Mono-Disperse Triphenylene Discotic Liquid Crystal Oligomers Synthesized by Click Chemistry

Yue-Feng      Bai; Ke-Qing      Zhao; Ping      Hu; Bi-Qin      Wang; Carl      Redshaw

doi:10.2174/1385272811317080012

Abstract

Discotic liquid crystals, as new organic semiconductors, possess not only the ability to self-organize to a highly ordered columnar mesophase, but also possess high charged carrier mobility and solution processed characteristic. The progress of synthetic organic chemistry and new molecular designing ideas will result in improved discotic liquid crystalline semiconductors. In this report, we have investigated the CuI–Et3N catalyzed click reaction between terminal alkyne and azide, both of which contain a triphenylene moiety. Series new mono–dispersed triphenylene discotic liquid crystal oligomers containing the 1,4–disubstituted–1,2,3–triazole ring have been synthesized. Their structures have been fully characterized by FT-IR, 1H and 13C NMR spectroscopy, MALDI Mass spectrometry. The monodispersity of oligomers has been confirmed by the result of GPC. Their thermal stability and liquid crystalline properties have been studied by thermal gravimetric analysis (TGA), polarized optical microscopy (POM), differential scanning calorimetry (DSC), and X–ray diffraction (XRD). The results demonstrated that all oligomers possessed the hexagonal columnar mesophase, and were room temperature liquid crystals.

Keywords: Click chemistry, Cu(I) catalyzed alkyne azide cycloaddition, CuAAC reaction, discotic liquid crystal, triphenylene, oligomer, columnar mesophase, monodisperse.