NMR Insights on the Properties of ZnCl₂ Molten Salt Hydrate Medium through Its Interaction with SnCl₄ and Fructose

The solvent properties of ZnCl₂ molten salt medium and its synergic effect with the Lewis acid catalyst, Sn⁴⁺, for biomass conversion, were investigated by nuclear magnetic resonance. The tautomeric distribution of fructose in the ZnCl₂ molten salt medium was examined, and its effect for humins formation during the biomass conversion was evaluated. The ion complex composed by Sn⁴⁺ and Zn²⁺ indicated that there is a synergic catalytic effect between these two Lewis acid ions. ¹³C NMR spectra of fructose in different ZnCl₂ molten salt hydrate concentrations revealed that the concentration of β-furanose and α-furanose tautomers, which lead to 5-HMF, were significantly decreased with increased salt concentration. Meanwhile the β-pyranose tautomer, which is correlated with humins formation, was increased significantly

A crystalline bisindolylmaleimide with strong solid-state fluorescence of red color and its analogous cross-linked polymer without fluorescence

<p>A crystalline bisindolylmaleimide (BIM) <b>3</b> with strong fluorescence in the solid state was prepared and studied. Its analogous cross-linked polymer <b>4</b> with the same BIMs fluorophore was designed and characterized. The investigation of the covalent bonding networking effect on the solid-state fluorescence was carried out by the comparison between <b>3</b> and <b>4</b>.</p

Cobalt Nanocluster Supported on ZrRE_<i>n</i>O_<i>x</i> for the Selective Hydrogenation of Biomass Derived Aromatic Aldehydes and Ketones in Water

In this study, rare earth (RE) metal doped ZrO₂ was prepared by a surfactant-assisted coprecipitation/hydrothermal crystallization method and used to load Co as catalyst for the hydrogenation of aromatic carbonyl compounds in water. Furfural was hydrogenated to furfural alcohol in water with up to 95 mol % yield over Co/ZrLa_0.2O_<i>x</i> at 40 °C, 2 MPa H₂ in 10 h. The doping of rare earth metal oxide has three advantages: (I) it promotes the ZrO₂ to reach a small-sized, stable, and high-activity tetragonal phase zirconia and thus lead to a high specific surface area for metal loading; (II) it interacts with Co to reach an ultrasmall average particle size of 1.1 nm; and (III) it modifies the ZrO₂ surface to increase the amount of acidic sites for the adsorption of carbonyl feedstock. The adsorption experiment indicated a tight interaction between not only the carrier and CO bond but also the Co clusters and CO bond, which were of benefit for the hydrogenation of carbonyl groups. The surfactant addition during the carrier preparation improves the strong metal–support interactions (SMSI) to promote Co dispersion and stability. Various rare earth metals including La, Pr, Nd, and Ce could modify ZrO₂ with a similar mechanism. The as-prepared Co catalyst could also catalyze the selective hydrogenation of various aromatic aldehydes and ketones (such as 5-hydroxymethyl furfural, benzaldehyde, and acetophenone) in water, and 100% yield to corresponding alcohols was achieved. The catalyst remained stable and showed little deactivation during the recycling tests. This study not only presented a high-efficient, low-cost, and stable catalyst for the selective hydrogenation of various aromatic aldehydes and ketones but also give rise to an understanding of rare earth metal oxide doped ZrO₂ supported nano Co ternary catalysts

Different subtypes of gestational diabetes mellitus are associated with distinct perinatal outcomes in twin pregnancies

Aims To determine whether different gestational diabetes mellitus (GDM) subtypes are associated with distinct perinatal outcomes in twin pregnancies. Materials This retrospective cohort study enrolled women with twin pregnancies who gave birth at a tertiary hospital between January 2017 and December 2022. GDM was diagnosed by the IADPSG diagnostic criteria. Three subtypes of GDM were defined as only abnormal fasting glucose (OAFG) values, only abnormal post-load glucose (OAPG) values and abnormal combined fasting and post-load glucose (ACFPG) values. Logistic regression or generalized estimation equation models were used to test the correlation of subtypes of GDM and perinatal outcomes. Results GDM with OAPG had a slightly higher risk for preterm delivery (PTD) at Conclusions Different subtypes of GDM are associated with distinct perinatal outcomes. Only abnormal fasting glucose levels may be responsible for reduced the risk of SGA neonates.</p

DOSY NMR: A Versatile Analytical Chromatographic Tool for Lignocellulosic Biomass Conversion

The diffusion ordered NMR spectroscopy (DOSY) protocol for the analysis of reaction mixture of lignocellulosic biomass conversion has been developed and investigated systematically. Model reaction mixtures from cellulose, hemicellulose and lignin conversion, real reaction mixtures of sucrose and glucose dehydration, were facilely separated and assigned in the diffusion dimension without any prior separation or isolation. The shift reagent, EuFOD, was successfully utilized to increase the difference in diffusion and thereby resolution in lignin degradation model. DOSY NMR offers an easy and robust method for the structure identification and reaction mixture separation in biomass conversion

Insight into the Mechanism of Water-Promoted Hydrogenation of Maleic Acid to Succinic Acid on Pd/C Catalyst

Solvent provides additional degrees of freedom to regulate catalyst reactivity in liquid-phase heterogeneous catalysis, but it is still a challenge to have insight into the multifaceted solvent effects. Herein, a remarkable promotional effect of water in maleic acid (MAc) hydrogenation to succinic acid (SAc) was observed. Kinetic studies showed that the apparent activation energy in water was much lower than in organic solvents. A series of isotope-labeling experiments were designed, and the products were analyzed by NMR (1H, 13C, 2H, and DEPT135 spectra). The results showed that D2O participated in MAc CC hydrogenation and 34.7% of SAc was deuterated. The structures of these deuterated compounds were further confirmed by electrospray mass spectrometry (ESI-MS). The detailed mechanism of water participating in MAc CC hydrogenation was studied by quasi-in situ mass spectrometry experiments. The results showed that H2 exchanged with D2O and formed the HD2O* transition state over the active site of Pd. Quantitative 13C NMR demonstrated that 46.2% of SAc was generated through the HD2O* transition state pathway. Based on these results, a rational mechanism of MAc hydrogenation in aqueous solution was proposed. Finally, a recyclability experiment showed that Pd/C had much better stability in water than in organic solvents

Efficient C–C Bond Formation between Two Levulinic Acid Molecules To Produce C₁₀ Compounds with the Cooperation Effect of Lewis and Brønsted Acids

An original route for levulinic acid (LA) conversion was achieved via C–C bond formation in a co-catalysis system containing Lewis and Brønsted acids. Different from conventional base-catalyzed processes, this acidic reaction system inhibits the carboxylic acid from deactivating the base catalyst, additionally simplifies the technical processes. The synergistic effect of the two types of acids effeciently catalyzed the dimerization reaction of LA to generate two C₁₀ compounds, tetrahydro-2-methyl-5,γ-dioxo-2-furanpentanoic acid and 3-(2-methyl-5-oxo-tetrahydrofuran-2-yl)-4-oxopentanoic acid, with the total yield of 50.9% at 59.7% conversion. These products present high added value as fuel or fine chemical precursors

DOSY Plus Selective TOCSY: An Efficient NMR Combination for Analyzing Hydrogenation/Hydrogenolysis Mixtures of Biomass-Derived Platform Compounds

Analyzing the mixtures obtained from hydrogenation or hydrogenolysis reactions of biomass-derived platform chemicals is challenging work. With the development and improvement of NMR techniques, the NMR spectrometer proves to be an alternative and highly efficient piece of equipment for the rapid analysis of complex mixtures without the need for tedious purification. Herein, diffusion-ordered spectroscopy (DOSY) is applied in analyzing four model mixtures, which consist of the reactants and products from hydrogenation/hydrogenolysis reactions of biomass-derived platform chemicals. The results show that the DOSY technique can pseudoseparate most components in the model mixtures. The 1D selective gradient TOCSY technique is used as a supporting tool in the cases where the DOSY technique cannot clearly distinguish between the components of the mixtures. This is generally a problem when components in the mixture have very similar diffusion coefficients or severe overlap of peaks. The results show that DOSY and 1D selective gradient TOCSY techniques make a strong combination for complex mixture analyses

Effect of mmu-miR-141 inhibitor on cell cycle.

<p>Endometrial stromal cells transfected with mmu-miR-141 inhibitor exhibited S phase arrest, while G1 and G2 phases in these cells remained unaltered. (A) normal endometrial stromal cells. (B) negative control. (C) miR-141inhibitor.</p

Primers used for Real-time RT-PCR.

<p>Primers used for Real-time RT-PCR.</p