Metal-Promoted Intermolecular Electron Transfer in Tetrathiafulvalene–Thiacalixarene Conjugates and Tetrachlorobenzoquinone
journal contributionposted on 16.01.2015, 00:00 by Bang-Tun Zhao, Qi-Ming Peng, Xiao-Min Zhu, Zhen-Ning Yan, Wei-Min Zhu
In this work, two series of tetrathiafulvalene (TTF) and thiacalixarene (TCA) conjugates (TTF–TCA) were designed by CuAAC click reactions. The results obtained from NMR and 1H NMR NOE indicated that their conformations of thiacalixarene framework may prefer to 1,3-alternate. The cyclic voltammograms of four TTF–TCA compounds containing electroactive TTF units were provided. Meanwhile, their intermolecular electron-transfer (ET) behaviors with tetrachlorobenzoquinone (Q) mediated by different metal ions, Sc3+, Pb2+, Ag+, Cd2+, and Zn2+, in CH3CN–CH2Cl2 (V/V = 1:1) solution were studied and analyzed via UV–vis spectroscopy. It was determined that intermolecular ET between each TTF–TCA and Q ensemble was not observed without introduction of the metal ions mentioned above. The added specified metal ions most likely induced the intermolecular ET between TTF–TCA and Q ensemble, and the effects of Sc3+ functions were the most imperative. The intermolecular ET also proved to be reliant on the structure of TTF–TCA, where TTF–TCA 7a and 7b were more effective than TTF–TCA 6a and 6b. The difference may be credited to TTF–TCA 7a or 7b possessing two independent TTF pendants and providing a more synergic coordination among the TTF radical cation and Q radical anion with a metal ion.