Enhancement of CO2 adsorption and separation in basic ionic liquid/ZIF-8 with core-shell structure.

A novel strategy was proposed to improve the performance of gas separation in nano-materials, by fabricating a core-shell structure out of the basic ionic liquid ([Emim]2[IDA]) and zeolitic imidazolate framework (ZIF-8). The [Emim]2[IDA]/ZIF-8 exhibits a remarkable CO2 adsorption capacity of 14 cm3 g-1 at 298 K and 20 kPa, the ideal selectivity of CO2/N2 is as high as 104 and CO2/CH4 is 348 at 298 K and 100 kPa, which are much higher than the CO2 adsorption capacity (4.3 cm3 g-1) and the selectivity (SCO2/N2 = 7.4, SCO2/CH4 = 2.7) of ZIF-8. This work could pave the way for designing advanced nanostructures tailored for gas separation.

Microenvironment Modulation of Single-Atom Ru in ZrSBA-15 for CO2 Hydrogenation to Formic Acid.

The chemical microenvironment modulation of active sites holds promise for facilitating their catalytic performance. Herein, single-atom Ru anchored by ZrSBA-15 modified with diverse organic amine groups has been fabricated and enabled CO2 hydrogenation to produce formic acid (FA) under mild conditions. However, the reaction cannot be achieved without the modification of organic amines. The functional groups as the microenvironment around Ru active sites effectively regulated the activity, in which Ru encapsulated in ZrSBA-15 bearing -NH2 groups exhibited the highest activity, with turnover number (TON) and turnover frequency (TOF) values of 505 and 64 h-1, respectively. Both characterization and experimental results validated that the functional group manipulated the adsorption capacity of the reactant, the electronic state of Ru and hydrophilicity/hydrophobicity of the materials, and thus the catalytic performance.

Silver Ions Drive Ordered Self-Assembly Mechanisms and Inherent Properties of Lignin Nanoflowers.

Designing anisotropic lignin-based particles and promoting the high-value utilization of lignin have nowadays drawn much attention from scientists. However, systematic studies addressing the self-assembly mechanisms of anisotropic lignin-based particles are scarce. In this work, an interaction including the electrostatic forces and chelating forces between lignin and Ag+ was regulated via carboxymethylation modification. Subsequently, the aggregation morphology of carboxymethylated lignin in a Ag+ solution was observed via SEM. The result showed that a large number of Ag+ intercalated into the lignin molecules when the grafting degree of the carboxyl groups increased from 0.17 mmol/g to 0.53 mmol/g, which caused the lignin molecules to gradually transform from disordered blocks to ordered layers. Dynamics research indicated that the adsorption process of Ag+ in carboxymethylated lignin conforms to the Pseudo-first-order kinetic model. The saturated adsorption amount of Ag+ in the carboxymethylated lignin reached 1981.7 mg/g when the grafting rate of carboxyl groups increased to 0.53 mmol/g, which then fully intercalated into lignin molecules and formed a layered structure. The thermodynamic parameters showed that the thermal adsorption process conforms to the Langmuir model, which indicates that Ag+ is monolayer-adsorbed and intercalated into lignin molecules. Meanwhile, the ΔH values are more than 0, which suggests that this adsorption process is a endothermic reaction and that a higher temperature is conducive to an adsorption reaction. Therefore, self-assembly of lignin in a Ag+ solution under 70 °C is more conducive to the formation of a nanoflower structure, which is consistent with our experimental result. Finally, pH-responsive Pickering emulsions were successfully prepared using a lignin-based nanoflowers, which demonstrated their potential as a catalytic platform in the interface catalysis field. This work offers a deeper understanding into the formation mechanism of anisotropic lignin-based nanoflowers and hopes to be helpful for designing and preparing anisotropic lignin-based particles.

Synthesis, Spectroscopic Characterization, Crystal Structures and Antibacterial Activity of Vanadium(V) Complexes of Fluoro- and Chloro-Substituted Benzohydrazone Ligands.

A new vanadium(V) complex, [VOL(OMe)(MeOH)]·MeOH (1·MeOH), was prepared by the reaction of VO(acac)2 with 2-chloro-N'-(5-fluoro-2-hydroxybenzylidene)benzohydrazide (H2L) in methanol. By addition of salicylhydroxamic acid (HSHA) to the methanolic solution of 1, a new salicylhydroxamate-coordinated vanadium(V) complex, [VOL(SHA)]·H2O (2·H2O), was obtained. Both complexes were characterized by elemental analysis, infrared spectroscopy, thermal analysis and single crystal X-ray diffraction. Complex 1 crystallizes with methanol molecule as a solvate, and complex 2 as a monohydrate. The V atoms in the complexes are in octahedral coordination. In the crystal structure of 1·MeOH, the vanadium complexes are linked by methanol solvate molecules through intermolecular O-H∙∙∙N and O-H∙∙∙O hydrogen bonds to form chains along the c axis. In the crystal structure of 2·H2O, the vanadium complexes are linked by water molecules through intermolecular O-H∙∙∙O hydrogen bonds, to form 1D chains along the a axis. The chains are further linked through intermolecular O-H∙∙∙N and O-H∙∙∙O hydrogen bonds in the c direction to form 2D layers. The antimicrobial activities of the complexes against K. pneumoniae, S. aureus, P. aeroginosa, E. coli, and B. subtilis were investigated.