Takamuku Toshiyuki, Nishiyama Daiki, Kawano Masahiro, Miannay François-Alexandre, Idrissi Abdenacer
Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Honjo-machi, Saga 840-8502, Japan.
Functional Biomolecular Science, Graduate School of Advanced Health Sciences, Saga University, Honjo-machi, Saga 840-8502, Japan.
Phys Chem Chem Phys. 2023 Apr 5;25(14):9868-9880. doi: 10.1039/d2cp05858h.
In order to determine the self-diffusion coefficients of all the species in the solutions at 298.2 K, H and F NMR diffusion ordered spectroscopy (DOSY) has been conducted on coumarin 153 (C153) in binary mixed solvents of an imidazolium-based ionic liquid (IL), 1-dodecyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide (CmimTFSA), with three molecular liquids (MLs) of chloroform (CL), benzene (BZ), and propylene carbonate (PC) as a function of ML mole fraction . Below ≈ 0.8, the values of each species do not significantly depend on the MLs. However, above this mole fraction, the diffusion of C153 becomes smoother in the order of BZ ≈ CL > PC systems. The interactions among C153, Cmim, TFSA, and ML molecules have been investigated using infrared (IR) and H and C NMR spectroscopic techniques. The relations of the diffusion of the species with the interactions among them have been discussed on the molecular scale. In the IL solution, the C153 carbonyl oxygen atom is hydrogen-bonded with the imidazolium ring C-H atom of Cmim. Cmim also forms an ion pair with TFSA. Thus, C153, Cmim, and TFSA cooperatively move in the CL and BZ solutions at a lower ML content, < ∼0.8. On the other hand, at a higher ML content, > ∼0.8, the C153 molecule diffuses with CL and BZ molecules because of the hydrogen bonding between the C153 carbonyl O atom and the CL H atom and the π-π interaction between the C153 and BZ ring planes, respectively. For the PC system, the change in the relative self-diffusion coefficients of each species with increasing differs from those for the CL and BZ systems because of both hydrogen bonding donor H and acceptor O atoms of PC for C153, the IL cation and anion, and PC themselves.
为了测定298.2 K时溶液中所有物种的自扩散系数，在基于咪唑鎓的离子液体（IL）1-十二烷基-3-甲基咪唑双（三氟甲基磺酰）酰胺（CmimTFSA）与三种分子液体（ML）氯仿（CL）、苯（BZ）和碳酸丙烯酯（PC）的二元混合溶剂中，对香豆素153（C153）进行了氢和氟核磁共振扩散有序光谱（DOSY）实验，实验结果作为ML摩尔分数的函数。在≈0.8以下，各物种的值对MLs没有显著依赖性。然而，高于该摩尔分数时，C153的扩散在BZ≈CL>PC体系中变得更平滑。利用红外（IR）以及氢和碳核磁共振光谱技术研究了C153、Cmim、TFSA和ML分子之间的相互作用。在分子尺度上讨论了物种扩散与它们之间相互作用的关系。在IL溶液中，C153羰基氧原子与Cmim的咪唑环C-H原子形成氢键。Cmim还与TFSA形成离子对。因此，在较低的ML含量（<∼0.8）下，C153、Cmim和TFSA在CL和BZ溶液中协同移动。另一方面，在较高的ML含量（>∼0.8）下，由于C153羰基O原子与CL H原子之间的氢键以及C153与BZ环平面之间的π-π相互作用，C153分子分别与CL和BZ分子一起扩散。对于PC体系，由于PC对C153、IL阳离子和阴离子以及PC自身都有氢键供体H和受体O原子，各物种相对自扩散系数随增加的变化与CL和BZ体系不同。
