RSC Advances
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2021
·Vol. 11
·期 39
·23846-23850
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IF 3.361
Rongshan Lan,Yiyang Liu,Ling Han,Jing Yang,Huiqin Yin,Min Ge,Xiaobin Fu,Hongtao Liu,Yuan Qian
In this study, by applying 19F, 23Na and 7Li high-resolution NMR methods, the evolution of the [ZrxFy]4x−y local ionic structures in FLiNaK–ZrF4 salt mixtures were elucidated. K3ZrF7, Na3ZrF7 and Na7Zr6F31 crystal phases were identified when the melt salts were being solidified. The distribution of these [ZrxFy]4x−y species was dependent on the content of ZrF4 in FLiNaK eutectic salts. Moreover, K3ZrF7 phase transition from an orthorhombic lattice into a disordered cubic lattice was clarified, thereby causing dynamics of the coordinated F− ions to be reduced and the well-ordered crystal lattices to be destroyed. These mentioned results provide a further insight into the Zr–F based ionic structure and the formation of the disordered Zr–F structure in ZrF4-based eutectic salts.
研究领域:
材料科学
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核能工程
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物理化学
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DOI
PubMed
高影响因子
ANALYTICAL CHEMISTRY
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2022
·
IF 8.008
Anqi He,Lei Ni,Hui Fu,Xiu Zhang,Zhen-Qiang Yu,Jun Song,Limin Yang,Yizhuang Xu,Yukihiro Ozaki,Isao Noda
When diffusion coefficients of different components in a mixture are similar, NMR spectra of pure individual components are difficult to be obtained via a diffusion-ordered spectroscopy (DOSY) experiment. Two-dimensional correlation spectroscopy (2D-COS) is used to analyze the data from the DOSY experiment. Through the properties of the systematic absence of cross-peak (SACP) in the 2D asynchronous spectra, spectra of pure components can be obtained even if their diffusion coefficients are similar. However, fluctuations in peak-position and peak-width are often unavoidable in NMR spectra, which makes SACPs unrecognizable. To address the problem, a 2D quotient spectrum is used to identify the masked SACPs. However, undesirable interference peaks due to the fluctuations in peak-position and peak-width are still present when we extract a spectrum of a component by slicing the 2D asynchronous spectrum across the SACP. A genetic algorithm (GA) is used to select a suitable subset of spectra where the diversities of peak-position and peak-width are significantly reduced. Then, we used the selected spectra to construct a refined 2D asynchronous spectrum so that the spectra of pure components with significant attenuated interference can be obtained. The above approach has been proven to be effective on a model system and a real-world example, demonstrating that 2D-COS possesses a bright perspective in the analysis of the bilinear data from DOSY experiments.
研究领域:
分析化学
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核磁共振波谱学
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数据分析
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DOI
PubMed
高影响因子
JOURNAL OF PHYSICAL CHEMISTRY B
·
2021
·
IF 2.991
Minjun Ma,Xueke Gao,Zhaohui Guo,Yan Qiao
Biotin–dendrimer conjugates (such as biotin-PAMAMs-NH2) are important macromolecules in the field of host–guest chemistry and widely used systems for delivery. The similar chemical structures of the inner and outer layers of PAMAM-NH2 make it difficult to illuminate the interaction and the binding affinity of biotin-PAMAMs-NH2. By utilizing NMR techniques including 1H NMR titration, CSSF-TOCSY, STDD methods, and 2D DOSY analysis, we demonstrate a method to sort out these interactions. The methylene protons of the inner and outer layers of PAMAM-NH2 are successfully identified and accurately positioned so that the carboxylic acid groups of biotins are having ionic interactions with the outermost amine groups of PAMAM-NH2. The inner PAMAM-NH2 is protonated when reaching the isoelectric point of PAMAM-NH2, increasing the hydrodynamic radius. On the basis of the NMR experiments, a model is proposed, where the carboxylic acid groups and heterocyclic skeleton of biotin arched over the outer layers of PAMAM-NH2 like a bridge. Furthermore, using STDD epitope mapping, the binding affinity between biotin and PAMAM-NH2 was quantified. The diffusion behavior of biotin-G5 PAMAM-NH2 complex is more complicated than that of biotin-G3 PAMAM-NH2 complex due to steric hindrance. The results provide a theoretical basis for understanding these complicated drug delivery systems.
研究领域:
化学
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药物递送系统
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分子相互作用
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DOI
高影响因子
ChemCatChem
·
2020
·Vol. 12
·期 15
·3880-3889
·
IF 4.853
Xingling Zhao,Jun Xu,Yueying Chu,Guodong Qi,Qiang Wang,Wei Gao,Shenhui Li,Ningdong Feng,Feng Deng
Graphical Methane activation : Different types of Ga-CH 3 species were observed in methane activation on Ga-modified ZSM-5 zeolite, evidencing different pathways for heterolytic cleavage of C−H bond of methane. Two-dimensional solid-state NMR experiments provided detailed information on the location and local environment of the Ga-CH 3 species. Methane activation on Ga-modified ZSM-5 zeolites (Ga/ZSM-5) was studied by solid-state NMR spectroscopy. Two types of Ga species, namely highly dispersed oxides and cationic Ga species, were determined by 71 Ga QCPMG NMR. The activation of methane on Ga/ZSM-5 was explored by using 13 C and 1 H MAS NMR. Four types of Ga-CH 3 species along with Ga-OH groups were observed on Ga/ZSM-5, evidencing different pathways for heterolytic cleavage of C−H bond of methane. Two-dimensional (2D) 1 H- 1 H correlation NMR experiments provide detailed information on the location and local environment of the Ga-CH 3 species by correlating the protons in Ga-CH 3 with those in Ga-OH and other hydroxyls on zeolite. The structures of different Ga-CH 3 species were further determined by 2D 1 H- 13 C heteronuclear correlation NMR experiments, which were supported by theoretical calculations. The activation routes of C−H bond in methane were proposed on Ga/ZSM-5 zeolite.
研究领域:
化学
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材料科学
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产品关联
DOI
高影响因子
CARBOHYDRATE RESEARCH
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2023
·
IF 3.1
Dayu Tian,Lan Huang,Zhao Zhang,Zhenfeng Tian,Shaolin Ge,Chenghui Wang,Yonghua Hu,Ying Wang,Jun Yang
Cellulose is an important component of tobacco ( Nicotiana tabacum L.) cell walls, which can be precursors for many harmful compounds in smoke. Traditional cellulose content analysis methods involve sequential extraction and separation steps, which are time-consuming and environmentally unfriendly. In this study, a novel method was first introduced to analyze cellulose content in tobacco via two-dimensional heteronuclear single quantum coherence (2D HSQC) NMR spectroscopy . The method was based on derivatization approach to allow the dissolution of insoluble polysaccharide fractions of tobacco cell walls in DMSO‑ d 6 /pyridine- d 5 (4:1 v/v) for NMR analysis. The NMR results suggested that besides the main NMR signals of cellulose, partial signals of hemicellulose including mannopyranose , arabinofuranose, and galactopyranose units could also be identified. In addition, the utilization of relaxation reagents has proved to be an effective way to improve the sensitivity of 2D NMR spectroscopy, which was beneficial for quantification of biological samples with limited quantities. To overcome the limitations of quantification using 2D NMR, the calibration curve of cellulose with 1,3,5-trimethoxybenzene as internal reference was constructed and thus the accurate measurement of cellulose in tobacco was achieved. Compared with the chemical method, the interesting method was simple, reliable, and environmentally friendly, which provided a new insight for quantitative determination and structure analysis of plant macromolecules in complex samples.
研究领域:
植物学
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分析化学
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烟草科学
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
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2021
·
IF 5.279
Pengfei Liu,Jiaojiao Zhang,Yan Qiao,Xianglin Hou,Yu Liu,Yingxiong Wang
Using environment-friendly catalysts to convert biomass into compounds with high values is one of the central topics of green chemistry. In this work, [Ch][Pro] (cholinium as the cation and l-proline as the anion) ionic liquid was synthesized and applied as a model catalyst in the production of deoxyfructosazine (DOF) and fructosazine (FZ) from d-glucosamine (GlcNH2). The 13C NMR chemical shift titration experiments and the diffusion-ordered NMR spectroscopy (DOSY) measurements showed that, when the [Ch][Pro] interacted with GlcNH2, the l-proline anion ([Pro]−) played a major catalytic role instead of cholinium cation ([Ch]+). The effects of the reaction temperature and the amount of [Ch][Pro] on the product yields were surveyed. The experimental results showed that the highest DOF yield (33.78%) was obtained after 30 min at 100 °C when the molar ratio of [Ch][Pro]/GlcNH2 was 1. Moreover, in situ1H NMR and in situ13C NMR experiments were applied to monitor the reaction process with [Ch][Pro] as the catalyst. The reactive intermediate, dihydrofructosazine, was clearly detected by these in situ techniques. Accordingly, a possible reaction pathway was proposed. By applying other amino acids as the anions, we also prepared five other [Ch][AA] ionic liquids, and they showed different catalytic activities and selectivity in the GlcNH2 self-condensation reaction.
研究领域:
绿色化学
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催化化学
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生物质转化
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DOI
PubMed
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
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2022
·
IF 6.633
Yingqing Zhao,Rui Liu,Christian Marcus Pedersen,Zhenzhou Zhang,Zhaohui Guo,Honghong Chang,Yingxiong Wang,Yan Qiao
Lactic acid (2-hydroxypropionic acid, LA) can be produced from abundant and renewable biomass resources via chemocatalytic processes, which exhibited high potential for meeting its tremendous demand in a wide range of applications. The basic Ba(OH) 2 could efficiently catalyze the conversion of d -glucose into LA. In the present study, by utilizing various NMR techniques including, chemical shift titration, 2D diffusion ordered spectroscopy (DOSY) analysis, heteronuclear singular quantum correlation ( 1 H– 13 C HSQC), the binding sites and catalytic interaction between d -glucose and catalyst were clarified. The experimental results by NMR and electrospray ionization mass spectrometry (ESI–MS) were used to explore the reaction mechanism. Experimental results disclosed that the catalyst, Ba(OH) 2 , may exist in the form of [Ba(OH)(H 2 O) 2 ] + under the reaction condition. The OH – of [Ba(OH)(H 2 O) 2 ] + is attached to the C5-O of d -glucose, and Ba 2+ is connected to the C1-O of d -glucose. Herein, we suppose that Ba(OH) 2 and d -glucose interact and form a complex, d -glucopyranose-[Ba(OH)(D 2 O) 2 ] + . Furthermore, when the reaction was performed in D 2 O, we were surprised to find that LA underwent varying degrees of deuteration. The reaction mechanism, binding sites and deuteration of the product have shed light on the efficient conversion of biomass to LA.
研究领域:
生物化学
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催化化学
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产品关联
DOI
高影响因子
Green Processing and Synthesis
·
2020
·Vol. 9
·期 1
·650-663
·
IF 1.672
Wanwan Wang,Jibao Cai,Zhenyu Xu,Yi Zhang,Fanchao Niu,Miao Gao,Jun Yang
A method was developed for rapid qualitative determination of lignocellulose in the tobacco cell wall by utilizing 2D heteronuclear single quantum coherence NMR spectra (2D HSQC NMR). Traditional methods for analyzing the structure of lignocellulose involve many steps of separation and extraction, which is labor-intensive. In this work, the whole cell wall was milled and dissolved in deuterium solvent. The solvent dimethylsulfoxide (DMSO-d 6 ) containing hexamethylphosphoramide (HMPA-d 18 ) enhanced swelling of the sample and gave high-resolution spectra. The tobacco samples are ball milled at different ball milling times, and the state of the particles is observed through an electron microscope, and then the probability of the particles being less than 5 µm is counted. Through the comparison of the abundance and integration of the peak signals in the spectra under different transmittances, it was determined that when the milling time was 6 h, the quality of the NMR spectra was the best. The optimum conditions of characterizing tobacco structure were DMSO-d 6 /HMPA-d 18 solution and 6 h milling time. Under these conditions, complete representation of the structure of lignocellulose and simplified process could be achieved. Graphical abstract
研究领域:
植物学
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生物化学
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DOI
高影响因子
JOURNAL OF PHARMACEUTICAL AND BIOMEDICAL ANALYSIS
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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.
研究领域:
药物化学
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分析化学
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药学
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF PHYSICAL CHEMISTRY B
·
2014
·
IF 3.377
Tianfu Li,Naimin Shao,Yuntao Liu,Jingjing Hu,Yu Wang,Li Zhang,Hongli Wang,Dongfeng Chen,Yiyun Cheng
We investigate the interactions of generation 3 (G3) poly(amidoamine) (PAMAM) and G3 poly(propylenimine) (PPI) dendrimers with sodium dodecyl sulfate (SDS) in aqueous solution. Size and structure of the dendrimer–SDS aggregates as a function of SDS/dendrimer molar ratio were revealed by SAXS and NMR. G3 PAMAM has a relatively open and dense-core structure, while G3 PPI with the same number of surface amine groups possesses a compact and uniform structure. Upon addition of SDS, much more SDS monomers were encapsulated in the interior of PPI rather than in PAMAM. More significant size increase in PAMAM–SDS aggregate is observed at low SDS concentrations, due to the binding of SDS on PAMAM surface and further assembly into larger supramolecular structures. Both noncooperative and cooperative binding of SDS on G3 PPI surface are observed, while only noncooperative binding is proposed on G3 PAMAM, due to its open surface and large surface group distance. The size of the PPI–SDS complex is larger than that of PAMAM–SDS at higher SDS concentrations. Within the investigated SDS concentrations, SDS exhibits much stronger interactions with G3 PPI than with G3 PAMAM. These results provide new insights into dendrimer–surfactant interactions and explain why PPI is much more cytotoxic than PAMAM.
研究领域:
生物化学
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材料科学
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分子生物学
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
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2021
·
IF 6.165
Hui Ma,Dan Luo,Qi Zhao,Rui Liu,Zhenzhou Zhang,Xianglin Hou,Xiaohuan Sun,Yingxiong Wang
Diffusion-ordered spectroscopy (DOSY) is a powerful and efficient technique for the analysis of complex mixtures, relying on their differential in self-diffusion coefficient. However, DOSY is often struggled to separate signals pertaining to isomeric species, especially positional isomers. Here, for the first time, we describe the novel design of 18-crown ether-6 (18C6) and 18C6/K + complex as matrixes to discriminate and identify positional isomeric mixtures of phenylenediamine, nitroaniline, phthalic acid, dimethoxybenzoic acid, aminophthalic acid and even amino acids using 1 H DOSY spectrum. The superior performance of 18C6 and 18C6/K + complex as matrix depends on that they can interact with different components with varying binding energy as demonstrated by MMMF calculations and the DFT calculation. The methodology presented here is simple yet efficient. Moreover, the crown ether and crown ether/K + complex provide the dual mode discrimination for both amino and carboxylic substituted positional isomers.
研究领域:
分析化学
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物理化学
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产品关联
DOI
高影响因子
JOURNAL OF PHYSICAL CHEMISTRY B
·
2016
·
IF 3.187
Bijun Liu,Lan Dong,Qianhong Yu,Xingliang Li,Fengchang Wu,Zhaoyi Tan,Shunzhong Luo
Glyphosate [N-(phosphonomethyl)glycine] has been described as the ideal herbicide because of its unique properties. There is some conflicting information concerning the structures and conformations involved in the protonation process of glyphosate. Protonation may influence the chemical and physical properties of glyphosate, modifying its structure and the chemical processes in which it is involved. To better understand the species in solution associated with changes in pH, thermodynamic study (potentiometry, calorimetry and NMR spectroscopy) about the protonation pathway of glyphosate is performed. Experimental results confirmed that the order of successive protonation sites of totally deprotonated glyphosate is phosphonate oxygen, amino nitrogen, and finally carboxylate oxygen. This trend is in agreement with the most recent theoretical work in the literature on the subject ( J. Phys. Chem. A 2015,, 119, 5241−5249). The result is important because it confirms that the protonated site of glyphosate in pH range 7–8, is not on the amino but on the phosphonate group instead. This corrected information can improve the understanding of the glyphosate chemical and biochemical action.
研究领域:
化学
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环境科学
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生物学
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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）