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摘要
Two discotic liquid crystalline compounds, 6,7,10,11-tetra-pentyloxytriphenylene-1,4-dione and 6,7,10,11-tetra-heptyloxy-triphenylene-1,4-dione were synthesized and characterized. The synthesis consisted of two key steps: the preparation of 1,4-dimethoxy-6,7,10,11-tetra-alkoxytriphenylene and the oxidation to form the target compounds. In the latter step, the reaction was significantly improved using sodium nitrite in trifluoroacetic acid as an oxidant, resulting in an enhanced overall reaction yield and dramatically reduced reaction time. Both products show liquid crystalline phases, which were investigated using polarized optical microscopy and thermal analysis. The product with a longer side chain displayed a broader liquid crystal phase temperature range and favored a faster structure formation at low temperature. In addition to absorption at 272 nm, which is commonly observed in triphenylene-based discotic liquid crystals, the optical absorption of both compounds extends to the visible range, with extra absorption observed at 630 nm.
