title: A new type of charge-transfer salts based on tetrathiafulvalene-tetracarboxylate coordination polymers and methyl viologen.
abstract: Although charge-transfer compounds based on tetrathiafulvalene (TTF) derivatives have been intensively studied, {[cation](n+)·[TTFs](n-)} ion pair charge-transfer (IPCT) salts have not been reported. The aim of this research is to introduce functional organic cations, such as photoactive methyl viologen (MV(2+)), into the negatively charged TTF-metal coordination framework to obtain this new type of IPCT complex. X-ray structural analysis of the four compounds (MV)2[Li4(L)2(H2O)6] (1), {(MV)(L)[Na2(H2O)8]·4H2O}n (2), {(MV)[Mn(L)(H2O)2]·2H2O}n (3), and {(MV)[Mn(L)(H2O)2]}n (4), reveals that the electron donor (D) TTF moiety and the electron acceptor (A) MV(2+) form a regular mixed-stack arrangement in alternating DADA fashion. The TTF moiety and the MV(2+) cation are essentially parallel stacked to form the column structures. The strong electrostatic interaction is a main force to shorten the distance between the cation and anion planes. Optical diffuse-reflection spectra indicate that charge transfer occurs in these complexes. The ESR and magnetic measurements confirm that there is strong charge-transfer-induced partial electron transfer. Compounds 2, 3, and 4 show an effective and repeatable photocurrent response. The current intensities of 3 and 4 are higher than that of 2, which reflects that the coordination center of the Mn(II) ion has a great effect on the increasing photocurrent response.
authors.affiliation: College of Chemistry, Chemical Engineering and Materials Science, Soochow University , Suzhou 215123, People's Republic of China.
authors.forename: Yu-De
authors.initials: YD
authors.lastname: Huang
authors.forename: Peng
authors.initials: P
authors.lastname: Huo
authors.forename: Ming-Yan
authors.initials: MY
authors.lastname: Shao
authors.forename: Jing-Xue
authors.initials: JX
authors.lastname: Yin
authors.forename: Wei-Chun
authors.initials: WC
authors.lastname: Shen
authors.forename: Qin-Yu
authors.initials: QY
authors.lastname: Zhu
authors.forename: Jie
authors.initials: J
authors.lastname: Dai