Synthesis and optical behaviors of 2-(9-phenanthrenyl)-, 2-(9-anthryl)-, and 2-(1-pyrenyl)-1-alkylimidazole homologues

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Molecular and biomolecular spectroscopy, 2009-09, Vol.74 (1), p.233-242
• Main Authors: Yan, Yun-Nan, Lin, Dan-Yan, Pan, Wen-Long, Li, Xiu-Ling, Wan, Yi-Qian, Mai, Yu-Liang, Song, Hua-Can
• Format: Article
• Language: English
• Subjects: 2-Arylbenzimidazole homologues; Absorption spectra; Emission spectra; Fluorescence lifetime; Quantum yields; Synthesis
• ISSN: 1386-1425
• DOI: 10.1016/j.saa.2009.06.020

Eight 2-(9-phenanthrenyl)-, 2-(9-anthryl)- and 2-(1-pyrenyl)-1-alkyl-benzimidazole compounds, three 2-(9-anthryl)-1-alkylphenanthroimidazole compounds and five 4,5-diphenyl-1-alkyl-2-(9-anthryl)imidazole compounds were synthesized by alkylation reactions of the corresponding benzimidazole, phenanthroimidazole or imidazole compounds. 2-(10-Bromo-9-anthryl)-1-alkyl-benzimidazole compounds were prepared by bromination reaction of 2-(9-anthryl)-1-alkylbenzimidazole compounds. All the synthesized compounds were characterized by elemental analysis, 1H NMR, 13C NMR, MS or HRMS; their absorption coefficients ( ɛ), maximum absorption λ amax, fluorescence emission maximum λ em, Stokes shifts and fluorescence quantum yields ( Φ F) in ethyl acetate were determined; their fluorescent lifetimes ( T 1 and T 2) were measured in ethyl acetate and in solid state, respectively. The crystal structure of 2-(9-anthryl)-1- n-butyl-4,5-diphenylimidazole ( 12a) was determined to be triclinic, space group P-1 types, using single crystal X-ray crystallography technique. The results showed that these compounds exhibited moderate fluorescence-emission abilities and higher solubility in most organic solvents than their corresponding starting materials. The relationships between the optical behaviors and structures for these compounds were discussed.