Synthesis, 2D NMR analysis and liquid crystal function of 1,3-bis-(azomesogenes)-1,1,3,3-tetramethylsiloxane

Two new compounds (CH3(C6H4)N-2(C(6)H(3)A)COO(C6H4)OCH2-Si(CH3)(2))(2)O (1,2)(1,A=H;2,A=CH3) were synthesized and characterized by IR, H-1 NMR and elemental analysis. The chemical shifts and spin-spin-coupling constant of protons on the different benzene rings of the two title compounds were recorded on 2D NMR H-1-H-1 COSY, and the attribute of the peaks was specified. Analysis with polarizing microscope and DSC show that 1 has liquid crystal property while 2 has not. The electronic structure was calculated by AM1 method, and the relationship between electronic structure and liquid crystal function was also discussed.