| 摘要: | 設計並合成出一系列2,5-bis(3,4,5-trialkoxyphenyl)-1,3,4-oxadiazoles 與4-Alkyl(Aryl)-3,5-bis(3,4,5-trialkoxyphenyl)-4H-1,3,4-triazoles的有機雜環液晶化合物，這些雜環化合物均以不飽和的1,3,4-oxadiazole及1,2,4-triazole五環做為中心結構，經由3,4,5-Trialkoxybenzoic acid N-(3,4,5-Trialkoxybenzoyl)hydrazides的合環反應即可獲得，所得之所有化合物皆經由1H- and 13C-NMR光譜和元素分析加以鑑定其結構與純度，而液晶現象的觀察、分析則藉助熱分析儀與偏光顯微鏡來判斷。經由觀察與實驗，會形成結晶相的化合物，主要與分子結構中柔軟alkoxy側鏈基數目的多寡有關；而會形成具有液晶現象的的化合物，則和分子結構上柔軟alkoxy側鏈基的多寡及中心結構上氮原子與氧原子的極性有相當的關係，這兩個系列的化合物，其液晶化合物皆為hexagonal columnar(Colh) phases 的盤狀型液晶分子，其中有數個側鏈碳數較短者，為室溫型液晶。 The synthesis, characterization and mesomophic properties of a new type of liquid crystalline compounds, 2,5-bis(3,4,5-trialkoxyphenyl)-1,3,4-oxadiazoles and 4-alkyl(aryl)-3,5-bis(3,4,5-trialkoxyphenyl)-4H-1,3,4-triazoles are reported. These heterocyclic compounds were derived from unsaturated 1,3,4-oxadiazoles and 1,2,4-triazoles as the core group, and obtained by condensation reaction of 3,4,5-trialkoxybenzoic acid N-(3,4,5-Trialkoxybenzoyl)hydrazides. These compounds were characterized by 1H- and 13C-NMR spectroscopy and elemental analysis. The mesomorphic properties of these compounds was characterized and studied by different scanning calorimetry(DSC) and polarized optical microscope.The primation of mesophases was found to be dependent of the numbers of alkoxy sidechains attached. Some compounds exhibited hexagonal columnar(Colh) phases, however, the others formed crystalline phases regardless of the carbon length on the sidechains. The compounds with shorter carbon sidechains were room temperature liquid crystals. Thepolar induction by nitrogen or/and oxygen atoms on the heterocyclic core ring might be responsible for the formation and beter observed mesomorphic properties in this type of compounds. |
