Novel green synthetic approach for liquid crystalline materials using multi-component reactions

Abstract

We report the synthesis of disk-shape liquid crystalline materials using multi-component reactions (MCR). Two new series, 3,9-di(3′,4′,5′-tris-alkyloxy)phenyl-2,3,4,8,9,10-hexahydronaphtho[1,2-e:5,6-e']bis([1,3]oxazine) and 3,10-di((3′,4′,5′-tris-alkyloxy)phenyl)-2,3,4,9,10,11-hexahydronaphtho[1,2-e:4,3-e']bis([1,3]oxazine) synthesized by coupling either 2,3-dihydroxy naphthalene or 2,6-dihydroxy naphthalene with 3,4,5-tris-O-alkylated anilines in a solvent free condition. The molecular structure of the new materials was confirmed using 1H NMR, 13C NMR and CHN elemental analysis. The phase behavior investigated using polarizing optical microscope (POM) and differential scanning calorimetry (DSC) experiments. All the materials exhibit room temperature discotic nematic (ND) during the cooling cycles as confirmed by X-ray diffraction studies. This synthetic approach provides multiple advantages such as high atom economy (AE), short reaction time, gentle reaction condition, simple workup, and do not require column chromatography purification, additionally this could pave a new way in the synthesis of liquid crystalline compounds.