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Molecular Liquids in China

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Molecular Liquids".

Deadline for manuscript submissions: closed (15 November 2023) | Viewed by 5184

Special Issue Editor


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Guest Editor
Institute of Bast Fiber Crops and Center of Southern Economic Crops, Chinese Academy of Agricultural Sciences, Changsha 410205, China
Interests: bioactive ingredients in food resources; food packaging; food preservation; biodegradable materials; green solvents; deep eutectic solvents; ionic liquids; bio-based solvents; solid–liquid extraction; liquid–liquid extraction
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Special Issue Information

Dear Colleagues,

This Special Issue of the journal Molecules, entitled “Molecular Liquids in China”, deals with a wide range of areas from fundamental to applied research, including topics such as the structure, interactions, and dynamics of simple liquid. It is devoted to reporting on the knowledge of simple liquids or liquid mixtures comprised of molecular and/or ionic fluids, as well as corresponding experimental and theoretical methods.

Scientists from China are cordially invited to contribute original research papers or reviews to this Special Issue of Molecules, which reports on the experimental and/or computer simulations that contribute to the characterization and understanding of the fundamentals of liquids. The subjects on solvation, water and hydrogen bonds, ionic liquids, and liquid–liquid and solid–liquid interfaces are encouraged.

Prof. Dr. Zhijian Tan
Guest Editor

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • ionic liquids
  • organic liquids
  • deep eutectic solvents
  • bio-based solvents
  • switchable solvents
  • surfactant and colloidal solutions
  • water and aqueous solutions
  • thermotropic and lyotropic liquid crystals
  • supercritical fluids
  • subcritical fluids

Published Papers (4 papers)

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Research

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18 pages, 4039 KiB  
Article
Self-Assembly of Palmitic Acid in the Presence of Choline Hydroxide
by Huifang Xu, Xin Liang, Song Lu, Meihua Gao, Sijia Wang and Yuanyuan Li
Molecules 2023, 28(22), 7463; https://doi.org/10.3390/molecules28227463 - 07 Nov 2023
Viewed by 775
Abstract
To disperse fatty acids in aqueous solution, choline, a quaternary ammonium ion, has been used recently. So far, only the self-assembly of myristic acid (MA) in the presence of choline hydroxide as a function of the molar ratio has been investigated, and, thus, [...] Read more.
To disperse fatty acids in aqueous solution, choline, a quaternary ammonium ion, has been used recently. So far, only the self-assembly of myristic acid (MA) in the presence of choline hydroxide as a function of the molar ratio has been investigated, and, thus, the current understanding of these fatty acid systems is still limited. We investigated the self-assembly of palmitic acid (PA) in the presence of choline hydroxide (ChOH) as a function of the molar ratio (R) between ChOH and PA. The self-assemblies were characterized by phase contrast microscopy, cryo-TEM, small-angle X-ray scattering, and 2H NMR. The ionization state of PA was determined by pH, conductivity, and FT-IR measurements. With increase in R, various self-assembled structures, including vesicles, lamellar phase, rigid membranes (large sheets, tubules, cones, and polyhedrals), and micelles, form in the PA/ChOH system, different from those of the MA/ChOH system. The change in R induces pH variation and, consequently, a change in the PA ionization state, which, in turn, regulates the molecular interactions, including hydrogen bonding and electrostatic interaction, leading to various self-assemblies. Temperature is an important factor used to tune the self-assembly transitions. The fatty acid choline systems studied here potentially may be applicable in medicine, chemical engineering, and biotechnology. Full article
(This article belongs to the Special Issue Molecular Liquids in China)
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11 pages, 2366 KiB  
Article
The Spontaneous Vesicle–Micelle Transition in a Catanionic Surfactant System: A Chemical Trapping Study
by Qihan Sun, Jiani Gong, Yujia Sun, Yao Song, Changyao Liu and Baocai Xu
Molecules 2023, 28(16), 6062; https://doi.org/10.3390/molecules28166062 - 15 Aug 2023
Cited by 2 | Viewed by 739
Abstract
Typically, the formation of vesicles requires the addition of salts or other additives to surfactant micelles. However, in the case of catanionic surfactants, unilamellar vesicles can spontaneously form upon dilution of the micellar solutions. Our study explores the intriguing spontaneous vesicle-to-micelle transition in [...] Read more.
Typically, the formation of vesicles requires the addition of salts or other additives to surfactant micelles. However, in the case of catanionic surfactants, unilamellar vesicles can spontaneously form upon dilution of the micellar solutions. Our study explores the intriguing spontaneous vesicle-to-micelle transition in catanionic surfactant systems, specifically cetyltrimethyl ammonium bromide (CTAB) and sodium octylsulfonate (SOS). To gain insights into the changes occurring at the interface, we employ a chemical trapping method to characterize variations in the molarities of sulfonate headgroups, water, and bromide ions during the transition. Our findings reveal the formation of ion pairs between the cationic component of CTAB and the anionic component of SOS, leading to tight interfacial packing in CTAB/SOS solutions. This interfacial packing promotes vesicle formation at low surfactant concentrations. Due to the significant difference in critical micelle concentration (cmc) between CTAB and SOS, an increase in the stoichiometric surfactant concentration results in a substantial rise in the SOS-to-CTAB ratio within the interfacial region. This enrichment of SOS in the aggregates triggers the transition from vesicles to micelles. Overall, our study may shed new light on the design of morphologies in catanionic and other surfactant systems. Full article
(This article belongs to the Special Issue Molecular Liquids in China)
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14 pages, 3376 KiB  
Article
Study on Process Optimization and Antioxidant Activity of Polysaccharide from Bletilla striata Extracted via Deep Eutectic Solvents
by Liru Luo, Wei Fan, Jingping Qin, Shiyin Guo, Hang Xiao and Zhonghai Tang
Molecules 2023, 28(14), 5538; https://doi.org/10.3390/molecules28145538 - 20 Jul 2023
Cited by 5 | Viewed by 1091
Abstract
Taking the extraction yield of Bletilla striata polysaccharide (BSP) as the index and taking the type of deep eutectic solvents (DESs), extraction time, extraction temperature, DES water content, and solid–liquid ratio as the investigation factors, single-factor and Box–Behnken response surface tests were carried [...] Read more.
Taking the extraction yield of Bletilla striata polysaccharide (BSP) as the index and taking the type of deep eutectic solvents (DESs), extraction time, extraction temperature, DES water content, and solid–liquid ratio as the investigation factors, single-factor and Box–Behnken response surface tests were carried out to optimize the extraction process of BSP. Thus, the antioxidant activity of BSP on DPPH radicals, ABTS radicals and ferric reducing antioxidant power were determined. The results showed that the most suitable deep eutectic solvent was DES-2, namely choline chloride-urea. The optimal extraction conditions for BSP were an extraction time of 47 min, extraction temperature of 78 °C, water content of 35%, and solid–liquid ratio of 1:25. Under this optimized condition, the extraction yield of BSP was able to reach (558.90 ± 8.83) mg/g, and recycling studies indicated the good cycle stability of the DES. Antioxidant results showed that BSP had superior antioxidant activity and had a dose–response relationship with drug concentration. Compared with Bletilla striata polysaccharide obtained via conventional hot water extraction (BSP-W), the extraction yield of BSP obtained through this method (BSP-2) increased by 36.77%, the scavenging activity of DPPH radicals increased by 24.99%, the scavenging activity of ABTS radicals increased by 41.16%, and the ferric reducing antioxidant power increased by 49.19%. Therefore, DESs as new green reagents and BSP extracted with DESs not only had a high yield but also had strong antioxidant activity. Full article
(This article belongs to the Special Issue Molecular Liquids in China)
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Review

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23 pages, 8228 KiB  
Review
Tuning Ionic Liquid-Based Catalysts for CO2 Conversion into Quinazoline-2,4(1H,3H)-diones
by Ruina Zhang, Daqing Hu, Ying Zhou, Chunliang Ge, Huayan Liu, Wenyang Fan, Lai Li, Biao Chen, Yepin Cheng, Yaoji Chen, Wei Zhang, Guokai Cui and Hanfeng Lu
Molecules 2023, 28(3), 1024; https://doi.org/10.3390/molecules28031024 - 19 Jan 2023
Cited by 4 | Viewed by 2117
Abstract
Carbon capture and storage (CCS) and carbon capture and utilization (CCU) are two kinds of strategies to reduce the CO2 concentration in the atmosphere, which is emitted from the burning of fossil fuels and leads to the greenhouse effect. With the unique [...] Read more.
Carbon capture and storage (CCS) and carbon capture and utilization (CCU) are two kinds of strategies to reduce the CO2 concentration in the atmosphere, which is emitted from the burning of fossil fuels and leads to the greenhouse effect. With the unique properties of ionic liquids (ILs), such as low vapor pressures, tunable structures, high solubilities, and high thermal and chemical stabilities, they could be used as solvents and catalysts for CO2 capture and conversion into value-added chemicals. In this critical review, we mainly focus our attention on the tuning IL-based catalysts for CO2 conversion into quinazoline-2,4(1H,3H)-diones from o-aminobenzonitriles during this decade (2012~2022). Due to the importance of basicity and nucleophilicity of catalysts, kinds of ILs with basic anions such as [OH], carboxylates, aprotic heterocyclic anions, etc., for conversion CO2 and o-aminobenzonitriles into quinazoline-2,4(1H,3H)-diones via different catalytic mechanisms, including amino preferential activation, CO2 preferential activation, and simultaneous amino and CO2 activation, are investigated systematically. Finally, future directions and prospects for CO2 conversion by IL-based catalysts are outlined. This review is benefit for academic researchers to obtain an overall understanding of the synthesis of quinazoline-2,4(1H,3H)-diones from CO2 and o-aminobenzonitriles by IL-based catalysts. This work will also open a door to develop novel IL-based catalysts for the conversion of other acid gases such as SO2 and H2S. Full article
(This article belongs to the Special Issue Molecular Liquids in China)
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