Protic Ionic Liquids for the Belousov-Zhabotinsky Reaction: Aspects of the BZ Reaction in Protic Ionic Liquids and Its Use for the Autonomous Coil-Globule Oscillation of a Linear Polymer
Protic Ionic Liquids for the Belousov-Zhabotinsky Reaction: Aspects of the BZ Reaction in Protic Ionic Liquids and Its Use for the Autonomous Coil-Globule Oscillation of a Linear Polymer
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用于 Belousov-Zhabotinsky 反应的质子离子液体：质子离子液体中 BZ 反应的方面及其在线性聚合物自主线圈球振荡中的应用
DOI：
10.1021/acs.jpcb.7b01309
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发表时间：
2017
期刊：
影响因子：
3.3
通讯作者：
Ryo Yoshida
中科院分区：
文献类型：
--
作者：
Takeshi Ueki;Ko Matsukawa;Tsukuru Masuda;Ryo Yoshida
在此，我们描述的Belousov-Zhabotinsky（BZ）反应的物理化学方面的水合质子离子液体（PIL）结合不同的阳离子与硫酸氢根（[HSO 4-]）阴离子。通过硫酸与13种脂肪胺的中和反应制备了PIL。选择胺结构来研究活性质子数、烷基链长度（亲水性）和阳离子线性度对BZ反应机理的影响。PIL的pKa值（pKa= 1.0-2.5）显著高于BZ反应中常规质子源无机酸（H2SO 4 = −3.0; HNO 3 = −1.4）的pKa值。当适量的BZ反应底物（NaBrO 3氧化剂、丙二酸还原剂）加入到水合PIL中时，Ru（bpy）3发生周期性氧化还原振荡。当采用亲水性阳离子（铵、乙基铵和二甲基乙基铵）时，实现了持久的BZ振荡。有趣的是，对于在其阳离子结构中具有少于4个碳原子的PIL，实现了大的ΔA5000（从BZ反应开始5000 s后观察到的振荡稳定性尺度的吸光度的振荡幅度）。在水合PIL中的表观BZ振荡活化能（Ea）被估计为约40 kJ mol-1，这比在常规系统中观察到的小30 kJ mol-1。BZ反应子过程中的催化反应抑制了反应的总活化能。为了实现持久的自振荡聚合物材料在温和的条件下起作用，我们展示了一个自主的线圈-小球聚合物链转变（BZ驱动），直接将化学能转化为机械运动在水合PIL中没有自由扩散Ru（bpy）3金属催化剂。选择乙基硫酸氢铵（[ea-H+][HSO 4-]）作为BZ反应的合适质子源。通过原子转移自由基聚合（ATRP）和金属催化剂的后修饰，成功地制备了一种结构明确的自振荡聚合物，该聚合物将Ru（bpy）3金属催化剂引入到聚合物主链中，并与水合[ea-H+][HSO 4-]具有良好的相容性。通过与PILs的结合，聚合物在温和条件下的溶解度的节律性变化将扩大PILs在新型功能材料中的潜在应用。
Herein, we describe the physicochemical aspects of the Belousov–Zhabotinsky (BZ) reaction in hydrated protic ionic liquids (PILs) combined with different cations with a hydrogen sulfate ([HSO4–]) anion. PILs were prepared from the neutralization reactions of sulfuric acid with 13 different aliphatic amines. The amine structure was selected to investigate the effect of the number of active protons, alkyl chain length (hydrophilicity), and cationic linearity on the mechanism of the BZ reaction. The pKavalues of PILs were significantly higher (pKa= 1.0–2.5) than those of inorganic acids (H2SO4= −3.0; HNO3= −1.4), the conventional proton source in a BZ reaction. A periodic redox oscillation was observed in Ru(bpy)3when appropriate amounts of BZ reaction substrates (NaBrO3oxidant; malonic acid reductant) were added to the hydrated PILs. A long-lasting BZ oscillation was realized when hydrophilic cations (ammonium, ethylammonium, and dimethylethylammonium) were employed. Interestingly, a large ΔA5000(oscillation amplitude of absorbance for the scale of the oscillation stability observed after 5000 s from the initiation of the BZ reaction) was achieved for PILs possessing less than four carbon atoms in their cationic structure. The apparent BZ oscillation activation energy (Ea) in the hydrated PILs was estimated to be ∼40 kJ mol–1, which is 30 kJ mol–1less than that observed in a conventional system. The catalytic reaction in the BZ reaction subprocess suppresses the total activation energy of the reaction. To realize long-lasting self-oscillating polymeric materials acting under milder condition, we demonstrated an autonomous coil–globule polymer chain transition (BZ-driven) that directly converts chemical energy to mechanical motion in hydrated PILs without freely diffusing Ru(bpy)3metal catalyst. Ethylammonium hydrogen sulfate ([ea-H+][HSO4–]) is selected as the suitable proton source for the BZ reaction. A well-defined self-oscillating polymer that incorporated Ru(bpy)3metal catalyst into the polymer backbone accompanied by good compatibility in hydrated [ea-H+][HSO4–] is successfully prepared by ATRP, followed by postmodification of the metal catalyst. The rhythmic solubility changes of the polymer under milder conditions, realized by combination with PILs, will expand the potential applications of PILs to novel functional materials.