We have investigated the kinetic and thermodynamic parameters of thermal reversion of the spirooxazine 1,3,3-trimethyl-5â²-(2-benzothiazolyl)-spiroindoline-2,3â²-naphtho(2,1-b)(1,4) oxazine (SO) in molecular solvents and ionic liquids containing the [NTf2]â anion. ET(30) and KamletâTaft parameter studies were employed to interpret IL polarity and attempt to rationalise the kineticâpolarity relationship of MCâSO relaxation. The observed thermal relaxation of SO within ionic liquids was slower than that of molecular solvents with similar polarity, indicating a greater degree of interactions between the ionic liquid ions and the zwitterionic MC isomer, which led to increased lifetimes for the MCâion complexes (19.6 s in acetonitrile and 90.9 s in [P6,6,6,14][NTf2]). Thermodynamic parameters of activation implied enhanced ordering of SO in ILs and its subsequent effect on thermal reversion of SO. Activation parameters found MCâSO relaxation was more temperature dependent in polar protic ILs such as [bmIm]+ than aprotic ILs such as [P6,6,6,14][NTf2] with ÎSâ¡ values of 40 J K molâ1 and â8.6 J K molâ1, respectively. Activation energies were generally higher in ILs (83.9â97 kJ molâ1) compared to molecular solvents (67.8â89.8 kJ molâ1), which was reflected in longer lifetimes of MC due to greater energy barriers of relaxation to SO. Pre-metathesis cleaning of precursor salts was found to be necessary in order to obtain spectroscopic grade ILs for physicochemical analysis using solvatochromic probe dyes. Inconsistencies in the polarityâkinetic relationship further reinforced the belief that measuring polarity of ILs may not be possible with solvatochromic probe dyes.
我们研究了螺恶嗪 1,3,3-trimethyl-5â²-(2-
苯并噻唑基)-spiroindoline-2,3â²-naphtho(2,1-b)(1 的热回复动力学和热力学参数,4) 含有[NTf2]-阴离子的分子溶剂和
离子液体中的恶嗪(SO)。 ET(30) 和 Kamlet–Taft 参数研究被用来解释 IL 极性,并试图合理化 MC–SO 弛豫的动力学–极性关系。观察到的
离子液体中 SO 的热弛豫速度比具有相似极性的分子溶剂慢,这表明
离子液体离子和两性离子 MC 异构体之间的相互作用程度更大,这导致 MC-离子配合物的寿命增加(
乙腈中为 19.6 秒,[P6,6,6,14][NTf2] 中为 90.9 秒。活化的热力学参数意味着
离子液体中 SO 的有序性增强及其对 SO 热回复的后续影响。激活参数发现,极性质子
离子液体(例如 [bmIm]+)中的 MC–SO 弛豫比非质子
离子液体(例如 [P6,6,6,14][NTf2])中的温度依赖性更强,其中 αS– 值为 40 J K molâ分别为≤1 和≤8.6 J K mol≤1。与分子溶剂 (67.8–89.8 kJ mol–1) 相比,
离子液体 (83.9–97 kJ mol–1) 的活化能普遍较高,这反映在由于 MC 的能垒更大而具有更长的寿命。放松到如此。研究发现,为了获得用于使用溶剂化显色探针
染料进行物理
化学分析的光谱级
离子液体,需要对前体盐进行预复分解清洗。极性与动力学关系的不一致进一步强化了这样的信念:使用溶剂化显色探针
染料可能无法测量
离子液体的极性。