Khan Inayat Ali, Gnezdilov Oleg I, Wang Yong-Lei, Filippov Andrei, Shah Faiz Ullah
Chemistry of Interfaces, Luleå University of Technology, SE-97187 Luleå, Sweden.
Institute of Physics, Kazan Federal University, 420008 Kazan, Russia.
J Phys Chem B. 2020 Dec 31;124(52):11962-11973. doi: 10.1021/acs.jpcb.0c08421. Epub 2020 Dec 21.
Ionic liquids (ILs) composed of tetra(-butyl)phosphonium [P] and tetra(-butyl)ammonium [N] cations paired with 2-furoate [FuA], tetrahydo-2-furoate [HFuA], and thiophene-2-carboxylate [TpA] anions are prepared to investigate the effects of electron delocalization in anion and the mutual interactions between cations and anions on their physical and electrochemical properties. The [P] cations-based ILs are found to be liquids, while the [N] cations-based ILs are semi-solids at room temperature. Thermogravimetric analysis revealed higher decomposition temperatures and differential scanning calorimetry analysis showed lower glass transition temperatures for phosphonium-based ILs than the ammonium-based counterparts. The ILs are arranged in the decreasing order of their ionic conductivities as [P][HFuA] (0.069 mS cm) > [P][FuA] (0.032 mS cm) > [P][TpA] (0.028 mS cm) at 20 °C. The oxidative limit of the ILs followed the sequence of [FuA]> [TpA]> [HFuA], as measured by linear sweep voltammetry. This order can be attributed to the electrons' delocalization in [FuA] and in [TpA] aromatic anions, which has enhanced the oxidative limit potentials and the overall electrochemical stabilities.
制备了由四（丁基）鏻[P]和四（丁基）铵[N]阳离子与2-呋喃甲酸盐[FuA]、四氢-2-呋喃甲酸盐[HFuA]和噻吩-2-羧酸盐[TpA]阴离子配对组成的离子液体（ILs），以研究阴离子中的电子离域以及阳离子与阴离子之间的相互作用对其物理和电化学性质的影响。发现基于[P]阳离子的离子液体在室温下为液体，而基于[N]阳离子的离子液体在室温下为半固体。热重分析表明，鏻基离子液体的分解温度较高，差示扫描量热分析表明，鏻基离子液体的玻璃化转变温度低于铵基离子液体。在20℃时，离子液体的离子电导率按以下顺序排列：[P][HFuA]（0.069 mS/cm）>[P][FuA]（0.032 mS/cm）>[P][TpA]（0.028 mS/cm）。通过线性扫描伏安法测量，离子液体的氧化极限遵循[FuA]>[TpA]>[HFuA]的顺序。这个顺序可以归因于[FuA]和[TpA]芳香族阴离子中的电子离域，这增强了氧化极限电位和整体电化学稳定性。
