Hydration States of Cholinium Phosphate-Type Ionic Liquids as a Function of Water Content

2019 ◽  
Vol 72 (5) ◽  
pp. 392 ◽  
Author(s):  
Yohsuke Nikawa ◽  
Seiji Tsuzuki ◽  
Hiroyuki Ohno ◽  
Kyoko Fujita
Keyword(s):  
Ionic Liquids ◽  
Water Content ◽  
Alkyl Chain ◽  
Hydroxyl Group ◽  
Water Molecules ◽  
Hydroxyl Groups ◽  
Ion Structure ◽  
Activity Measurements ◽  
Microscopic Interactions ◽  
Dynamics Simulations

We investigated the hydration states of cholinium phosphate-type ionic liquids (ILs) in relation to ion structure, focusing on the influence of the hydroxyl group of the cation and the alkyl chain length of the anion. Water activity measurements provided information on the macroscopic hydration states of the hydrated ILs, while NMR measurements and molecular dynamics simulations clearly showed the microscopic interactions and coordination of the water molecules. The hydrogen bonding networks in these ILs were influenced by the anion structure and water content, and the mobility of water molecules was influenced by the number of hydroxyl groups in the cation and anion.

scholarly journals Ionic Liquids Based on Chromotropic Acid: Excellent Lubricating Additives for Aqueous System

2021 ◽  
Author(s):  
Peng Wang ◽  
Peng Gao ◽  
Lin Ma ◽  
Ping Wen ◽  
Yunyan Han ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Water Solubility ◽  
Aqueous System ◽  
Chromotropic Acid ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Load Carrying ◽  
Metal Friction ◽  
Lubricating Properties ◽  
Tribochemical Films

Abstract In this paper, four ionic liquids based on chromotropate (CAILs) were prepared and applied to heighten the tribological performance of aqueous system on different metal friction contacts. Taking for the potential choice for water-based lubricating additive, CAILs exhibited excellent water solubility and corrosion resistance. Tribological results showed that the CAILs, especially the phenolic hydroxyl group decorated samples (TsnN4444 and TsnP4444), demonstrated extremely effective lubricating properties with the efficient friction and wear descent (69% and 83% for Fe, 47% and 94% for Cu, 74% and 69% for Al, respectively). Especially, the excellent load-carrying capacity was also presented with the highest PB (833N) and PD (1568N) values for TsnP4444. It is speculated that the CAIL molecular adsorption on the interface and further generation of tribochemical films are beneficial for their lubricating effects. resulting from the systematic discussion and analysis of CA, QCM, SEM, XPS, and FIB-TEM tests. However, TsN4444 and TsP4444 showed less effective lubricating performances and poor load-carrying capacities due to tribocorrosion of hydroxyl groups at the interface.

Molecular Dynamics Study of Diffusion Behavior in Amorphous Silica with Hydroxyl Group

2008 ◽  
Vol 368-372 ◽  
pp. 1677-1679
Author(s):  
Fan Wei Zhang ◽  
Qui Ang Zhu ◽  
Yuan Fa Ding ◽  
Yue Zhang ◽  
Da Hai Zhang ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Amorphous Silica ◽  
Hydroxyl Group ◽  
Theoretical Interpretation ◽  
Hydroxyl Groups ◽  
Diffusion Behavior ◽  
Self Diffusion ◽  
Initial Charge ◽  
Dynamics Simulations

Molecular dynamics simulations are performed to research the diffusion behavior of amorphous silica with hydroxyl group. Muliken analysis is employed for the determination of initial charge status of simulated systems with various hydroxyl contents. Modified BKS potentials for the interactions between introduced hydroxyl groups and other atoms, are adopted in the present molecular dynamics simulations. Short-range atomic arrangement and self diffusion coefficients of hydroxyl-doped amorphous silica systems are calculated and hereafter compared with those of pure amorphous silica. The calculation results suggest that the doped hydroxyl groups play an important role for the mobility of atoms within the system, which can be employed to the theoretical interpretation of the oxidation process of the ceramics such as silicon nitride.

scholarly journals Ionic Liquids: Efficient Media for the Lipase-Catalyzed Michael Addition

Molecules ◽  
2018 ◽  
Vol 23 (9) ◽  
pp. 2154 ◽  
Author(s):  
Yunchang Fan ◽  
Dongxu Cai ◽  
Xin Wang ◽  
Lei Yang
Keyword(s):  
Ionic Liquids ◽  
Lipase Activity ◽  
Michael Addition ◽  
Alkyl Chain ◽  
Hydroxyl Group ◽  
Domain Formation ◽  
High Chemical ◽  
Chemical Structures ◽  
Reaction Media ◽  
High Chemical Stability

Recently, ionic liquids (ILs) have been regarded as ideal media for non-aqueous bio-catalysis. In this work, the synthesis of warfarin by the lipase-catalyzed Michael addition in IL media and the parameters that affected the warfarin yield were investigated. Experimental results demonstrated that the chemical structures of the ILs were a major factor for influencing the warfarin yield. The ILs containing the NTf2– anion were suitable reaction media due to the high chemical stability of this anion. The incorporation of the hydroxyl group on the IL cation significantly improved the lipase activity due to the H2O-mimicking property of this group. The lipase activity decreased by increasing the alkyl chain length on the IL cation due to the non-polar domain formation of the IL cation at the active site entrance of lipase. The ILs and lipase could be reused no less than five times without reduction in the warfarin yield.

scholarly journals Computational Assessment of Modified Antifreeze Glycoproteins on Ice Nucleation

Biophysica ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 168-178
Author(s):  
Monika Bleszynski ◽  
Matt Reil
Keyword(s):  
Separation Distance ◽  
Ice Nucleation ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Antifreeze Glycoproteins ◽  
Crystallization Inhibition ◽  
Nucleation Activity ◽  
Dynamics Simulations ◽  
Ice Nucleation Activity ◽  
Ice Crystallization

Antifreeze glycoproteins (AFGPs) found in various fish are used by the organisms to prevent freezing. While these compounds have been studied for their ability to bind to, and prevent the complete crystallization of water, the exact mechanisms by which AFGPs prevent freezing are still undetermined. Therefore, building upon our previous work, this study uses molecular dynamics simulations to assess the effects of hydroxyl group separation distance on AFGP ice nucleation activity. Water droplet crystallization simulations showed that modified AFGP structures containing hydroxyl distances smaller than ~3.0 Å lost their ability to prevent ice crystallization. Furthermore, modified AFGP containing hydroxyl distances of 7.327 Å and 6.160 Å was correlated with a promotion in ice nucleation, as demonstrated by the changes in the energy of the system. This supports the notion that the distance, and therefore, geometry characteristics between the hydroxyl groups located on the saccharide structures play a key role in the ice crystallization inhibition properties of AFGP compounds.

Towards clathrates. 2. The frozen states of hydration of tert-butanol

2018 ◽  
Vol 233 (1) ◽  
pp. 41-49 ◽  
Author(s):  
Lukasz Dobrzycki
Keyword(s):  
Single Crystal ◽  
Crystalline Phase ◽  
Ambient Pressure ◽  
Water System ◽  
Hydroxyl Group ◽  
Molar Ratio ◽  
Water Molecules ◽  
Hydroxyl Groups ◽  
Hydrogen Atoms ◽  
Ir Laser

AbstractA new crystal structure oftert-butanol and water crystallizing as the decahydrate is reported. The crystallization of the mixture in the desired molar ratio was performed in a capillary placed directly on a goniometer of a single crystal diffractometer at 200 K and ambient pressure using focused IR laser radiation. The crystals were grown while the melting zone formed by the IR laser was moved along the capillary. Usually the crystallization process should be long enough (hours) in order to obtain a good quality single crystal. However, in the case oftert-butanol decahydrate, such a long process led to separation of the ice and alcohol. Only fast crystallization taking tens of seconds allowed crystallization of the desired crystalline phase. In the decahydratetert-butanol molecules are located in channels formed by water molecules. Hydroxyl groups are anchored to the water framework via hydrogen bonds. All water molecules in the structure have hydrogen atoms disordered equally over two sites; the hydroxyl group is likewise disordered. This effect is observed at both, 200 K and 100 K. Raman spectra recorded for the crystalline phase suggest dynamic disorder at higher temperature, converting to static at lowerT. The decahydrate oftert-butanol, together with already known itsdi- andhepta-hydrates, display similar features to those observed for series oftert-butylamine hydrates. The latter structures behave as frozen steps of amine hydration observed as crystal structures leading, at maximum dilution, to hexagonal ice. Hydrates oftert-butanol nicely follow this tendency completing the relationship found for thetert-butylamine: water system.

Study on the Structure and Spectrum of Water in 1-Ethyl-3-Methylimidazolium Tetrafluoroborate Ionic Liquids

2011 ◽  
Vol 271-273 ◽  
pp. 92-97
Author(s):  
Guo Cai Tian ◽  
Zhi Liang Jiao ◽  
Ya Dong Li
Keyword(s):  
Molecular Dynamics ◽  
Distribution Function ◽  
Correlation Function ◽  
Ionic Liquids ◽  
Blue Shift ◽  
Water Molecules ◽  
Water Mixture ◽  
Velocity Correlation ◽  
Velocity Correlation Function ◽  
Dynamics Simulations

Various 1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim]BF4)/water mixture with varying concentrations were studied by molecular dynamics simulations. The radial distribution function, the power spectrum velocity-velocity correlation function were calculated to reveal the microstructure and the IR spectrum. In both liquids, with the concentration of water in the mixture increase, the rotation bands and the bending bands of water are red shift whereas the O-H stretch bands are blue shift. It was found that the molecular rotation motions become slower as the proportion of water increases and water molecules tend to be isolated from each other in mixtures with more ions than water molecules. It was shown that water molecules tend to be isolated from each other in mixtures with more ions than water molecules in both liquids.

scholarly journals Effects of pH on High-Performance ZnO Resistive Humidity Sensors Using One-Step Synthesis

Sensors ◽  
2019 ◽  
Vol 19 (23) ◽  
pp. 5267 ◽  
Author(s):  
Yu ◽  
Zhang ◽  
Zhang ◽  
Li
Keyword(s):  
High Performance ◽  
Oxygen Vacancies ◽  
Humidity Sensor ◽  
Ph Value ◽  
Precursor Solution ◽  
Hydroxyl Group ◽  
Water Molecules ◽  
Hydroxyl Groups ◽  
Humidity Sensors ◽  
One Step

In this paper, we prepared a high-performance zinc oxide (ZnO) humidity sensor in an alkaline environment using one-step hydrothermal method. Experiments showed that the pH value of the precursor solution affects the performance of ZnO humidity sensors. There are abundant hydroxyl group and oxygen vacancies on the surface of ZnO with a precursor pH value of 10. Abundant hydroxyl groups on the surface of ZnO can adsorb a large number of water molecules and rich oxygen vacancies can accelerate the decomposition of water molecules, thus increasing the number of conductive ions (H3O+) and further improving the performance of the sensor. So, such a ZnO humidity sensor exhibited high sensitivity (14,415), good linearity, small hysteresis (0.9%), fast response/recovery time (31/15 s) in the range from 11% to 95% relative humidity (RH). Moreover, the ZnO-2 humidity sensor has good repeatability and can be effectively used for a long time. This study provides a new idea for the development of low-cost, high-performance and reusable ZnO resistive humidity sensors.

Influence of hydroxyl group functionalization and alkyl chain length on physicochemical and antiwear properties of hexafluorophosphate imidazolium ionic liquids

2014 ◽  
Vol 66 (3) ◽  
pp. 443-451 ◽  
Author(s):  
Yanqiu Xia ◽  
Zhihong Wang ◽  
Yanxin Song
Keyword(s):  
Ionic Liquids ◽  
Chain Length ◽  
Corrosion Behavior ◽  
Friction And Wear ◽  
Alkyl Chain ◽  
Electrochemical Corrosion ◽  
Alkyl Chain Length ◽  
Hydroxyl Group ◽  
Content Type ◽  
Electrochemical Corrosion Behavior

Purpose – The aim of the present paper is that three long-chain hydroxyethyl alkylimidazolium hexafluorophosphate ionic liquids (ILs) were synthesized and evaluated as lubricants for steel-steel contacts at room temperature and boundary lubrication conditions. Hydroxyethyl functional group and alkyl chain length effect on the physicochemical and fretting tribological behaviors of the ILs was comparatively investigated, as compared to traditional dialkylimidazolium ILs. Design/methodology/approach – The fretting friction and wear tests were carried out using an Optimol SRV-IV oscillating reciprocating friction and wear tester. The worn surface was observed and analyzed by scanning electron microscope and X-ray photoelectron spectroscopy. The electrochemical corrosion behavior of copper disks in selected imidazolium-based ionic liquids was studied using a CHI660B electrochemical workstation. Findings – This can be seen by comparing the results for the non-hydroxyl ILs and hydroxyl ILs that the latter exhibited the littler friction coefficient, the smaller wear volume, although the latter electrochemical corrosion behavior of copper disks is slightly higher than the former. The results also revealed that the ILs with a longer alkyl chain displayed larger viscosities, better anti-corrosion capacities, higher hydrophobic properties and more excellent friction-reducing and anti-wear performance than those with a shorter alkyl chain. Originality/value – This work might offer new knowledge in the design and application of new ILs as lubricants; it also confirms some in-depth physicochemical questions, e.g. the function mechanism, the correlations between structure and performance. Additionally, a proposed interaction model between the ILs and the friction substrate has been given.

scholarly journals Heterogeneous ice nucleation correlates with bulk-like interfacial water

2019 ◽  
Vol 5 (4) ◽  
pp. eaat9825 ◽  
Author(s):  
Shuwang Wu ◽  
Zhiyuan He ◽  
Jinger Zang ◽  
Shenglin Jin ◽  
Zuowei Wang ◽  
...  
Keyword(s):  
Energy Barrier ◽  
Bound Water ◽  
Ice Nucleation ◽  
Hydroxyl Group ◽  
Water Molecules ◽  
Hydroxyl Groups ◽  
Interfacial Water ◽  
New Strategy ◽  
Group Density ◽  
Heterogeneous Ice Nucleation

Establishing a direct correlation between interfacial water and heterogeneous ice nucleation (HIN) is essential for understanding the mechanism of ice nucleation. Here, we study the HIN efficiency on polyvinyl alcohol (PVA) surfaces with different densities of hydroxyl groups. We find that the HIN efficiency increases with the decreasing hydroxyl group density. By explicitly considering that interfacial water molecules of PVA films consist of “tightly bound water,” “bound water,” and “bulk-like water,” we reveal that bulk-like water can be correlated directly to the HIN efficiency of surfaces. As the density of hydroxyl groups decreases, bulk-like water molecules can rearrange themselves with a reduced energy barrier into ice due to the diminishing constraint by the hydroxyl groups on the PVA surface. Our study not only provides a new strategy for experimentally controlling the HIN efficiency but also gives another perspective in understanding the mechanism of ice nucleation.

Tribological Performance of Ionic Liquids Bearing Hydroxyl Groups as Lubricants in the Aluminum-on-Steel Contacts

2010 ◽  
Vol 146-147 ◽  
pp. 1147-1153 ◽  
Author(s):  
Xi Feng Li ◽  
Zong Gang Mu ◽  
Xiao Xuan Wang ◽  
Shu Xiang Zhang ◽  
Yong Min Liang ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Friction And Wear ◽  
Tribological Performance ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Test Results ◽  
Alkyl Chains ◽  
Imidazolium Cations ◽  
Boundary Films ◽  
Aluminum Surfaces

A series of room temperature ionic liquids bearing hydroxyl groups, namely 1-(3’-hydroxyl-n-propyl)-3-alkylimidazolium tetrafluoroborate or hexafluorophosphate, were prepared and characterized. Their typical physical properties were also determined. The tribological test results show that these ionic liquids possess better friction-reducing and anti-wear ability for aluminum-on-steel system than lubricant X-1P. The friction coefficients of them are little higher than that of the nonfunctionlized ionic liquid LP308, while they possess better anti-wear abilities than the latter, which may ascribe to the chemical activity of hydroxyl group. Both the anions and the side substituted alkyl chains attached to the imidazolium cations affect the tribological performance of the lubricants. The SEM, EDS and XPS analysis of the worn surfaces show that complicated tribo-chemical reactions were involved in the sliding process. The boundary films composed of fluorides, nitrogen oxide, BN, and FePO4 were generated on the rubbing aluminum surfaces, which contribute to effectively decreasing the friction and wear of the contacts.

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