长链紫精类化合物的合成及其电致变色与液晶性质的研究

紫精类化合物是一类具有4,4’-联吡啶盐结构或类似结构的有机小分子，能够在氧化态和还原态下呈现出不同的颜色。因为这类化合物具有合成路线简单、结构可修饰性强、导电性能优异等特点，所以其在电致变色领域和液晶领域内均得到了广泛的关注。虽然关于紫精类化合物的共轭结构对其电致变色性质影响的报道已有大量刊载，但是关于紫精类化合物两端烷基链长度的变化对其电致变色性质及液晶性质的影响仍然有待探索。

通过在紫精分子传统的联吡啶骨架结构中插入噻吩环并对其两侧吡啶环上N原子进行不同长度烷基链修饰的方法，本论文成功合成出了一系列具有不同烷基链长度的2,5-二（4-吡啶）噻吩（PTP）型紫精分子。本论文以6-PTP-m系列紫精分子为电致变色材料制备了一批凝胶电致变色器件，其中电致变色器件6-PTP-6拥有这批器件中最优异的综合性能，其着色态透过率仅为4.7 %，着色响应时间与褪色响应时间仅分别为1.6 s和9.2 s，光学对比度高达76.3 %，着色效率高达455.4 cm²/C，器件在循环工作5000次后的光学对比度衰减量仅为2.52 %。对6-PTP-m系列电致变色器件的各项性能进行综合比较后发现，随着紫精材料烷基链长度的增加，相应器件的着色态透过率整体呈上升趋势，光学对比度整体呈下降趋势，而循环稳定性整体上也呈下降趋势。此外，这一系列PTP型紫精分子的液晶性质表征结果说明，只有当PTP型紫精材料两端的烷基链长度足够长时，其才具备液晶性质。并且这批紫精材料的液晶相温度区间将随着分子两端烷基链长度增加而变宽，其中紫精材料7-PTP-10拥有这批紫精材料中最低的熔点（37.4 °C），紫精材料9-PTP-11拥有这批紫精材料中最宽的液晶相温度区间（64.8 °C -127.6 °C）。具有对称烷基链取代结构的PTP型紫精材料通常在同系列紫精材料中具有更高的熔点和相变焓，且随着PTP型紫精材料两端烷基链结构不对称性的增加，其熔点及相变焓会在整体上将呈现出下降的趋势。

本论文初步探究了紫精分子两端烷基链长度的变化对其电致变色性质与液晶性质的影响，所得结论有望为今后紫精类多功能光电材料的分子设计提供一定的帮助。

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