Institute of Chemistry, University of Silesia in Katowice, Szkolna 9, 40-006 Katowice, Poland.
August Chełkowski Institute of Physics, University of Silesia in Katowice, 75 Pulku Piechoty 1, 41-500 Chorzow, Poland.
J Phys Chem B. 2021 Mar 25;125(11):2960-2967. doi: 10.1021/acs.jpcb.0c10970. Epub 2021 Mar 11.
Herein, we investigated the molecular dynamics as well as intramolecular interactions in two primary monohydroxy alcohols (MA), 2-ethyl-1-hexanol (2EHOH) and -butanol (BOH), by means of broad-band dielectric (BDS) and Fourier transform infrared (FTIR) spectroscopy. The modeling data obtained from dielectric studies within the Rubinstein approach [ 2013, 46, 7525-7541] originally developed to describe the dynamical properties of self-assembling macromolecules allowed us to calculate the energy barrier () of dissociation from the temperature dependences of relaxation times of Debye and structural processes. We found ∼ 19.4 ± 0.8 and 5.3 ± 0.4 kJ/mol for the former and latter systems, respectively. On the other hand, FTIR data analyzed within the van't Hoff relationship yielded the energy barriers for dissociation ∼ 20.3 ± 2.1 and 12.4 ± 1.6 kJ/mol for 2EHOH and BOH, respectively. Hence, there was almost a perfect agreement between the values of estimated from dielectric and FTIR studies for the 2EHOH, while some notable discrepancy was noted for the second alcohol. A quite significant difference in the activation barrier of dissociation indicates that there are probably supramolecular clusters of varying geometry or a ring-chain-like equilibrium is strongly affected in both alcohols. Nevertheless, our analysis showed that the association/dissociation processes undergoing within nanoassociates are one of the main factors underlying the molecular origin of the Debye process, supporting the transient chain model.
在这里，我们通过宽频介电 (BDS) 和傅里叶变换红外 (FTIR) 光谱研究了两种主要的单羟基醇 (MA)，即 2-乙基-1-己醇 (2EHOH) 和 -丁醇 (BOH) 的分子动力学以及分子内相互作用。通过 Rubinstein 方法 [2013, 46, 7525-7541] 获得的介电研究模型数据，该方法最初用于描述自组装大分子的动力学性质，使我们能够从德拜弛豫时间和结构过程的温度依赖性计算解离的能量势垒 ()。我们发现前者和后者的系统分别为 ∼19.4 ± 0.8 和 5.3 ± 0.4 kJ/mol。另一方面，在范特霍夫关系内分析的 FTIR 数据得出的解离能垒分别为 2EHOH 和 BOH 的 ∼20.3 ± 2.1 和 12.4 ± 1.6 kJ/mol。因此，从介电和 FTIR 研究中估计的 值之间几乎完全一致对于 2EHOH，而对于第二种醇则存在一些明显的差异。解离的活化势垒的相当大差异表明，在这两种醇中，可能存在具有不同几何形状的超分子簇，或者环链样平衡受到强烈影响。然而，我们的分析表明，在纳米缔合物内进行的缔合/解离过程是德拜过程分子起源的主要因素之一，支持瞬态链模型。
