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白玉浴血木虫 (正式写手)
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[求助]
请问这一段中，到底是怎么解释了探针分子的移动的？
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For comprehending the solvation dynamics process, a thorough understanding of the micellar structure and location of the probe within the micelle is necessary. The dielectric constant is an important tool for measuring the polarity of a solvent, which changes from bulk solvent to micellar solution with the probe in the palisade layer.72 According to the molecular approach for the solvation relaxation process, which takes into account the solvent structures around the probe, it appears to be more logical to understand the results in micellar media, although it is more complicated than the homogeneous solution. Inside the micellar palisade layer, the movement of the water molecules is much more hindered than the bulk water molecules, hence it is expected that the solvation process inside the micelle should be slower than that in the bulk. The water molecules adjacent to the probe are much more restricted and difficult to rearrange than the water molecules somewhat away from the probe. So the slower solvation component arises from the response of the few restricted water molecules that are adjacent to the probe, and the collective response of the relatively large number of water molecules that are not in the vicinity of the probe gives rise to the faster solvation component.75 From UV−visible spectra, fluorescence spectra, and also anisotropy values, one can conclude that the probe molecules reside inside the palisade layer of the micelles. The average solvation time of C- 343 at 298 K in aqueous solution of 28 mM SB-16 was found to be 2.02 ns (Table 3), with components 0.64 ns (80%) and 7.57 ns (20%). The process becomes faster in the presence of both the surfactant (SDS) and the RTIL (EmimOs), and the effect is more pronounced in the case of SDS. With the addition of 10 mM EmimOs and SDS to 28 mM SB-16 solution, the average solvation time changes from 2.02 to 1.36 and 1.00 ns, respectively. The slow component of the solvation time of C- 343 at 298 K in 28 mM SB-16 solution was found to be 7.57 ns with amplitude of 20%. With addition of 10 mM EmimOs, this value decreases from 7.57 to 3.23 ns and the amplitude changes from 20% to 33%, which clearly indicates that the strength of the hydrogen bonding decreases but the water penetration increases. On addition of 10 mM SDS to the 28 mM SB-16 solution, the slow component decreases from 7.57 to 1.19 ns and the amplitude increases from 20% to 76% which suggests that the strength of hydrogen bonding decreases while the water penetration increases abnormally. This is a manifestation of the movement of the probe molecules to the bulk water phase. Now, considering the fast component of the solvation dynamics, the addition of 10 mM EmimOs to a 28 mM SB-16 solution it changes from 0.64 to 0.44 ns and the magnitudedecreases from 80% to 67%. This change is clearly a manifestation of the movement of the probe molecules from the micellar palisade layer to the bulk solvent. The effect of addition of 10 mM SDS to a 28 mM SB-16 solution is more drastic since the fast component then changes to 0.40 ns with a magnitude of 24%. To see the effect of the −OH moiety, we performed a similar study with the addition of 10 mM DAH, as a protic IL. In that case, the average solvation time decreased from 2.02 to 1.75 ns, suggesting that the effect of DAH is similar compare to those for EmimOs and SDS, although the effect is much less compared to those for SDS and EmimOs. As a result, we can say that the efficiency of the movement of the probe solely depends on the chain length and follows the order SDS > EminOs > DAH, becasue SDS possesses a dedecyl chain, EmimOs, possesses an octyl chain, and DAH possesses a hexanoate chain. |
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