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The triphenylne derivatives are chosen as one of negative birefringent materials to form a compensator for widening the viewing angle.Calamatic liquid crystal molecules have positive birefringence in refractive property.This anisotropy causes light leakage and results in narrow range of the viewing angle of the LCD.In our study,a series of novel discotic triphenylene derivertives bearing one triphenylene discogen as core and three cyano-biphenyl moities was synthesized and their thermal behaviors were studied using polarizing optical microscope,differential scanning calorimeter and X-ray diffraction.It was found that those molecules containing even numbers of methylene spacers showed nematic phase.After being mixed with MMA (methyl methacrylate),they also showed nematic phase at the mesophase temperature range.The hybrid mode alignment of the molecules can be fixed by photopolymerization of acryloyl moieties.If the alignment of the discotic molecules can be freely controlled,a new area of optically anisotropic film will be produced.