Yusuke Baba, Ryo Tsunashima*, Norihisa Hoshino, Tomoyuki Akutagawa, Shin-Ichiro Noro and Takayoshi Nakamura Pages 8 - 12 ( 5 )
Background: Polyoxometalate (POM) clusters are molecular metal-oxide that possess advantages in integrating functionalities at the molecular level. Redox activity is key characteristic of the POMs where the electron-withdrawing ability is changed according to environments that surroundings POMs. Achieving switching phenomena of electronic state of POMs are of great interest for various applications.
Objective: It is of fundamental interest to develop switching of electronic state of POMs by outer stimulus. For this purpose, we investigate the solvent effect to electron-withdrawing ability of POM so as to coupling with macroscopic electric property of the POM based salts.
Method: We have developed these characteristics of POMs to design CT system by hybridizing with pyridyl-tetrathiafulvalene (TTFPy) molecule. TTFPy was reacted with Ni(II) and [α-SiW12O40]4-, yielding a single crystal with composition of [NiII(DMSO)5(TTFPy)]2[α-SiW12O40] (1). And we have revealed that a single crystal of the compound turns crystal color from orange (1) to black (1') by immersing crystals in methanol. In this paper, we newly analyses a structure of the single crystal 1 by X-ray diffraction analysis in addition to investigation of this chemo-chromic characteristics using varieties of organic solvent.
Results: It was revealed that solvent acceptor number was important to consider the chromic in which transition from 1 to 1' was induced with organic solvents whose acceptor number was larger than 18. In addition, electrical properties of both crystals and revealed that conductivity was increased in 1'.
Conclusion: Our results show that solvent-induced chemo-chromic characteristics were triggered by immersing crystals in a solvent. Other chemo-chromic characteristics will be explored by surrounding crystal in more ion rich environment tuned by Li+ ions toward electrode materials for Li ion batteries, for example. In addition, our findings reported here emphasize interest and importance of POM-based hybrid in which grand state is not in CT state.
Polyoxometalate, ttf, charge transfer, electrical conduction, transition, chromic characteristics.
Graduate School of Science and Engineering, Yamaguchi University, Yamaguchi, 753 8512, Graduate School of Science and Engineering, Yamaguchi University, Yamaguchi, 753 8512, Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Sendai 980-8577, Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Sendai 980-8577, Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0020, Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0020