ABSTRACT

The synthesis and characterisation of tetrasubstituted tetrathiafulvalenes (TTFs) 1a–1c, which bear photoresponsive 4ʹ-cyanoazobenzenyl units, are described. These units were linked to the TTF core through spacers of different lengths. All synthesised compounds displayed mesogenic phases over a wide temperature range and no crystallisation, but vitrified to form glassy mesogens during cooling from the isotropic melt. Compound 1a with a short spacer (n = 6) exhibited enantiotropic nematic and smectic A mesophases. In contrast, compound 1b showed monotropic smectic A and oblique columnar phases. However, compound 1c with the longest spacer (n = 10) only possessed an oblique columnar phase. The results for this compound series showed that the molecular packing pattern depended on the spacer length and that cool-crystallisation was observed upon further heating. Furthermore, cyclic voltammetry and impedance tests confirmed that compound 1a has potential applications in organic semiconductor materials.

A new series of compounds derived from heterocycle TTF was successfully designed and synthesised using simple synthetic methods. All compounds formed glassy mesogens with an above-ambient glass transition temperature during cooling from the isotropic melt. With increasing spacer length, the self-assembled structures changed from Lam to Col_o. These TTF‐based LCs, in combination with good electron-donating properties and the inherent optoelectronic properties of azobenzene, might be attractive new candidates for organic optoelectronic devices.

摘要

描述了具有光响应性4′-氰基偶氮苯并烯单元的四取代四硫富瓦烯（TTF）1a-1c的合成和表征。这些单元通过不同长度的间隔子连接到TTF核心。所有合成的化合物在很宽的温度范围内均显示介晶相，没有结晶，但在各向同性熔体冷却过程中玻璃化形成玻璃态介晶。具有短间隔基（n = 6）的化合物1a表现出对映向列型和近晶A中间相。相反，化合物1b表现为单向近晶A相和倾斜的柱状相。但是，化合物1c间隔最长的（n = 10）仅具有倾斜的柱状相。该化合物系列的结果表明，分子堆积图案取决于间隔物的长度，并且在进一步加热时观察到冷结晶。此外，循环伏安法和阻抗测试证实化合物1a在有机半导体材料中具有潜在的应用。

使用简单的合成方法成功设计并合成了一系列来自杂环TTF的化合物。从各向同性熔体冷却期间，所有化合物均形成玻璃态液晶元，其玻璃化转变温度高于环境温度。随着间隔物长度的增加，自组装结构从Lam变为Col _o。这些基于TTF的LC结合良好的供电子特性和偶氮苯固有的光电特性，可能是有机光电器件的有吸引力的新候选产品。