Influence of chiral ionic liquids on stereoselective fluorescence quenching by photoinduced electron transfer in a naproxen dyad.
Influence of chiral ionic liquids on stereoselective fluorescence quenching by photoinduced electron transfer in a naproxen dyad.
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DOI：
10.1021/jp904311b
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发表时间：
2009-07
期刊：
影响因子：
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通讯作者：
S. Bose;A. Wijeratne;A. Thite;G. Kraus;D. Armstrong;J. Petrich
中科院分区：
文献类型：
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作者：
S. Bose;A. Wijeratne;A. Thite;G. Kraus;D. Armstrong;J. Petrich
在一对N-甲基咪唑甲基薄荷醚-NTf（2）手性离子液体中的萘普生二联体的先前研究中（J. Phys. Chem. B 2008，112，7555），我们观察到尽管分子内电子转移受阻，但在二联体的荧光寿命中获得一致的小立体差异。我们提出，这种歧视是纯粹的电子性质，并没有产生几何效应，这可能会影响非辐射速率过程，如分子内电子转移。在我们目前的工作中，我们已经研究了相同的手性萘普生二联体分子在先前研究的薄荷基NTf（2）离子液体和双（四丁基鏻）（TBP）d-，l-酒石酸盐离子液体中的相互作用。与基于薄荷基的IL对不同，双（TBP）酒石酸盐对映体液体中的淬灭量不同，酒石酸盐对映体对二价体的非辐射速率具有不同的温度依赖性。这种手性区别很可能是由于手性分子不同构象的空间效应。我们已经表明，溶剂的粘度和极性可以影响电子转移的速率。另一方面，在基于薄荷基的NTf（2）IL溶剂中没有观察到这样的电子转移猝灭。据我们所知，这是手性离子液体通过光诱导的分子内电子转移诱导立体选择性荧光猝灭的第一个例子。
In a previous study of a naproxen dyad in a pair of N-methylimidazoliummethyl menthylether-NTf(2) chiral ionic liquids (J. Phys. Chem. B 2008, 112, 7555), we observed that though intramolecular electron transfer was impeded, a consistent small stereodifferentiation in the fluorescence lifetime of the dyad was obtained. We proposed that this discrimination was purely electronic in nature and did not arise from geometrical effects, which can influence nonradiative rate processes, such as intramolecular electron transfer. In our present work, we have studied the interaction of the same chiral naproxen dyad molecule in both the previously studied menthyl-based NTf(2) ionic liquids and also in bis(tertrabutylphosphonium) (TBP) d-,l-tartrate ionic liquids. Unlike in the menthyl-based IL pair, the amount of quenching is different in the bis(TBP) tartrate enantiomeric liquids and the tartrate enantiomers have a different temperature dependence on the nonradiative rate of the dyad. This chiral discrimination most likely arises from the steric effects of the different conformations of the chiral molecules. We have shown that the viscosity and polarity of the solvents can influence the rate of electron transfer. On the other hand, no such electron transfer quenching is observed in the menthyl-based NTf(2) IL solvents. To our knowledge, this is the first example of chiral ionic liquids inducing a stereoselective fluorescence quenching by photoinduced, intramolecular electron transfer.