JOURNAL OF PHYSICAL CHEMISTRY B
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2016
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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
CHEMICAL ENGINEERING SCIENCE
·
2023
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IF 4.7
Yi-Fan Xue,Jie Feng,Jin-Yao Ma,Wen-Ying Li
C–N bond breaking is a difficult but crucial step in the quinoline removal of coal-based liquids. Noble metal catalysts have higher C–N bond breaking activity, but their surface bond breaking mechanism is unclear. Atomic layer deposition creates more metal-oxide sites and generates different active species, which facilitates the mechanism study. For this reason, we used atomic layer deposition to deposit TiO 2 on the catalyst surface and suggested a more complete C–N bond breaking mechanism in this study. The particle size and pore structure of the catalyst did not change significantly after the deposition, and the hydrogen adsorption was reduced when there were too many layers deposited and the surface Pt sites were occupied to a high degree. TiO 2 is extremely susceptible to reduction to Ti 3+ under hydrogen, and can change the nature of the electron density of Pt through oxygen vacancies, creating Ti 3+ -Pt δ− sites that are prone to protonation reactions. That means, the occurrence of these protonation reactions not only easily breaks the C–N bond, but also accelerates the rate of C–N bond cleavage due to the increased H coverage on the surface of the xcTi-PtAl catalysts. And the Ti 3+ -Pt δ− sites in catalyst had a stronger adsorption effect on the nitrogen-containing compounds, which in turn lowered the energy barriers of bond cleavage. It is concluded that protonation is a necessary step before the C–N bond can be broken. The subsequent steps were showed by the DFT calculations that the nitrogen-containing compounds adsorbed on the Ti 3+ -Pt δ− sites undergo β-H fracture after the protonation reaction, with the elimination reaction cleaving the C–N bond. The xcTi-PtAl catalysts by atomic layer deposition of Ti not only improve the C–N bond breaking performance, but also improve bond breaking stability by a factor of four compared to the Pt/Al 2 O 3 catalysts.
研究领域:
催化化学
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能源化学
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表面科学
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DOI
高影响因子
Science Advances
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2025
·Vol. 11
·期 14
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IF 12.5
Cong Zhao,Kun Li,Jie Hao,Yanlei Wang,Hongyan He,Chuancheng Jia,Xuefeng Guo
Elucidating the mechanisms of ion-involved interfacial reactions at the single-bond level is important for understanding interface science. Here, the reaction between pyridine ions and protons at the solid-liquid interface is studied in situ using a single-molecule conductance measurement technique. By manipulating the interfacial electrostatic potential, an ion/metal interfacial state relying on electrostatic interactions has been discovered, comprising terminal group-hydrogen-gold in specific. The reversible interfacial protonation reaction mechanism is revealed in situ at the single-bond level based on this interfacial state. Experiment results also indicate that external forces can effectively regulate this ion-involved interfacial reaction. This work provides a single-bond approach for in situ investigations of ion-involved interfacial reactions with an ion/metal interfacial state, thus promoting the development of interface science.
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高影响因子
ANALYTICAL CHEMISTRY
·
2021
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IF 6.986
Yuchen Tang,Xuqi Chen,Shaohua Zhang,Zachary J. Smith,Tingjuan Gao
Due to the fundamental mechanism of vibrational state transitions for chemical bonds, the spectra of Raman scattering are narrow-banded and photostable signals capable of probing specific reactions. In the case of protonation/deprotonation reactions, certain chemical bonds are broken and new bonds are formed. Based on the changes of the vibrational modes for the corresponding bonds, fingerprint analysis of multiple Raman bands may allow for the in situ visualization of proton distribution in live cells. However, Raman scattering faces the well-known challenge of low sensitivity. To perform the vibrational fingerprint analysis of Raman scattering by overcoming this challenge, we developed an azo-based resonance Raman pH probe. It was an azobenzene-featured small molecule responsive to protons with the inherent Raman signal ∼104-fold more intense than that of the conventional alkyne-type Raman reporter 5-ethynyl-2′-deoxyuridine. Through the substitution of the electron-donating and -withdrawing entities to the azobenzene group, the effect of resonance Raman scattering and fluorescence quenching was obtained. This effect resulted in a significant Raman enhancement factor of ∼103 compared to the counterpart molecules without the molecular design. Based on the enhanced Raman sensitivity of the azo-based resonance Raman pH probe, the identification of vibrational fingerprint changes at the azo group was achieved during the protonation/deprotonation reactions, and the vibrational fingerprint analysis resolved a pH difference of less than 0.2 unit. The method enabled sensitive hyperspectral cell imaging that clearly visualized the change of proton distribution in autophagic cells.
研究领域:
化学
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生物物理
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细胞生物学
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光谱学
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DOI
PubMed
高影响因子
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