FOOD CHEMISTRY
·
2020
·
IF 6.306
MengTing Zhu,Ting Shi,ZiYan Guo,HongXia Liao,Yi Chen
The oxidation of cold-pressed and commercial refined camellia oil stored at room temperature for one year was comparatively studied by 1 H and 31 P NMR spectroscopy. The oxidation of extra virgin olive oil (EVOO) under the same conditions was further compared. The 1 H NMR showed that no aldehydes were formed in the studied period. Coupled with the changes of unsaturated acyl groups, the oxidation degrees of the three oils could be obtained follow the order: commercial refined camellia oil > cold-pressed camellia oil > EVOO. The 31 P NMR showed that the evolution of diacylglycerols (DGs) and ratio D in commercial refined camellia oil was fairly different from other two oils. Besides, the kinetics curves of unsaturated acyl groups and ratio D both fit to an exponential equation with high coefficients which indicated that the oxidation of the studied oils progressed in an exponential way with storage time at room temperature.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2022
·Vol. 24
·期 34
·20073-20081
·
IF 3.945
Ruifen Shi,Fengyi Zhou,Yu Chen,Zhenghui Liu,Shuzi Liu,Tiancheng Mu
Deep eutectic solvents (DESs) are well-known as novel solvents due to their unique properties, which are indispensable for the development of green chemistry in the future. CoCl2·6H2O and NiCl2·6H2O-based DESs, which could be called magnetic DESs (MDESs) for short in view of their responsive behavior to an external magnetic field, have been widely used in many industrial applications, such as biomass treatment, electrolytes, and material preparation. For better application and full-scale development of these MDESs in various fields, eleven MDESs were prepared in this work by using CoCl2·6H2O and NiCl2·6H2O as hydrogen bond acceptors (HBAs) with alcohols, carboxylic acids and amides as hydrogen bond donors (HBDs), respectively. The intermolecular interactions between the components of MDESs were characterized via FTIR, 1H NMR and DSC analysis. In addition, physicochemical properties including density, viscosity, conductivity, ionicity, pH values, surface tension, thermostability and solvatochromic parameters were investigated. All MDESs exhibit acid characteristics and have good conductivity comparable with ionic liquids (ILs) and other DESs used for electrolytes. The results show that stronger H-bonding networks in Ni-based MDESs make them have higher density, viscosity, polarity and surface tension values than Co-based MDESs. Moreover, all prepared MDESs possess a good conductivity behavior which could be comparable to that of common organic solvents and ILs. According to this work, we could better comprehend the behavior of Co/Ni-based MDESs and choose the appropriate one for particular applications.
研究领域:
化学
·
材料科学
·
绿色化学
·
工业应用
✓ 已验证
DOI
高影响因子
Molecular Catalysis
·
2026
·
IF 4.3
Jiarong Zhang,Christian Marcus Pedersen,Shuwei Chen,Yingxiong Wang,Yan Qiao
A green epimerization system using only water and CaCl 2 . • NMR identifies products, by-products, and reveals the mechanism. • Isotope labeling and DFT confirm the epimerization pathway. • A direct route to ManNAc from a biomass monomer. N -acetyl- d -mannosamine (ManNAc) is a valuable precursor in the pharmaceutical and biotechnology industries. Enzymatic epimerization of N -acetyl- d -glucosamine (GlcNAc) offers mild and green conditions for ManNAc production, while its productivity is limited by poor enzyme stability and high costs. Although efficient chemical methods have been developed, they often require strict control of reaction conditions to avoid by-product formation, and their reaction mechanisms remain unclear. This study presents a green and efficient strategy for ManNAc synthesis through calcium chloride (CaCl 2 )-promoted epimerization of GlcNAc in aqueous solution. ManNAc production reached a yield of 27% under optimized conditions. The reaction mechanism was elucidated through a combination of nuclear magnetic resonance (NMR) spectroscopy and density functional theory (DFT) calculations. Using deuterium oxide (D 2 O) as the reaction medium revealed hydrogen-deuterium exchange at the C2 position of GlcNAc, providing direct experimental evidence for a reaction pathway involving an enol intermediate. This finding was further supported by subsequent 13 C isotopic labeling experiments. DFT calculations further revealed that water molecules play a critical role in mediating proton transfers, significantly reducing the energy barriers of the key steps of enol intermediate formation. CaCl 2 enhanced the yield by promoting the formation of the enol intermediate. Additionally, a preliminary investigation was conducted on the purification of ManNAc from the reaction mixture containing its structural epimers. This work not only provides a green system for ManNAc synthesis but also offers profound insights into the reaction mechanism, paving the way for developing more efficient biomass utilization strategies. Download: Download high-res image (515KB) Download: Download full-size image
✓ 已验证
产品关联
DOI
高影响因子
MATERIALS AND STRUCTURES
·
2026
·Vol. 59
·期 6
·303
·
IF 3.9
Yin Jianhao,Liao Jiaxin,Kong Xiangming
The composition, moisture distribution, and microstructural evolutions of calcium-silicate-hydrate (C–S–H) in synthetic C–S–H (SynCSH) and hardened tricalcium silicate paste (HC 3 SP) during the first drying-resaturation (D-R) cycle were systematically compared using low-field 1 H-nuclear magnetic resonance (LF-NMR) and thermogravimetric analysis (TGA). The stoichiometric formulas of C–S–H in SynCSH and HC 3 SP were determined as C 0.9 SH 3.65 and C 2.0 SH 4.53 , respectively. Water contents of C–S–H quantified by TGA and LF-NMR exhibit good linear relationship. Three types of water, interlayer water, gel water and capillary water in C–S–H were identified by LF-NMR. Notable observations included the abnormal increase of interlayer water during the drying process and subsequent decrease during resaturation, along with irreversible decreases in capillary water and increases in gel water after D-R cycle, which were attributed to the rearrangement of C–S–H layered structures. SynCSH exhibited collapse of capillary pore structures following the D-R cycle, resulting in irreversible reductions in total water content. This finding confirms the validity of synthetic C–S–H as a model material for cementitious C–S–H research while highlighting its limitations in predicting the microstructural stability of real cement pastes under moisture cycling.
✓ 已验证
产品关联
DOI
高影响因子
POLYMER TESTING
·
2022
·
IF 4.931
Kirill Alferov,Shuanjin Wang,Dongmei Han,Shanyue Guan,Min Xiao,Yuezhong Meng
Co-oligomers of carbon dioxide and propylene oxide with high carbonate content and terminated by hydroxyl groups are practically important polyols to synthesize block copolymers. Despite this, the 1 H and 13 C spectra of such co-oligomers have not been described in detail so far. In this article, a new metal-free synthesis of carbon dioxide/propylene oxide co-oligomers by a triethylborane/organic base (organic base is PPNCl) catalytic system in the presence of diols (1,2-propanediol, 1,4-butanediol) is briefly introduced. The resonances in the 1 H and 13 C NMR spectra of the synthesized products were assigned using 2D NMR spectrometry methods (COSY, TOCSY, selective HMBC, and HSQC). As a result, the signals of different types of chain ends and of propylene oxide units forming ether linkages were found in addition to the peaks of carbonate blocks. Moreover, our study confirmed the occurrence of an efficient chain transfer during the co-oligomerization, which is additionally supported by MALDI TOF mass spectrometry results.
研究领域:
化学
·
材料科学
✓ 已验证
DOI
高影响因子
MICROCHEMICAL JOURNAL
·
2026
·
IF 5.2
Mengjiao Wang,Haoyu Li,Lu Bai,Quan Guo,Jiayuan Wu,Chi-Tang Ho,Naisheng Bai,Sen Guo
The rapid and targeted identification of bioactive constituents from complex natural product matrices remains a significant challenge in natural product research. This study employs an integrated biochemometrics workflow combining 1 H Nuclear Magnetic Resonance ( 1 H NMR) and mass spectrometry (MS) to efficiently pinpoint antioxidant components from Aganosma cymosa . Systematic separation of the crude extract yielded 37 microfractions (MFs), which were subjected to both antioxidant activity evaluation and UHPLC-MS/MS profiling. An active molecular network was constructed by calculating Spearman rank correlation coefficients between MS feature abundances and the corresponding antioxidant activity data, enabling visualization of activity-correlated features within the GNPS platform. To address the limitation of MS-based annotation in distinguishing structural isomers, feature-based GNPS analysis was integrated with 1 H NMR heterospectral covariance analysis (HetCA). The HetCA pseudo-spectra provided orthogonal validation and precise spectroscopic targets for subsequent isolation. Through this combined strategy, the main antioxidant constituents were successfully predicted, isolated, and structurally verified by NMR data. In conclusion, this study demonstrates that the synergistic integration of Spearman rank correlation-based active molecular networking, a multi-level prioritization strategy, and 1 H NMR HetCA orthogonal validation provides a powerful paradigm for the precise identification of bioactive components in complex plant matrices.
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry A
·
2020
·Vol. 8
·期 32
·16515-16526
·
IF 11.301
Fushan Geng,Bei Hu,Chao Li,Chong Zhao,Olivier Lafon,Julien Trébosc,Jean-Paul Amoureux,Ming Shen,Bingwen Hu
The burgeoning Li-rich cation-disordered rock-salt (DRX) materials have great potential to serve as the cathodes for rechargeable lithium ion batteries. They generally possess high capacities thanks to the participation of both cationic and anionic redox reactions. However, most DRX materials are subject to a large irreversible capacity loss during the first cycle and an undesirable voltage hysteresis between charge and discharge. In this work, solid-state NMR spectroscopy is employed to resolve the manifold local environments in Li1.2Ti0.4Mn0.4O2 as a model sample, and electron paramagnetic resonance (EPR) spectroscopy is used to investigate its electronic properties. Very broad resonances are observed in the 7Li and 17O NMR spectra. The paramagnetic and diamagnetic Li environments are distinguished, and the loss of the diamagnetic Li signal is observed after the first cycle. The degradation mechanism involved with oxygen loss and transition metal migration is discussed. The formation of the (O2)n− species and electron holes on oxygen at high voltage is suggested by EPR, and the voltage hysteresis is attributed to the difficulty in reducing the stable O–O bonds. These findings may enrich the understanding of DRX materials to better design high-performance DRX cathodes.
研究领域:
材料科学
·
电化学
·
储能
·
电池技术
·
固体谱学
✓ 已验证
DOI
高影响因子
JOURNAL OF PHARMACEUTICAL AND BIOMEDICAL ANALYSIS
·
2022
·
IF 3.571
Xueni Zhong,Qianqian Lv,Qiyun Yong,Wenping Hu,Dan Li,Shuhui Ji,Liuyue Zhan,Wenbin Chen,Min Li,Jinsheng Lin,Cuirong Sun
Elagolix sodium (ELS) is a marketed product using to release moderate to severe endometriosis-associated pain. It contains functional groups such as carboxyl group , secondary amino group , 2,4-dioxo pyrimidinyl and several benzyl or benzyl-like position hydrogen atom that are susceptive to occur stress degradation. Forced degradation studies of ELS reveal different degradation profiles of the drug substance which are conducted under photo, thermal, acidic, neutral, alkaline and hydrogen peroxide oxidative conditions in the direction of the ICH guidances. With structural elucidation of LC-PDA/UV-MS n and NMR, the degradants were identified, and seven new degradants are reported in this study. It is confirmed that most of the degradation behaviors of ELS are related to the carboxyl group and secondary amino group in the 3-carboxyl propylamine side chain. Under the oxidative condition using hydrogen peroxide as the oxidant , the secondary amine was oxidized to form an N -hydrogen amine degradant and two further degradants of amine and carbonyl analogs were generated. Under the alkaline degradation condition, the ELS is proven to be stable and no obvious degradants are produced. On the other hand, under the acidic and neutral degradation condition, the 2,4-dioxo pyrimidinyl core of elagolix sodium is stable but the carboxyl group and secondary amine will occur ring cyclization to form the δ -lactam analogs of elagolix sodium. The plausible mechanisms for the degradation of acidic, thermal, photo-degradative and hydrogen peroxide mediated oxidative of elagolix sodium are proposed. It is worth to note that DP-3–4 are the potential degradants which are only found in the solution degradation and are not the real impurities of elagolix sodium.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MOLECULES
·
2021
·Vol. 26
·期 19
·5974
·
IF 4.412
Iryna S. Protsak,Yevhenii M. Morozov,Dong Zhang,Volodymyr M. Gun’ko
The investigation of molecular interactions between a silica surface and organic/inorganic polymers is crucial for deeper understanding of the dominant mechanisms of surface functionalization. In this work, attachment of various depolymerized polydimethylsiloxanes (PDMS) of different chain lengths, affected by dimethyl carbonate (DMC), to silica nanoparticles pretreated at different temperatures has been studied using29Si,1H, and13C solid-state NMR spectroscopy. The results show that grafting of different modifier blends onto a preheated silica surface depends strongly on the specific surface area (SSA) linked to the silica nanoparticle size distributions affecting all textural characteristics. The pretreatment at 400 °C results in a greater degree of the modification of (i) A-150 (SSA = 150 m2/g) by PDMS-10/DMC and PDMS-1000/DMC blends; (ii) A-200 by PDMS-10/DMC and PDMS-100/DMC blends; and (iii) A-300 by PDMS-100/DMC and PDMS-1000/DMC blends. The spectral features observed using solid-state NMR spectroscopy suggest that the main surface products of the reactions of various depolymerized PDMS with pretreated nanosilica particles are the (CH3)3SiO-[(CH3)2SiO-]xfragments. The reactions occur with the siloxane bond breakage by DMC and replacing surface hydroxyls. Changes in the chemical shifts and line widths, as shown by solid-state NMR, provide novel information on the whole structure of functionalized nanosilica particles. This study highlights the major role of solid-state NMR spectroscopy for comprehensive characterization of functionalized solid surfaces.Keywords:silica nanohybrids;solid-state NMR;surface properties;polydimethylsiloxane;silica functionalization
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2021
·
IF 7.963
Lin Shi,Di Zhang,Jinfeng Zhao,Jianliang Xue,Mengnan Yin,Aiping Liang,Bo Pan
The slower adsorption of lower molecular weight organic molecules remains poorly understood. This study investigated the adsorption kinetics of gallic acid (GA) and tannic acid (TA) on kaolinite (Kao), montmorillonite (Mon) and hematite (Hem), with an emphasis on the role of the bound water on the minerals. The lower adsorption of TA and GA on Kao than on Mon attributed to the lower specific surface area of Kao. Because of the electrostatic attraction, the adsorption of TA and GA on Hem was higher than that on Mon, even the specific surface area of the former was much lower than that of the later. The adsorption rates of TA on the three minerals were generally two orders of magnitude higher than those of GA. The adsorption kinetics of GA was strongly diffusion dependent; however, the diffusion process had limited influence on TA adsorption kinetics. The decreased c values of the intraparticle diffusion model of GA with increasing ionic strength provided additional direct evidence for the diffusion-dependent adsorption and the reduced hindrance by bound water via hydration layer compression. However, hydration layer compression had no effect on TA adsorption kinetics. The reduced 1 H NMR relaxation rate of bound water indicated that the bound water quantity on minerals decreased with increasing ionic strength, which proved the occurrence of hydration layer compression. This study highlighted the importance of bound water and the relative sizes of organic molecules in the adsorption kinetics of organic compounds on minerals, which should be carefully considered for their environmental fate studies.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2011
·Vol. 13
·期 32
·14542-14549
·
IF 3.454
Kelei Zhuo,Yujuan Chen,Jing Chen,Guangyue Bai,Jianji Wang
Extensive applications of ionic liquids (ILs) may result in their accumulation in the ecological environment and organisms. Although ILs are popularly called “green solvents”, their toxicity, in fact, has been exhibited. Therefore the interaction of ILs with biomolecules is a cutting-edge research subject. Herein, the interactions of 1-butyl-3-methylimidazolium carboxylate ionic liquids ([C4mim][HCOO], [C4mim][CH3COO] and [C4mim][CH3CH2COO]) with glucose in water were studied for their volumetric properties, viscosity, conductivity and NMR spectra. Limiting apparent molar volumes (V0Φ,IL), viscosity B-coefficients, limiting molar conductivities (Λ0) and Walden products (Λ0η0) were evaluated for the ILs in glucose + water solutions. Volumetric interaction parameters were also obtained from the transfer volumes of the ionic liquids. The contributions of the solvent properties (B1) and the ionic liquid–solvent interactions (B2) to the B-coefficient were extracted, together with molar activation energies (Δμ0≠IL) of the ionic liquids for viscous flow of the aqueous glucose + IL solution. In addition, the 13C and 1H NMR spectra of methyl β-D-glucopyranoside and ILs in β-D-glucopyranoside + IL + D2O were studied. The NMR results show that no special and strong interactions were observed between glucopyranoside and the ILs. However, it was confirmed that the H2 on the imidazolium ring has more activity (acidity) than atoms H4 and H5. The macro-properties and their changes were also discussed in terms of the size, structure and solvation of the ILs and glucose.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MAGNETIC RESONANCE IN CHEMISTRY
·
2017
·Vol. 56
·期 2
·73-79
·
IF 1.601
Xiaochen Tang,Yingjie Xu,Xiao Zhu,Yueqing Lu
In this work, changes in microstructure of two protic ionic liquids (PILs), namely n -butylammonium acetate (N4Ac) and n -butylammonium nitrate (N4NO 3 ), are proved by in situ variable-temperature 1 H NMR spectroscopy at the temperature range from 25 to 115 °C, and the influence of the nature of anion is discussed accordingly. The results demonstrate that 1 H NMR chemical shifts of alkyl protons of both N4Ac and N4NO 3 are almost not changed with the increasing of temperature, due to the absence of hydrogen bond interaction between alkyl protons with anions. Whereas those of + N―H of cation decrease linearly with the temperature increasing, indicating that the hydrogen bond interaction between + N―H and anion weakens gradually. In addition, the strength of hydrogen bond interaction between + N―H and NO 3 − is stronger than that between + N―H and Ac − , suggesting that anions have a significant influence on microstructure due to the acidity of a Brønsted acid. Consequently, the proton transfer from cation to anion is much easier in N4Ac compared to N4NO 3 . Further analyses of 1 H NMR chemical shifts of + N―H in N4Ac at the temperature range from 100 to 115 °C suggest that the splitting of + N―H peak may be attributed to obvious evidence of the existence of the proton transfer from + N―H to Ac − , which leads to dissociate the contact ion-pair in N4Ac to form the neutral ion-pair ‘molecule’. The results will help us to extensively understand the behavior of proton transfer and offer us some valuable information for the design of PILs. Copyright © 2017 John Wiley & Sons, Ltd.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）