title: Bipyridinium Polymers That Dock Tetrathiafulvalene Guests in Water Driven by Donor-Acceptor and Ion Pair Interactions.
abstract: 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.
authors.affiliation: Department of Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Fudan University, 220 Handan Road, Shanghai, 200433, China.
authors.forename: Yun-Chang
authors.initials: YC
authors.lastname: Zhang
authors.affiliation: College of Chemistry and Molecular Engineering, Zhengzhou University, 100 Kexue Street, Zhengzhou, 450001, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Qin
authors.affiliation: Department of Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Fudan University, 220 Handan Road, Shanghai, 200433, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Fudan University, 220 Handan Road, Shanghai, 200433, China. zhangdw@fudan.edu.cn.
authors.forename: Dan-Wei
authors.initials: DW
authors.lastname: Zhang
authors.affiliation: College of Chemistry and Molecular Engineering, Zhengzhou University, 100 Kexue Street, Zhengzhou, 450001, China. yangguanyu@zzu.edu.cn.
authors.forename: Guanyu
authors.initials: G
authors.lastname: Yang
authors.affiliation: Department of Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Fudan University, 220 Handan Road, Shanghai, 200433, China. ztli@fudan.edu.cn.
authors.forename: Zhan-Ting
authors.initials: ZT
authors.lastname: Li
keywords: bipyridinium; donor-acceptor interactions; electrostatic attractions; polymers; tetrathiafulvalene