Abstract
A dual probe was investigated by UV-Vis, fluorescence, and ESR
spectroscopy. It comprises the pyrene chromophore and the paramagnetic
2,2,6,6-tetramethylpiperidinyl-N-oxyl radical that are covalently
linked together via an ester bridge. The dual probe was used to
investigate molecular solvents of different polarity as well as ionic
liquids bearing either imidazolium or pyrrolidinium cations and
various anions, such as bis(trifluoromethylsulfonyl)imide,
tetrafluoroborate, tris(pentafluoroethyl)trifluorophosphate, or
dicyanamide. The dual probe does not show solvatochromism that is
typical for some pyrenes. Furthermore, the dual probe is considerable
less mobile compared to 2,2,6,6-tetramethylpiperidinyl-N-oxyl
(TEMPO) without additional substituent as detected by ESR
spectroscopy. This is caused by the bulky pyrenyl substituent bound at
the dual probe resulting in a reduced mobility of the dual probe.
摘要 通过UV-Vis、荧光和ESR光谱学研究了一种双探针。它由芘色团和顺磁性的2,2,6,6-四甲基哌啶-N-氧自由基通过酯桥连接而成。该双探针用于研究不同极性的分子溶剂以及带有咪唑或吡咯烷基阳离子和各种阴离子的离子液体,例如双(三氟甲基磺酰)亚胺、四氟硼酸盐、三(全氟乙基)三氟磷酸盐或二氰胺。该双探针不显示一些芘类化合物典型的溶剂致色性。此外,通过ESR光谱学检测,与没有额外取代基的2,2,6,6-四甲基哌啶-N-氧自由基(TEMPO)相比,该双探针的移动性较差。这是由于双探针上的笨重芘基团结合导致双探针的移动性降低。