Studies on carbosilane liquid crystalline dendrimer of the second generation - Containing 36 4-hexyloxyazobenzene groups in its periphery

The divergent synthesis of a new carbosilane liquid crystalline(LC) dendrimer of the second generation(D2) was described. Thirty-six 4-hexyloxyazobenzene groups (M3) were used as mesogenic fragments and attached to its periphery. The structure and properties of D2 were characterized by elementary analysis, H-1 NMR, MALDI-TOF-MS, IR, UV, polarizing optical micrograph, DSC and WAXD. It is argued that mesophase of nematic type is realized. It is shown that the mesophase type of the dendrimer D2 and D1 essentially depends on the chemical nature of the mesogenic groups and is the same as that of mesogenic unites. The phase behavior of D2 in LC state is K90N105H11N75K. The melting point of D2 decreases 26-33 degreesC than that of M3, the temperature at its clear point decreases 3-15 degreesC than that of M3 and its mesophase region is enlarged 11-30 degreesC than that of M3. The melting point of D2 decreases 2-3 degreesC than that of D1, the temperature at its clear point decreases 11-21 degreesC than that of D1 and its mesophase region decreases 8-19 degreesC than that of D1.