Synthesis and characterization of liquid crystalline diethanolamine-based dendrimers

Three generations of diethanolamine-based dendrimers containing nitroazobenzene were synthesized. Firstly, G(1) was prepared by the diazotation of p-nitroaniline, and then the obtained salts reacted with n-phenyl-2,2'-iminodiethanol. The reaction of hydroxyl groups of diethanolamine of G(1) and G(2) with acryloyl chloride resulted in G(1.5) and G(2.5). Then, G(2) and G(3) were synthesized using Michael addition of amino group of diethanolamine and G(1.5) and G(2.5). The Williamson etherification and azo-reaction were employed in the preparation of the mesogenic unit 4-[4-(6-bromohexyloxy)phenylazo]nitrobenzene (N-6-Br). Secondly, mesogen-functionalized dendrimers were synthesized via the coupling of the hydroxyl group of G(1), G(2), G(3), and bromine from mesogenic units (N-6-Br). The polarizing optical microscopy (POM) and differential scanning calorimetry (DSC) were used for the investigation of the liquid crystalline properties of the mesogen-functionalized dendrimers. The structures of obtained compounds were investigated using common spectroscopy methods and CHN analysis. Copyright (C) 2009 John Wiley & Sons, Ltd.