NANOTECHNOLOGY
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2022
·Vol. 33
·期 21
·215705
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IF 3.953
Zhen Mao,Hui Li,Na Gan,Zili Suo,Huan Zhang,Qiang Zhao
Fixed carbon source and different dopants are mainly used to study the effect of heteroatoms on the structure and properties of carbon dots (CDs). As reactants, some dopants with conjugated structure and high nitrogen content may have important contributions to the structure and properties of doped CDs in addition to providing heteroatoms. Herein, to study the effect of fixed dopant on the structure and properties of CDs, three different CDs were synthesized using nicotinamide (NAA) and three common α-hydroxy acids (4–5 carbon atoms), and the optimal conditions were determined by orthogonal experimentation. Transmission electron microscopic micrographs showed that the average size of CDs based on nicotinamide are relatively large, up to 19.40 nm. X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy demonstrated that these CDs have graphite nitrogen and several functional group structures. Ultraviolet–visible absorption spectra, fluorescence emission spectra, and fluorescence lifetime illustrated that these CDs have similar emission centers (460–470 nm) and fluorescence processes. The influence of carbon source on the surface structure of CDs was determined by systematically analyzing the response of these CDs in different pH ranges. DFT calculations revealed the distribution characteristics of the electrons in the excited state at the HOMO and LUMO energy levels of CDs. All the above characterizations and calculations proved that NAA is a desirable dopant with an important contribution to the structure and properties of CDs.
研究领域:
材料科学
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化学
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DOI
PubMed
高影响因子
MOLECULES
·
2022
·Vol. 27
·期 3
·1126
·
IF 4.927
Zhong-Lei Meng,Ru-Si Wen,Xiao-Rui Huang,Rong-Xiu Qin,Yi-Ming Hu,Yong-Hong Zhou
We report the use of five alpha-hydroxy acids (citric, tartaric, mandelic, lactic and glycolic acids) as catalysts in the synthesis of terpineol from alpha-pinene. The study found that the hydration rate of pinene was slow when only catalyzed by alpha-hydroxyl acids. Ternary composite catalysts, composed of AHAs, phosphoric acid, and acetic acid, had a good catalytic performance. The reaction step was hydrolysis of the intermediate terpinyl acetate, which yielded terpineol. The optimal reaction conditions were as follows: alpha-pinene, acetic acid, water, citric acid, and phosphoric acid, at a mass ratio of 1:2.5:1:(0.1–0.05):0.05, a reaction temperature of 70 °C, and a reaction time of 12–15 h. The conversion of alpha-pinene was 96%, the content of alpha-terpineol was 46.9%, and the selectivity of alpha-terpineol was 48.1%. In addition, the catalytic performance of monolayer graphene oxide and its composite catalyst with citric acid was studied, with acetic acid used as an additive.Keywords:pinene;terpineol;alpha-hydroxy acids;phosphoric acid;synthesis
研究领域:
有机化学
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催化
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材料科学
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DOI
PubMed
高影响因子
Analytical Methods
·
2017
·Vol. 9
·期 17
·2535-2545
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IF 1.9
Jun Sang,Qun Ma,Cui-qin Li
This study was aimed at developing and validating a green HPLC-DAD method to determine anthocyanins using ethanol and an alpha-hydroxy acid aqueous solution as a mobile phase. The effects of alpha-hydroxy acids on the chromatographic behaviors of cyanidin-3-O-glucoside, the most predominant anthocyanin in nature, in a C18 column were investigated. Among seven selected alpha-hydroxy acids, tartaric acid exhibited potential for improving the chromatographic separation of cyanidin-3-O-glucoside. Cyanidin-3-O-glucoside was the main anthocyanin in haskap berry, mulberry, and blackberry, and the three berries were selected for further method development and validation. The optimized mobile phase was a mixture of ethanol and a 0.25 mol L−1 tartaric acid aqueous solution at the 20 : 80 (v/v) ratio. The retention time of cyanidin-3-O-glucoside was less than 1.8 min, and an optimum separation of anthocyanins was achieved in 4 min. The developed method was validated in terms of linearity, limits of detection and quantification, precision, repeatability, stability, and recovery. The calibration curve revealed good linearity (R2 = 0.9999), and the limits of detection and quantification were 0.038 mg L−1 and 0.125 mg L−1, respectively. The relative standard deviations of intra- and inter-day precision, repeatability, and stability were less than 5%. The recoveries of cyanidin-3-O-glucoside from the berry samples were between 99% and 101%, a satisfactory level. Additionally, the optimized mobile phase had a negligible effect on the C18 column stability. Therefore, the developed method was safe, rapid, and valid for anthocyanin analysis.
研究领域:
分析化学
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食品科学
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植物科学
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DOI
高影响因子
JOURNAL OF SEPARATION SCIENCE
·
2024
·Vol. 47
·期 3
·2300847
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IF 2.8
Xiaofei Ma,Zhenyu Fan,Zhiyuan Tang,Liangliang Cai
In this work, the potential synergetic effect between deep eutectic solvents and an antibiotic chiral selector (clindamycin phosphate) for enantioseparation was investigated in capillary electrophoresis. We synthesized a series of deep eutectic solvents with choline chloride as hydrogen bond acceptor and three α-hydroxyl acids ( l -lactic acid, l -malic acid, and l -tartaric acid) as hydrogen bond donors. Compared to the single clindamycin phosphate separation system, significantly improved separations of model drugs were observed in several synergetic systems. Compared to deep eutectic solvents with a single hydrogen bond donor, deep eutectic solvents with mixed-type hydrogen bond donors were superior. The influences of several key parameters including the type and proportion of organic modifier, clindamycin phosphate concentrations, deep eutectic solvents concentrations, and buffer pH were investigated in detail. The mechanism of the enhanced separations in deep eutectic solvents systems was investigated by means of electroosmotic flow analysis, nuclear magnetic resonance analysis, and molecular modeling. It was the first time that the synergetic systems between deep eutectic solvents and antibiotic chiral selector were established in capillary electrophoresis, and these deep eutectic solvents were demonstrated to have a good synergetic effect with clindamycin phosphate for enantioseparation.
研究领域:
分析化学
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药学
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色谱学
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DOI
PubMed
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2023
·
IF 4.7
Zhen Song,Jiahui Chen,Hao Qin,Zhiwen Qi,Kai Sundmacher
Although eutectic solvents (ESs) have received considerable attention as sustainable process fluids for various applications, discovering novel ESs remains challenging as computational methods for predicting the formation of eutectics are still scarce. In the present work, both the original and modified UNIFAC models are evaluated and extended for predicting the solid–liquid equilibria (SLE) of ES systems. The applicability of the two versions of UNIFAC models is first evaluated based on the SLE of 25 ES systems composed of only conventional components. Motivated by the good evaluation results, the SLE of 50 ES systems involving one salt component are employed to extend the UNIFAC models to include novel salt-component-related functional groups. The obtained models cover widely-reported salt components of choline/tetraalkylammonium chloride/bromide and conventional components of fatty alcohols and fatty/dicarboxylic/α-hydroxy acids. A theoretical design of novel ESs in a large scale is performed with the best-performing model extension, wherein four designed ES systems are validated experimentally.
研究领域:
化学工程
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物理化学
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材料科学
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DOI
高影响因子
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