基于季戊四醇的三代硅碳烷液晶树状物研究

Study on a Novel Pentaerythritol-based Carbosilane Liquid Crystalline Dendrimer of the Third Generation

用发散法合成了季戊四醇-四烯丙基醚为核、周边含硝基偶氮苯介晶基元(M-NO2)端基的新型三代硅碳烷液晶树状物PCSi-3G-NO2,并利用元素分析、红外光谱(IR)、核磁共振(NMR)、偏光显微镜(POM)、差示扫描量热法(DSC)和X射线衍射(XRD)进行表征.PCSi-3G-NO2显示胆甾相和近晶SE相,其液晶相行为是K57SE115I100Ch80SE53K.而对应的介晶基元M-NO2显示向列相,二者在熔点、清亮点和液晶态温区等方面差别较大.

The divergent synthesis of a novel pentaerythritol-based carbosilane liquid crystalline dendrimer PCSi-3G-NO2 was described. A terminal Si-Cl functional carbosilane dendrimer of the third generation based on pentaerythritol was used as dendritic scaffold and subsequently functionalized with 4-nitroazobenzene (M-NO2). Structure and properties of PCSi-3G-NO2 were characterized by elemental analysis, H-1 NMR, IR, polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). PCSi-3G-NO2 is cholesteryl and smectic E liquid crystal, different from the mesogenic unit M-NO2 that shows nematic phase. They are different in terms of the melting point, the clearing point and the temperature region of mesogenic phase.