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Sodium zirconate (sodium zirconium oxide; Na2ZrO3) is a widely investigated carbon dioxide (CO2) sorbent. Since it was first discussed in the 1960s, Na2ZrO3 has been reported to adopt monoclinic, hexagonal, and cubic structures, and it is widely believed that the CO2 capture performance of Na2ZrO3 is related to its crystal structure. Researchers have relied on the differences in the relative intensities of two peaks (2 ∼16.2° and 38.7°) in the powder X-ray diffraction (PXRD) pattern to determine the phase of this compound. However, to date, a defined crystal structure of hexagonal Na2ZrO3 has remained elusive. Our findings show that the current literature discussion on the structure of Na2ZrO3 is misleading. With the use of 3D electron diffraction (3D ED), and PXRD, we prove that hexagonal Na2ZrO3 does not exist. The so-called hexagonal Na2ZrO3 is actually Na2ZrO3 with three different types of disorder. Furthermore, the two PXRD peaks (2 ∼16.2° and 38.7°) cannot be used to distinguish the different phases of Na2ZrO3, as the change in the PXRD pattern is related to the extent of structure disorder. Finally, we also show that the CO2 uptake properties of Na2ZrO3 are not related to the differences in crystal structures, but rather to the Na+ site occupancy differences in different Na2ZrO3 samples. In order to further develop applications of Na2ZrO3, as well as other mixed-metal oxides, their structures, and the existence of any disorder, need be understood using the methods shown in this study. [ABSTRACT FROM AUTHOR]

A direct catalytic stereoselective synthesis of C4' functionalized furanoside and nucleoside derivatives with a tetrasubstituted stereocenter is disclosed. The amine‐catalyzed stereoselective α‐aminomethylation reactions on furanoside‐derived aldehyde derivatives gave the corresponding C4' functionalized D‐ or L‐ribose derivatives in good to excellent yields (67−94%) with up to >20:1 dr. [ABSTRACT FROM AUTHOR]

The solution chemistry of aluminum is highly complex and various polyoxocations are known. Here we report on the facile synthesis of a cationic Al24 cluster that forms porous salts of composition [Al24(OH)56(CH3COO)12]X4, denoted CAU‐55‐X, with X=Cl−, Br−, I−, HSO4−. Three‐dimensional electron diffraction was employed to determine the crystal structures. Various robust and mild synthesis routes for the chloride salt [Al24(OH)56(CH3COO)12]Cl4 in water were established resulting in high yields (>95 %, 215 g per batch) within minutes. Specific surface areas and H2O capacities with maximum values of up to 930 m2 g−1 and 430 mg g−1 are observed. The particle size of CAU‐55‐X can be tuned between 140 nm and 1250 nm, permitting its synthesis as stable dispersions or as highly crystalline powders. The positive surface charge of the particles, allow fast and effective adsorption of anionic dye molecules and adsorption of poly‐ and perfluoroalkyl substances (PFAS). [ABSTRACT FROM AUTHOR]

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We report an efficient radical‐mediated C−C coupling through photoredox‐catalyzed reactions of 4‐alkyl‐dihydropyridines (DHPs) and vinylbenziodoxol(on)es (VBX, VBO). This transition‐metal‐free and mild photocatalytic method has excellent functional group tolerance and affords vinylated products in good yields, with complete retention of the alkene configuration. The utility of the methodology is demonstrated by the diastereoselective synthesis of C‐vinyl glycosides. Preliminary mechanistic studies suggest that the C−C bond formation is stereospecific and proceeds through a concerted radical coupling transition state. [ABSTRACT FROM AUTHOR]

The CO2 sorption properties of sodium hafnium oxide (Na2HfO3) were investigated in this study. Na2HfO3 was synthesized by solid-state synthesis using Na2CO3 and HfO2 as starting materials. The solid-state synthesized Na2HfO3 appeared structurally similar to other mixed metal oxides such as Na2ZrO3, but stacking disorder appeared to be common in Na2HfO3. The synthesis conditions, including the Na : Hf ratio (between 0.5 and 1.5 : 1), synthesis temperature, time and heating rate, were investigated to optimize CO2 sorption properties of Na2HfO3. The Na2HfO3 sorbent showed comparable CO2 uptake capacity, reaction rate and excellent cycling stability compared to other metal oxide sorbents. Na2HfO3 with Na : Hf = 1 : 1 and 1.25 : 1 showed the highest CO2 uptake among all Na2HfO3 samples obtained, with a CO2 uptake capacity of around 15 wt% (at 650–800 °C). The CO2 uptake rate of NHO-1 and NHO-1.25 was fast with over 80% of the equilibrium uptake reached within 250 s. Na2HfO3 remained stable even after 100 cycles with less than 3% difference in the CO2 uptake capacity between the 1st and 100th cycles. We performed kinetic analysis on the CO2 sorption data and found that the Avrami–Erofeev model fitted the kinetic data best among the kinetic models used. Apart from sorbent optimization, we showed that 3D-printing of Na2HfO3 : HfO2 mixtures can be used to produce structured Na2HfO3 sorbents with a slightly improved CO2 uptake rate and the same CO2 uptake capacity as the powder-based solid-state synthesized Na2HfO3 sorbent. [ABSTRACT FROM AUTHOR]