A Stable Triazole-Based Covalent Gel for Long-Term Cycling Zn Anode in Zinc-Ion Batteries

In this work, a functional covalent gel material is developed to resolve the severe dendritic growth and hydrogen evolution reaction toward Zn/electrolyte interface in aqueous zinc-ion batteries (ZIBs). A covalent gel layer with superior durability forms homogeneously on the surface of Zn foil. The covalent gel with triazole functional groups can uniformize the transport of Zn2+ due to the interactions between Zn2+ ions and the triazole groups in the covalent gel. As a consequence, the symmetrical battery with triazole covalent gel maintains stable Zn plating/stripping for over 3000 h at 1 mA cm-2 and 1 mAh cm-2 , and the full cell combined with a V2 O5 cathode operates steadily and continuously for at least 1800 cycles at 5 A g-1 with a capacity retention rate of 67.0%. This work provides a train of thought to develop stable covalent gels for the protection of zinc anode toward high-performance ZIBs.

Aggregation Modes of Chiral Diketopyrrolo[3,4-c]pyrrole Dyes in Solution and Thin Films

The chiroptical features of chiral diketopyrrolo[3,4-c]pyrrole (DPP) derivatives have been only marginally investigated to date. In this regard, we have synthesized ad hoc four chiral DPP dyes, functionalized with enantiopure alkyl groups from natural sources either on the lactam moieties or on the terminal positions of the π-conjugated backbone, to promote an efficient self-assembly into chiral supramolecular structures. For each of them, the aggregation modes has been investigated by absorbance and ECD spectroscopies in conditions of solution aggregation and on thin films, considering the effects of deposition technique (drop casting vs. spin coating) and post-deposition operations (solvent and thermal annealing). The effect of the structure of lateral π-conjugated units attached to the central DPP scaffold, as well as that of the position of the alkyl chiral group, has been assessed. ECD revealed superior capability, compared to absorbance spectroscopy, to provide information on the aggregation modes and to detect the possible co-existence of multiple aggregation pathways.

Nanofused Hierarchically Porous MIL-101(Cr) for Enhanced Methyl Orange Removal and Improved Catalytic Activity

Hierarchically porous MIL-101(Cr) (H-MIL-101(Cr)) with meso/macro-pores was directly prepared via nanofusion progress by using butyric acid as a modulating agent. In the methyl orange (MO) adsorption experiments, H-MIL-101(Cr) showed a high adsorption capability of 369.8 mg g⁻¹, which was 1.52-fold greater than that of pristine MIL-101(Cr) (P-MIL-101(Cr)). While in the oxidation reaction of indene and 1-dodecene tests, H-MIL-101(Cr) presented much higher catalytic efficiency, with turnover frequency (TOF) values of 0.7242 mmol g⁻¹ min⁻¹ and 0.1492 mmol g⁻¹ min⁻¹, respectively, which were 28% and 34% greater than that in the case of P-MIL-101(Cr). Thus, compared with P-MIL-101(Cr), H-MIL-101(Cr) exhibited better removal efficiency and higher levels of activity in the oxidation reactions of indene and 1-dodecene. The unique structure of H-MIL-101(Cr) also contributed to its superior performance in these processes.

Enhanced Degradation of Rhodamine B by Metallic Organic Frameworks Based on NH2-MIL-125(Ti) under Visible Light

Samples of the bimetallic-based NH2-MIL-125(Ti) at a ratio of Mn+/Ti4+ is 0.15 (Mn+: Ni2+, Co2+ and Fe3+) were first synthesized using the solvothermal method. Their fundamental properties were analyzed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectra, scanning electron microscopy (SEM), N2 adsorption-desorption measurements, and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). The as-acquired materials were used as high-efficiency heterogeneous photocatalysts to remove Rhodamine B (RhB) dye under visible light. The results verified that 82.4% of the RhB (3 × 10-5 M) was degraded within 120 min by 15% Fe/Ti-MOFs. Furthermore, in the purpose of degrading Rhodamine B (RhB), the rate constant for the 15% Fe/Ti-MOFs was found to be 2.6 times as fast as that of NH2-MIL-125(Ti). Moreover, the 15% Fe/Ti-MOFs photocatalysts remained stable after three consecutive cycles. The trapping test demonstrated that the major active species in the degradation of the RhB process were hydroxyl radicals (HO∙) and holes (h+).

Synthetic Methods for the Preparation of Conformationally Restricted Analogues of Nicotine

In the context of naturally occurring nitrogen heterocycles, nicotine is a chiral alkaloid present in tobacco plants, which can target and stimulate nicotinic acetylcholine receptors (nAChRs), a class of ligand-gated ion channels commonly located throughout the human brain. Due to its well-known toxicity for humans, there is considerable interest in the development of synthetic analogues; in particular, conformationally restricted analogues of nicotine have emerged as promising drug molecules for selective nAChR-targeting ligands. In the present mini-review, we will describe the synthesis of the conformationally restricted analogues of nicotine involving one or more catalytic processes. In particular, we will follow a systematic approach as a function of the heteroarene structure, considering: (a) 2,3-annulated tricyclic derivatives; (b) 3,4-annulated tricyclic derivatives; (c) tetracyclic derivatives; and (d) other polycyclic derivatives. For each of them we will also consider, when carried out, biological studies on their activity for specific nAChR subunits.

Photocatalytic Activity of Nanocoatings Based on Mixed Oxide V-TiO2 Nanoparticles with Controlled Composition and Size

V-TiO2 photocatalyst with 0 ≤ V ≤ 20 mol% was prepared via the sol–gel method based on mixed oxide titanium–vanadium nanoparticles with size and composition control. The mixed oxide vanadium–titanium oxo-alkoxy nanonoparticles were generated in a chemical micromixing reactor, coated on glass beads via liquid colloid deposition method and underwent to an appropriate thermal treatment forming crystallized nanocoatings. X-ray diffraction, Raman, thermogravimetric and differential thermal analyses confirmed anatase crystalline structure at vanadium content ≤ 10 mol%, with the cell parameters identical to those of pure TiO2. At a higher vanadium content of ~20 mol%, the material segregation began and orthorhombic phase of V2O5 appeared. The crystallization onset temperature of V-TiO2 smoothly changed with an increase in vanadium content. The best photocatalytic performance towards methylene blue decomposition in aqueous solutions under UVA and visible light illuminations was observed in V-TiO2 nanocoatings with, respectively, 2 mol% and 10 mol% vanadium.

Palladium(II) on 4 Å Molecular Sieves: A Simple and Reusable Catalyst for the Preparation of Ynones

Abstract

Pd2+ on 4 Å molecular sieves support has been prepared and investigated. The catalyst has successfully been used in the reaction of acyl chlorides and terminal alkynes yielding ynones. The catalyst can be reused without significant loss of activity.

Graphic Abstract

Preparation of Chitosan/Polyacrylamide/Graphene Oxide Composite Membranes and Study of Their Methylene Blue Adsorption Properties

This thesis reports the preparation of chitosan/polyacrylamide/graphene oxide nanocomposites (CAGs) and a study of its adsorption properties of methylene blue (MB) solution. Initially, we synthesized CAGs by blending and freeze-drying methods. Then, we conducted a series experiments by removing MB from aqueous solution to test its adsorption properties and adsorption mechanism. We used UV-Vis spectrophotometry to determine the concentration of residual methylene blue accurately and efficiently, which has a specific absorption peak at 662 nm in the UV-Vis spectrum, in aqueous solution. When the graphene oxide content in the composite was 20 wt%, the adsorption capacity reached maximum values. The chemical properties and surface structure of the nanomaterials were analyzed using FT-IR, TGA, SEM, and BET. Also, we carried out experiments to measure the adsorption properties of the CAGs by varying several factors, such as initial concentration, adsorption time, and pH, etc. The outcomes revealed that the adsorption equilibrium was developed after 2800 min at 20 °C (room temperature) with an adsorbent dosage of 0.01 g.mL-1. The ion adsorption equilibrium data were well-fitted by the Langmuir isotherm with a maximum monolayer capacity of 510.2 mg/g. Kinetic researches disclosed that the adsorption procedure was defined by a pseudo-second-order model. Thermodynamic researches revealed that the enthalpy change (ΔH0) as well as Gibbs free energy change (ΔG0) of the adsorption procedure was negative, indicating that the adsorption procedure was spontaneous and exothermic. After three cycles, the removal efficiency was still 90.18%. Therefore, in conclusion, we believe that the CAGs is a good adsorption material for organic dyes due to its good adsorption and recyclable properties.

Modified Nano-TiO2 Based Composites for Environmental Photocatalytic Applications

TiO2 probably plays the most important role in photocatalysis due to its excellent chemical and physical properties. However, the band gap of TiO2 corresponds to the Ultraviolet (UV) region, which is inactive under visible irradiation. At present, TiO2 has become activated in the visible light region by metal and nonmetal doping and the fabrication of composites. Recently, nano-TiO2 has attracted much attention due to its characteristics of larger specific surface area and more exposed surface active sites. nano-TiO2 has been obtained in many morphologies such as ultrathin nanosheets, nanotubes, and hollow nanospheres. This work focuses on the application of nano-TiO2 in efficient environmental photocatalysis such as hydrogen production, dye degradation, CO2 degradation, and nitrogen fixation, and discusses the methods to improve the activity of nano-TiO2 in the future.

Acyl Sonogashira Cross-Coupling: State of the Art and Application to the Synthesis of Heterocyclic Compounds

The acyl Sonogashira reaction represents an extension of Sonogashira cross-coupling to acid chlorides which replace aryl or vinyl halides, while terminal acetylenes are used as coupling partners in both reactions. The introduction of a carbonyl functional group on the alkyne backbone determines a radical change in the reactivity of the products. Indeed, α,β-alkynyl ketones can be easily converted into different heterocyclic compounds depending on the experimental conditions employed. Due to its potential, the acyl Sonogashira reaction has been deeply studied with particular attention to the nature of the catalysts and to the structures of both coupling compounds. Considering these two aspects, in this review, a detailed analysis of the literature data regarding the acyl Sonogashira reaction and its role in the synthesis of several heterocyclic derivatives is reported.