Reversible bulk-phase change of anthroyl compounds for photopatterning based on photodimerization in the molten state and thermal back reaction.
Reversible bulk-phase change of anthroyl compounds for photopatterning based on photodimerization in the molten state and thermal back reaction.
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DOI：
10.1021/am400111q
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发表时间：
2013-03
影响因子：
9.5
通讯作者：
H. Kihara;Masaru Yoshida
中科院分区：
文献类型：
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作者：
H. Kihara;Masaru Yoshida
合成了2-蒽酰基和9-蒽酰基酯类化合物作为新型的有机配位化合物。它们的体相变化（我们使用“体相变化”作为完整的相变在质量的材料既不是在表面上，也不是在本研究中的少量）引发的光二聚在熔融条件下（熔融光二聚）和随后的热回反应进行了研究。所有的蒽酰基化合物的熔点均低于约100 ℃。160 °C的温度下，并且它们通过在比它们各自的熔点高0.15 °C的温度下的UV照射几乎定量地转化为相应的光二聚体。通过光化学反应，我们发现了两种不同的体相变化行为。两个的蒽基化合物保持各向同性和熔融光二聚过程中失去流动性。所得到的光二聚体在室温下表现出稳健的固态非晶相。与此相反，其他三个蒽酰基化合物在熔融光二聚过程中显示结晶。即使在高温下，所得的光二聚体也从各向同性变为结晶相。各种实验表明，体相的光二聚体的影响，而不是由区域异构体的存在，但在光照射温度下，其流动性。后三种光二聚体保持足够的流动性，反映了它们在光照射温度下的等温结晶发生的高分子迁移率。另外两种产物由于低流动性而不能结晶，导致无定形相。我们还发现，所有的光二聚体通过热逆反应恢复到相应的单体，并恢复其初始的光化学和热性能。利用这些可逆的体相变化的蒽基化合物，我们成功地证明了在不仅负的图像，但也积极的，有序和无序相之间的光学对比度的基础上，双折射atterning。
As new organic materials for rewritable photopatterning, 2-anthroyl and 9-anthroyl ester compounds were synthesized. Their bulk-phase changes (we use "bulk-phase change" as complete phase change in a mass of a material neither in a surface nor in a small quantity in this study) triggered by photodimerization under melting conditions (melt-photodimerization) and subsequent thermal back reactions were investigated. All the anthroyl compounds exhibited melting points lower than ca. 160 °C, and they were nearly quantitatively converted to the corresponding photodimers by UV irradiation at temperatures of ∼5 °C higher than their respective melting points. We found that there were two kinds of bulk-phase change behaviors through the photoreaction. Two of the anthroyl compounds remained isotropic and lost fluidity during the melt-photodimerization. The obtained photodimers exhibited robust solid-state amorphous phases at room temperature. In contrast, the other three anthroyl compounds showed crystallization during the melt-photodimerization. The resulting photodimers changed from isotropic to crystalline phases, even at high temperature. Various experiments revealed that the bulk phase of the photodimers was affected not by the existence of regioisomers but by their fluidity at the photoirradiation temperature. The latter three photodimers retained enough fluidity, reflecting their high molecular mobilities at the photoirradiation temperature at which the isothermal crystallization occurred. The other two products were not able to crystallize due to low fluidity, resulting in amorphous phases. We also found that all the photodimers reverted to the corresponding monomers by thermal back reaction and recovered their initial photochemical and thermal properties. Using these reversible bulk-phase changes of the anthroyl compounds, we successfully demonstrated rewritable photopatterning in not only negative images but also positive ones, based on the optical contrast between the ordered and disordered phases.