Attri Pankaj, Baik Ku Youn, Venkatesu Pannuru, Kim In Tae, Choi Eun Ha
Plasma Bioscience Research Center/Department of Electrical and Biological Physics, Kwangwoon University, Seoul, Korea.
Department of Chemistry, University of Delhi, Delhi, India.
PLoS One. 2014 Jan 29;9(1):e86530. doi: 10.1371/journal.pone.0086530. eCollection 2014.
In this work, we have explored the thermophysical properties of tetraalkylammonium hydroxide ionic liquids (ILs) such as tetrapropylammonium hydroxide (TPAH) and tetrabutylammonium hydroxide (TBAH) with isomers of butanol (1-butanol, 2-butanol and 2-methyl-2-propanol) within the temperature range 293.15-313.15 K, with interval of 5 K and over the varied concentration range of ILs. The molecular interactions between ILs and butanol isomers are essential for understanding the function of ILs in related measures and excess functions are sensitive probe for the molecular interactions. Therefore, we calculated the excess molar volume (V(E) ) and the deviation in isentropic compressibility (Δκs ) using the experimental values such as densities (ρ) and ultrasonic sound velocities (u) that are measured over the whole compositions range at five different temperatures (293.15, 298.15, 303.15, 308.15 and 313.15 K) and atmospheric pressure. These excess functions were adequately correlated by using the Redlich-Kister polynomial equation. It was observed that for all studied systems, the V(E) and Δκs values are negative for the whole composition range at 293.15 K. And, the excess function follows the sequence: 2-butanol>1-butanol>2-methyl-2-propanol, which reveals that (primary or secondary or tertiary) position of hydroxyl group influence the magnitude of interactions with ILs. The negative values of excess functions are contributions from the ion-dipole interaction, hydrogen bonding and packing efficiency between the ILs and butanol isomers. Hence, the position of hydroxyl group plays an important role in the interactions with ILs. The hydrogen bonding features between ILs and alcohols were analysed using molecular modelling program by using HyperChem 7.
在本研究中，我们探索了氢氧化四烷基铵离子液体（ILs），如氢氧化四丙基铵（TPAH）和氢氧化四丁基铵（TBAH）与丁醇异构体（1 - 丁醇、2 - 丁醇和2 - 甲基 - 2 - 丙醇）在293.15 - 313.15 K温度范围内（间隔5 K）以及不同ILs浓度范围内的热物理性质。ILs与丁醇异构体之间的分子相互作用对于理解ILs在相关测量中的功能至关重要，而过量函数是分子相互作用的灵敏探针。因此，我们利用在五个不同温度（293.15、298.15、303.15、308.15和313.15 K）及大气压下在整个组成范围内测量的密度（ρ）和超声声速（u）等实验值，计算了过量摩尔体积（V(E)）和等熵压缩率偏差（Δκs）。这些过量函数通过Redlich - Kister多项式方程得到了充分关联。结果发现，对于所有研究的体系，在293.15 K时整个组成范围内V(E)和Δκs值均为负。并且，过量函数遵循以下顺序：2 - 丁醇＞1 - 丁醇＞2 - 甲基 - 2 - 丙醇，这表明羟基的（伯或仲或叔）位置会影响与ILs相互作用的强度。过量函数的负值源于ILs与丁醇异构体之间的离子 - 偶极相互作用、氢键和堆积效率。因此，羟基的位置在与ILs的相互作用中起着重要作用。使用HyperChem 7分子建模程序分析了ILs与醇类之间的氢键特征。
