Sulfuric acid; Luminescence property; Microwave radiation; Solvent free; PW; H; ]; Solid support SiO; Tetrasubstituted imidazole; O
• ISSN: 2585-7290; 0366-6352; 1336-9075
• DOI: 10.1007/s11696-016-0051-1

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-H 3 [PW 12 O 40 ]. 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, 1 H NMR and 13 C NMR spectroscopy. Furthermore, their ultraviolet–visible maximum absorption, liquid fluorescence emission maximum and quantum yields were, respectively, measured in 0.05 M H 2 SO 4 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.