The title compound [CH3(C6H4)N2O(C6H4)COO(C6H4)OCH2Si (CH3)2]2O was synthesized and characterized by IR，1^H NMR and elemental analysis. The crystal structure was determined by single crystal X-ray diffraction techniques. The crystal belongs to the monoclinic space group P21/c with a=1.7557(1), b=1.0938(9), c=2.3300(1)nm, β=105.6(6) °, V=4.3116 nm^3, Mr=855.07, Z=4, Dc=1.317 g/cm^3, μ=6.335 cm^-1, F (000)=900. Final R=0.0837, Rw=0.0913 . The flexible group of tetramethylsiloxane and the rigid azoxybenzene functinality form a neat-polymer of ABA structure, in which the two rigid mosomorphic chain shafts are parallelt to each other with L/D=4.23. The phase changing parametters of the liquid crystal are K 174.4N 226.8 Ⅰ. The relationship between the structure and phase changing behavior of the liquid crystal of this kind of compounds is also discussed.

Key words: BENZENE AZO COMPOUNDS, SILOXANE, OLIGOMER, CRYSTAL STRUCTURE, LIQUID CRYSTAL, INFRARED SPECTROPHOTOMETRY, PROTON MAGNETIC RESONANCE SPECTROMETRY, PHASE TRANSFORMATION