Zhang Yun-Chang, Qin Ying, Wang Hui, Zhang Dan-Wei, Yang Guanyu, Li Zhan-Ting
Department of Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Fudan University, 220 Handan Road, Shanghai, 200433, China.
College of Chemistry and Molecular Engineering, Zhengzhou University, 100 Kexue Street, Zhengzhou, 450001, China.
Chem Asian J. 2016 Apr 5;11(7):1065-70. doi: 10.1002/asia.201600017. Epub 2016 Feb 23.
Two water-soluble para-xylylene-connected 4,4'-bipyridinium (BIPY(2+) ) polymers have been prepared. UV-Vis absorption, (1) H NMR spectroscopy, and cyclic voltammetry experiments support that in water the BIPY(2+) units in the polymers form stable 1:1 charge-transfer complexes with tetrathiafulvalene (TTF) guests that bear two or four carboxylate groups. These charge-transfer complexes are stabilized by the donor-acceptor interaction between electron-rich TTF and electron-deficient BIPY(2+) units and electrostatic attraction between the dicationic BIPY(2+) units and the anionic carboxylate groups attached to the TTF core. On the basis of UV-Vis experiments, a lower limit to the apparent association constant of the TTF⋅BIPY(2+) complexes of the mixtures, 1.8×10(6) m(-1) , has been estimated in water. Control experiments reveal substantially reduced binding ability of the neutral TTF di- and tetracarboxylic acids to the BIPY(2+) molecules and polymers. Moreover, the stability of the charge-transfer complexes formed by the BIPY(2+) units of the polymers are considerably higher than that of the complexes formed between two monomeric BIPY(2+) controls and the dicarboxylate-TTF donor; this has been attributed to the mutually strengthened electron-deficient nature of the BIPY(2+) units of the polymers due to the electron-withdrawing effect of the BIPY(2+) units.
已制备出两种水溶性对二甲苯连接的4,4'-联吡啶鎓（BIPY(2+) ）聚合物。紫外-可见吸收光谱、(1)H 核磁共振光谱和循环伏安实验表明，在水中聚合物中的BIPY(2+) 单元与带有两个或四个羧酸根基团的四硫富瓦烯（TTF）客体形成稳定的1:1电荷转移络合物。这些电荷转移络合物通过富电子的TTF与缺电子的BIPY(2+) 单元之间的供体-受体相互作用以及二价阳离子BIPY(2+) 单元与连接在TTF核上的阴离子羧酸根基团之间的静电吸引得以稳定。基于紫外-可见实验，已估计出混合物中TTF⋅BIPY(2+) 络合物的表观缔合常数下限为1.8×10(6) m(-1) 。对照实验表明中性TTF二元羧酸和四元羧酸与BIPY(2+) 分子及聚合物的结合能力大幅降低。此外，聚合物中BIPY(2+) 单元形成的电荷转移络合物的稳定性明显高于两个单体BIPY(2+) 对照物与二羧酸-TTF供体形成的络合物；这归因于聚合物中BIPY(2+) 单元由于其吸电子效应而相互增强的缺电子性质。
