Chromatic studies of a polymerizable diacetylene hydrogen bonding self-assembly: A "self-folding" process to explain the chromatic changes of polydiacetylenes
Chromatic studies of a polymerizable diacetylene hydrogen bonding self-assembly: A "self-folding" process to explain the chromatic changes of polydiacetylenes
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DOI：
10.1021/la990025f
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发表时间：
1999-05-25
期刊：
影响因子：
3.9
通讯作者：
Leblanc, RM
中科院分区：
文献类型：
--
作者：
Huo, Q;Russell, KC;Leblanc, RM
在本研究中，设计并合成了一种新的二乙炔化合物(PDATAZ)，该化合物在空气-水界面或与巴比妥酸(BA)或三聚氰酸(CA)在固相中容易形成互补氢键自组装。PDATAZ及其与BA或CA组装的光聚合研究揭示了聚二乙炔的显色性质。研究发现，聚二乙炔的变色性取决于聚合链是否能呈线性链状。随着聚合物链长度的不断增加，由于聚合物链内单键的自由旋转，原有的线型聚烯烃主链开始“自我折叠”成“之”字形结构。沿着聚乙炔主链的有效的pi电子离域被这一过程中断，导致聚二乙炔的颜色从蓝色变为红色。如果侧链的极性基团之间存在较强的分子间相互作用，如二乙炔两亲分子中的三氨基三嗪(TAZ)部分与其互补组分之间存在互补的氢键网络，则限制了侧链的运动，抑制了聚合物主链的折叠过程。聚合物主链能够保持其延伸的链状构象，导致只有蓝色形式的吸收带。
In the present study, a new diacetylene compound (PDATAZ), which readily forms a complementary hydrogen bonding self-assembly at the air-water interface or in the solid state with barbituric acid (BA) or cyanuric acid (CA), was designed and synthesized. The photopolymerization studies of PDATAZ and its assembly with BA or CA have revealed some important insights on the chromatic properties of polydiacetylenes. It was found that the chromatic property of polydiacetylenes is determined by whether the polymer chain is capable of adopting a linear chainlike shape. With the continuous increase of the length of the polymer chain, the original linear polyenyne backbone starts to "self-fold" to a "zigzag" structure due to the free rotation of single bonds within the polymer chain. The efficient pi-electron delocalization along the polyenyne backbone is interrupted by this process, leading to a chromatic change from the blue to red form of polydiacetylenes. If there are strong intermolecular interactions existing between the polar groups of the side chains, such as the complementary hydrogen bonding network between the triaminotriazine (TAZ) moiety of the diacetylene amphiphile and its complementary components, the movement of the side chains is restricted and the folding process of the polymer backbone is inhibited. The polymer backbone is able to maintain its extended chainlike conformation, leading to only the blue form absorption band.