title: Effects of protonation and metal coordination on intramolecular charge transfer of tetrathiafulvalene compound.
abstract: A protonated bifunctional pyridine-based tetrathiafulvalene (TTF) derivative (DMT-TTF-pyH)NO3 and a copper(II) complex Cu(acac)2(DMT-TTF-py)2 have been obtained and studied. Electronic spectra of the protonated compound show a large ICT (intramolecular charge transfer) band shift (Deltalambda=136 nm) compared with that of the neutral compound. Cyclic voltammetry also shows a large shift of the redox potentials (DeltaE1/2(1)=77 mV). Theoretical calculation suggests that the pyridium substituent is a strong pi-electron acceptor. Crystal structures of the protonated compound and the metal complex have been obtained. The dihedral angle between least-squares planes of the pyridyl group and the dithiole ring might reflect the intensity of the ICT effect between the TTF moiety and the pyridyl group. It is also noteworthy that the TTF moiety could be oxidized to TTF2+ dication by Fe(ClO4)(3).6H2O when forming a metal complex, while the protonated TTF derivative can only be oxidized to the TTF*+ radical cation by Fe(ClO4)(3).6H2O even with an excess amount of the Fe(III) salt, which can be used to control the oxidation process to obtain neutral TTF, TTF*+ radical cation, or TTF2+ dication.
authors.affiliation: Department of Chemistry & Key Laboratory of Organic Synthesis of Jiangsu Province, Suzhou University, Suzhou 215123, P.R. China.
authors.forename: Qin-Yu
authors.initials: QY
authors.lastname: Zhu
authors.forename: Yu
authors.initials: Y
authors.lastname: Liu
authors.forename: Wen
authors.initials: W
authors.lastname: Lu
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Guo-Qing
authors.initials: GQ
authors.lastname: Bian
authors.forename: Gai-Yan
authors.initials: GY
authors.lastname: Niu
authors.forename: Jie
authors.initials: J
authors.lastname: Dai