Temporal behavior of the singlet molecular oxygen emission in imidazolium and morpholinium ionic liquids and its implications.
Temporal behavior of the singlet molecular oxygen emission in imidazolium and morpholinium ionic liquids and its implications.
复制标题
DOI：
10.1021/acs.jpcb.5b01996
复制
发表时间：
2015-05
期刊：
影响因子：
--
通讯作者：
Tsuyoshi Yoshida;A. Kawai;D. C. Khara;A. Samanta
中科院分区：
文献类型：
--
作者：
Tsuyoshi Yoshida;A. Kawai;D. C. Khara;A. Samanta
利用时间分辨近红外光谱研究了离子液体对单线态氧分子O2（（1）Δg）寿命的溶剂效应。在含有不同长度烷基链的吗啉离子液体和咪唑离子液体中，亚甲基蓝光敏化产生O2（（1）Δg）. O2（1）Δg →（3）Δ g（-）跃迁的发光时间曲线用单指数衰减函数表示。发现磷光寿命与吗啉离子液体的烷基链长度相关。通过考虑O2（（1）Δg）通过能量转移到吗啉阳离子中N-烷基链的高频C-H伸缩模式的有效猝灭来解释这一观察结果。有趣的是，我们发现O2（（1）Δg）猝灭的C-H伸缩模式的阳离子环显着抑制。根据离子液体的非均相结构，讨论了O2（（1）Δg）发射衰减过程的动力学.
The solvent effect of ionic liquids on the lifetime of singlet molecular oxygen, O2((1)Δg), was investigated by means of time-resolved near-IR emission spectroscopy. O2((1)Δg) was generated by photosensitization of methylene blue in morpholinium and imidazolium ionic liquids, both comprising various alkyl chains of different lengths. The measured time profiles of O2((1)Δg) luminescence for the (1)Δg → (3)Σg(-) transition were represented by a single-exponential decay function. The phosphorescence lifetime was found to be correlated with the alkyl chain length of the morpholinium ionic liquids. This observation was interpreted by considering efficient quenching of O2((1)Δg) through energy transfer to the high-frequency C-H stretching modes of the N-alkyl chain in the morpholinium cation. Interestingly, we found that O2((1)Δg) quenching by the C-H stretching modes of the ring of the cations was remarkably depressed. The kinetics of the O2((1)Δg) emission decay process was discussed on the basis of the heterogeneous structure of ionic liquids consisting of polar and nonpolar domains.