Development of thermoresponsive near-ultraviolet photoluminescent liquid crystals using hexyloxy-terminated fluorinated tolane dimers connected with an alkylene spacer
Development of thermoresponsive near-ultraviolet photoluminescent liquid crystals using hexyloxy-terminated fluorinated tolane dimers connected with an alkylene spacer
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DOI：
10.1016/j.molliq.2022.119755
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发表时间：
2022-06
影响因子：
6
通讯作者：
S. Yamada;Eiji Uto;T. Sakurai;T. Konno
中科院分区：
文献类型：
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作者：
S. Yamada;Eiji Uto;T. Sakurai;T. Konno
本研究展示了新型温敏近紫外（UV）光致发光液晶（LC）分子的设计和发展，通过合成的己氧基封端的氟化二苯乙炔二聚体连接不同长度的亚烷基间隔。采用Sonogashira交叉偶联和Mitsunobu型醚化反应的简单三步反应方案合成了二聚体。相变行为的研究表明，由戊烯间隔基连接的氟化二苯乙炔二聚体具有两个中间相，即近晶A相（SmA）和非晶A相。此外，光物理评价表明，二聚体表现出近紫外光致发光（PL）的效率高达0.19的结晶（Cr）相，虽然近紫外PL立即淬灭在溶液相中。通过Cr → SmA相变导致分子聚集体的结构变化导致其PL进一步蓝移25 nm。这些发现为设计可用作热敏材料的温敏近紫外PLLC分子提供了合适的途径。
This study demonstrates the design and development of novel thermoresponsive near-ultraviolet (UV) photoluminescent liquid-crystalline (LC) molecules via the synthesis of hexyloxy-terminated fluorinated tolane dimers connected by various lengths of alkylene spacers. The dimers were synthesized using a facile three reaction scheme involving Sonogashira cross-coupling and Mitsunobu-type etherification reactions. The investigation of phase transition behavior revealed that the fluorinated tolane dimer connected by a pentylene spacer exhibited two mesophases, namely, the smectic A (SmA) and nematic phases. Furthermore, photophysical evaluations revealed that the dimers exhibit near-UV photoluminescence (PL) with an efficiency of up to 0.19 in the crystalline (Cr) phase, although the near-UV PL is immediately quenched in the solution phase. The structural change in the molecular aggregates via the Cr → SmA phase transition led to the further blueshift of their PL by 25 nm. These findings offer a suitable pathway for designing thermoresponsive near-UV PLLC molecules applicable as thermosensing materials.