Tuning of Stepwise Neutral–Ionic Transitions by Acceptor Site Doping in Alternating Donor/Acceptor Chains

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• 作者：Keita Nakabayashi ; Masaki Nishio ; Hitoshi Miyasaka
• 刊名：Inorganic Chemistry
• 出版年：2016
• 出版时间：March 7, 2016
• 年：2016
• 卷：55
• 期：5
• 页码：2473-2480
• 全文大小：602K
• ISSN：1520-510X

文摘

The stepwise neutral–ionic (N–I) phase transition found in the alternating donor/acceptor (DA) chain [Ru₂(2,3,5,6-F₄PhCO₂)₄(DMDCNQI)]·2(p-xylene) (0; 2,3,5,6-F₄PhCO₂^– = 2,3,5,6-tetrafluorobenzoate; DMDCNQI = 2,5-dimethyl-N,N′-dicyanoquinonediimine) was tuned by partly substituting the acceptor DMDCNQI with 2,5-dimethoxy-N,N′-dicyanoquinonediimine (DMeODCNQI), which displays a poorer electron affinity in an isostructural series. The site-doped series comprised [Ru₂(2,3,5,6-F₄PhCO₂)₄(DMDCNQI)_1–x(DMeODCNQI)_x]·2(p-xylene) for doping rates (x) = 0.05 (0.05-MeO), 0.10 (0.10-MeO), 0.15 (0.15-MeO), and 0.20 (0.20-MeO). The neutral chain [Ru₂(2,3,5,6-F₄PhCO₂)₄(DMeODCNQI)]·4(p-xylene) (1), which only contained DMeODCNQI, was also characterized. All site-doped compounds were isostructural to 0 except 1 despite their identical DA chain motif. Except at an x value of 0.20, they displayed a two-step N–I transition involving an intermediate phase. This transition occurred at high temperatures in 0 but shifted to lower temperatures in a parallel manner with increasing doping rate. Simultaneously, each transition broadened with increasing doping rate, leading to a convergence of two transitions at an x value approximating 0.2. Donor/acceptor-site-doping techniques present somewhat different impacts in terms of interchain Coulomb effects.