Four triphenyl imidazole compounds including 4-(4,5-diphenyl-1H-imidazol-2-yl)benzaldehyde (2a), 4-[4,5-bis(3-nitrophenyl)-1H-imidazol-2-yl]benzaldehyde (2b), 4-(1-benzyl-4,5-diphenyl-1H-imidazol- 2-yl)benzaldehyde (2c) and 4-[1-benzyl-4,5-bis(3-nitrophenyl)-1H-imidazol-2-yl]benzaldehyde (2d) have been synthesized. All the compounds have been identified by FT-IR, NMR and MS techniques. Single crystal of 2c suitable for X-ray measurement was obtained from ethyl acetate/petroleum ether solvent, which belongs to a triclinic system with space group and cell parameters of a＝0.73796(15) nm, b＝0.90136(18) nm, c＝1.6644(3) nm, α＝86.87(3)°, β＝78.25(3)°, γ＝89.94(3)°, V＝1.0822(4) nm³, D_c＝1.272 g/cm³, Z＝2, F(000)＝436, μ＝0,077 mm^－1, R₁＝0.0459, wR₂＝0.1303. Their ultraviolet and fluorescence properties have been studied. The results show that the nitro and benzyl groups influence the absorption and emission spectra of these compounds. The two groups induce blue-shift in the ultraviolet spectra. But in the fluorescence spectra, the benzyl group generates blue-shift while the nitro group causes red-shift. The fluorescence lifetime of 2a and 2c in different solvents has been measured. These results are the base of studying nonlinear optical properties such as two-photon absorption and two-photon fluorescence.

Key words: triphenyl imidazole, lophine, crystal structure, ultraviolet, fluorescence