Reversible Change between Excimer and Monomer Forms of Perylene Induced by Water Absorption and Dehydration of Poly-N-isopropylacrylamide Gel
Reversible Change between Excimer and Monomer Forms of Perylene Induced by Water Absorption and Dehydration of Poly-N-isopropylacrylamide Gel
复制标题
聚-N-异丙基丙烯酰胺凝胶吸水和脱水引起苝准分子和单体形态的可逆变化
DOI：
10.1021/acs.jpcb.0c11418
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发表时间：
2021
期刊：
影响因子：
3.3
通讯作者：
S. Ozeki
中科院分区：
文献类型：
--
作者：
A. Hamasaki;K. Kubo;M. Harashima;A. Katsuki;S. Ozeki
已经报道了几种来源于二萘嵌苯的受激准分子态的荧光图案，但其中大多数是从刚性形式如晶体或嵌在硬聚合物中的二萘嵌苯获得的。我们观察到，由聚-N-异丙基丙烯酰胺凝胶的水的吸收，其中含有？分子，这是不固定的凝胶框架通过化学键合？激基缔合物发射。我们提出，这种发射的出现，因为疏水性的二萘嵌苯分子不能溶于水，形成聚集体。在凝胶脱水时，二萘嵌苯聚集体很快消失，发光恢复到单体的发光。在脱水环境中，苝迅速分散在凝胶网络中。换言之，二萘嵌苯的固-液相分离是通过将水吸收到凝胶中而引起的，并且二萘嵌苯在脱水时溶解在凝胶中。由于凝胶的外部总是处于水性环境中，因此二萘嵌苯将半永久地保留在凝胶中。因此，单体发射和激基缔合物发射可以可逆地和重复地切换。
Several fluorescence patterns derived from the excimer states of perylene have been reported, but most of these have been obtained from rigid forms such as crystals or for perylene embedded in hard polymers. We observed perylene excimer emission on absorption of water by a poly-N-isopropylacrylamide gel containing perylene molecules, which were not fixed to the gel framework by chemical bonding. We propose that this emission arises because the hydrophobic perylene molecules cannot dissolve in water and form aggregates. The perylene aggregation was quickly lost on dehydration of the gel, and the luminescence reverted to that of the monomer. In a dehydrated environment, perylene was rapidly dispersed in the gel network. In other words, solid–liquid phase separation of perylene was induced by uptake of water into the gel, and perylene dissolved in the gel on dehydration. Because the outside of the gel is always in an aqueous environment, perylene will remain semipermanently in the gel. Therefore, monomer emission and excimer emission can be switched reversibly and repeatedly.