Huang Xin, Jiang Siguang, Liu Minghua
CAS Key Laboratory of Colloid and Interface Science, Institute of Chemistry, The Chinese Academy of Sciences, 100080, Beijing, People's Republic of China.
J Phys Chem B. 2005 Jan 13;109(1):114-9. doi: 10.1021/jp046500m.
Some novel properties of organized molecular films of 10,12-tricosadiynoic acid (TDA), which were modulated by transition metal ions, were investigated. It was found that metal ions such as Cu(2+), Zn(2+), Ni(2+), Cd(2+), and Ag(+) in the subphase can greatly affect the monolayer formation of TDA and the properties of the subsequently deposited Langmuir-Blodgett (LB) films, particularly in the case of Ag(+), Zn(2+), and Cu(2+) ions. TDA LB film from the subphase containing Ag(+) ion could not be photopolymerized. It was suggested that both the strong chelating property to the carboxylate and the easy reduction of Ag(+) in the film disrupted the topochemical sequence of TDA and resulted in no polymerization in the film. Zinc ion coordinated TDA film could be photopolymerized into a blue polydiacetylene (PDA) film, which showed a reversible thermochromism between blue and purple color upon thermal stimulation. Fourier transform infrared spectra revealed the difference of the Zn(2+)-PDA film from those of the other ions, and the mechanism of the thermochromism was discussed. Copper ion coordinated TDA film could only be photopolymerized to a red PDA film, which showed supramolecular chirality although TDA itself was achiral. Atomic force microscopic measurements revealed the nanofiber structure in the Cu(2+)-PDA film. The supramolecular chirality of the Cu(2+)-PDA film was suggested to be due to the arrangement of the polymer backbone in a helical sense. Furthermore, it was found that the chiral assemblies from the achiral TDA molecules were very stable and the chirality could be kept even upon heating or treating with alkaline solution. While many synthetic efforts have been devoted to the functionalization of PDA films, we provided a simple method of modulating the organization and function of PDA films through metal ions.
研究了10,12-二十三碳二炔酸（TDA）有序分子膜的一些新特性，这些特性受到过渡金属离子的调控。研究发现，亚相中诸如Cu(2+)、Zn(2+)、Ni(2+)、Cd(2+)和Ag(+)等金属离子会极大地影响TDA的单分子层形成以及随后沉积的朗缪尔-布洛杰特（LB）膜的性质，特别是在Ag(+)、Zn(2+)和Cu(2+)离子的情况下。来自含有Ag(+)离子亚相的TDA LB膜无法进行光聚合。研究表明，Ag(+)对羧酸盐的强螯合性质以及膜中Ag(+)的易于还原破坏了TDA的拓扑化学序列，导致膜中无法聚合。锌离子配位的TDA膜可以光聚合成蓝色聚二乙炔（PDA）膜，该膜在热刺激下呈现蓝色和紫色之间的可逆热致变色现象。傅里叶变换红外光谱揭示了Zn(2+)-PDA膜与其他离子的膜之间的差异，并讨论了热致变色的机理。铜离子配位的TDA膜只能光聚合成红色PDA膜，尽管TDA本身是无手性的，但该膜表现出超分子手性。原子力显微镜测量揭示了Cu(2+)-PDA膜中的纳米纤维结构。Cu(2+)-PDA膜的超分子手性被认为是由于聚合物主链呈螺旋状排列。此外，研究发现由无手性TDA分子形成的手性组装体非常稳定，即使在加热或用碱性溶液处理后手性仍可保持。虽然已经进行了许多合成努力来实现PDA膜的功能化，但我们提供了一种通过金属离子调节PDA膜的组装和功能的简单方法。
