Benzothiadiazolyl‐pyridine and ‐2,2′‐bipyridine Ligands for Luminescent and Magnetic Complexes

Posted on 12 October 2023 by nNataliya Plyuta, nThomas Cauchy, nMiguel Julve, nNarcis Avarvarin

Luminescent zinc(II) and paramagnetic copper(II) and manganese(II) complexes have been prepared with unprecedented benzothiadiazolyl−pyridine and −2,2′-bipyridine ligands.

Abstract

Two new luminescent ligands, 4-(2-pyridine)-7-methyl-2,1,3-benzothiadiazole (L¹) and 4-(2,2-bipyridine)-7-methyl-2,1,3-benzothiadiazole (L²), based on 2,1,3-benzothiadiazole and pyridine or bipyridine were obtained by Suzuki coupling reactions. DFT and TD-DFT type calculations have been performed on L¹ and L² in order to assign their experimental UV-visible and emission bands. Reaction of L¹ and L² with metal(II) chlorides (M=Zn, Mn, Cu) provided the neutral complexes of formulas [ZnL¹Cl₂] (1), [Zn(L¹)₂Cl₂] (2), [ZnL²Cl₂] (3), [MnL²Cl₂] ⋅ 0,5CH₂Cl₂ (4) and [CuL²Cl₂] ⋅ H₂O (5) which have been structurally characterized. The Zn(II) ions in 1 and 2 are four-coordinate in somewhat distorted tetrahedral N₂Cl₂ surroundings with L¹ adopting bidentate (1) and monodentate (2) coordination modes. Complexes 3–5 are isostructural and their metal atoms are five-coordinate in distorted square pyramidal environments with three nitrogen atoms from the tridentate L² ligand and a chlorine building the basal plane and another chlorine atom occupying the apical position. The three Zn(II) complexes are strongly luminescent in solution and the solid state, while the cryomagnetic study of the paramagnetic compounds 4 and 5 in the temperature range 2.9–300 K shows a Curie-Weiss behaviour typical of small antiferromagnetic interactions which are mediated by weak intermolecular contacts.

Electrochemical Synthesis of Phenothiazinone as Fluorophore and Its Application in Bioimaging

Posted on 12 October 2023 by

Electrochemical synthesis of phenothiazinone via oxidative cyclocondensation of quinone and 2-aminothiophenol under mild condition is presented, along with its bio-application as fluorophore for lipid droplets imaging in living cells.

Abstract

Phenothiazinone is a promising yet underutilized fluorophore, possibly due to the lack of a general accessibility. This study reports a robust and scalable TEMPO-mediated electrochemical method to access a variety of phenothiazinones from 2-aminothiophenols and quinones. The electrosynthesis proceeds in a simple cell architecture under mild condition, and notably carbon–halogen bond in quinones remains compared to conventional methods, enabling orthogonal downstream functionalization. Mechanistic studies corroborate that TEMPO exerts a protective effect in avoiding product decomposition at the cathode. In particular, benzophenothiazinones show intriguing luminescence in both solid and solution state, and thus their photophysical properties are scrutinized in detail. Further bio-imaging of the lipid droplets in living cells highlights the considerable promise of benzophenothiazinones as fluorescent dye in the biomedical fields.

Photo/electrocatalytic Reduction of CO2 to C2+ Products on MOF‐Based Catalysts

Posted on 12 October 2023 by nFan Guo, nYe‐Fan Zhao, nRui‐Xia Li, nHuan Xu, nWei‐Yin Sunn

Photo/electrocatalytic reduction of CO₂ to C2+ products is one of the most promising approaches for simultaneously mitigating the greenhouse gases CO₂ emission and producing value-added fuels. In this review, we present an overview of the latest advances of photo/electrocatalytic CO₂ reduction to C2+ products with focus on the catalytic performance depending on rational design of desired MOF-based catalysts.

Abstract

Efficient conversion of CO₂ to valuable fuels is a desired approach to reduce global warming effect and remit sustained fossil fuel demand. Metal–organic frameworks (MOFs), a class of crystalline porous materials with unique features, have been widely studied for potential applications in varied fields. Recently, photo/electrocatalytic reduction of CO₂ to two or more carbons (C2+) products has attracted extensive attention because of their higher market values than one carbon (C1). However, the major products of CO₂ reduction currently are carbon monoxide, formate, or methane, which are all typical C1 products. Generally, for photocatalytic reduction of CO₂ system, relatively low efficiency of electron transfer with inadequate capability results sluggish kinetics of C−C coupling. And for electrocatalysis, high current densities curtail the stability, which limits selectivity towards C2+ products. In this review, we provide very latest reports that have make some breakthroughs to overcome the above difficulties in photo/electrocatalytic reduction of CO₂ to C2+ products using MOF-based materials. Special emphases are given on design strategies of synthetic MOF-based catalysts and the mechanisms of catalytic CO₂ to C2+ products. The challenges and prospects of photo/electrocatalytic reduction of CO₂ to C2+ products associated with MOF-based materials are also discussed.

Preparation of Palladium‐Doped Nickel Phosphide Nanoparticles as Efficient Electrocatalysts for Alkaline Hydrogen Evolution Reaction

Posted on 12 October 2023 by

Colloidal, atomically dispersed Pd-doped Ni₂P nanoparticles were prepared. The Pd dopant regulates the electronic structure of Ni₂P NPs and provides an efficient active site for hydrogen production, which exhibits efficient water splitting.

Abstract

Hydrogen production through electrochemical water splitting has gained significant attention owing to its environmental benefits over traditional methods. However, designing an efficient electrocatalyst for the hydrogen evolution reaction (HER) in an alkaline electrolyte remains a significant challenge. In this study, colloidal Pd-doped Ni₂P nanoparticles were prepared via a thermal decomposition-based strategy and used as electrocatalysts for the hydrogen evolution reaction. The Pd dopant is atomically dispersed within the Ni₂P nanoparticles, regulating their electronic structure and providing an efficient active site for hydrogen production. The Pd-doped Ni₂P nanoparticles exhibited excellent electrocatalytic performance with an overpotential of 77 mV at 10 mA cm⁻² in an alkaline electrolyte and a small Tafel slope of 46 mV dec⁻¹.

A Hydrophobic Deep Eutectic Solvent for Nuclear Fuel Cycle: Extraction of Actinides and Dissolution of Uranium Oxide

Posted on 12 October 2023 by nJayashree Gamare, nBal Govind Vatsn

A hydrophobic DES having low density and viscosity based on Thenoyl trifluroacetone (HTTA) and Trioctyl phosphine oxide (TOPO) was shown to extract and partition actinides and lanthanides and used as a medium for dissolution of uranium oxide.

Abstract

Hydrophobic Deep Eutectic Solvents (DESs) have been attracting attention for metal ion extraction in solvent extraction process due to their favorable properties. A Trioctyl phosphine oxide (TOPO) and Thenoyl trifluoroacetone (HTTA) based hydrophobic DES was synthesized and characterized by FTIR and NMR spectroscopy. Actinide ions ( UO₂ ²⁺, Pu⁴⁺ and Am³⁺) and Eu³⁺ ion extraction was carried out using the DES which shows that it extracts these metal ions from aqueous nitric acid medium depending upon the molarity of nitric acid. At higher molarity of nitric acid (>5 M) the extraction becomes insignificant only for trivalent metal ions and open up the possibility to selectively strip trivalent metal ions from tetravalent and hexavalent ions. This DES was also used for dissolution of uranium oxide (UO₃). The dissolution kinetics was studied and it was shown that oxide was dissolved within an hour at 80 °C. The maximum solubility of UO₃ in DES was measured and found to be 130±5 mg/mL which is one of the highest reported solubility of UO₃ in ILs and DES. The species of uranium which is formed in situ in DES was ascertained to be UO₂(TTA)₂.TOPO after dissolution of UO₃ as supported by FTIR and NMR (¹H and ³¹P) investigations.

Dispersing LiCl in Zwitterionic COF for Highly Efficient Ammonia Storage and Separation

Posted on 12 October 2023 by

A zwitterionic covalent organic frameworks (COF) is proposed as a porous hosts to disperse LiCl for highly efficient NH₃ storage and separation. The anionic and cationic groups in zwitterionic COF act as two separated positive and negative charged sites to facilitate the dispersion of lithium chloride, which makes LiCl doped zwitterionic COF exhibit excellent NH₃ capture performance.

Abstract

Efficient and inherently safe NH₃ storage and separation are of significant importance for the chemical industry. Herein, we proposed zwitterionic COF as a porous host to disperse LiCl for highly efficient NH₃ storage and separation with record adsorption capacity. The equivalently cationic and anionic groups in the channels of zwitterionic COF could act as two separated sites to facilitate the dispersion of LiCl, hence the optimal composite exhibits a high capture capacity of 44.98 mmol/g at 25 °C and 1 bar, far exceeding other existing porous materials. Notably, the adsorption capacity is completely reversible and the efficient separation of NH₃ from NH₃/CO₂/N₂ mixture is achieved through breakthrough experiments. DFT calculation combined with XPS and ⁷Li NMR experimental results give insight into the interaction between zwitterionic COF and LiCl. This work extends possibilities for the development of efficient adsorbents for NH₃ storage and separation.

In‐Situ Growth of Cu2S‐MoS2 Bimetallic Electrocatalyst on Carbon Cloth for Hydrogen Evolution Reaction

Posted on 12 October 2023 by

Hydrogen evolution reaction (HER) is one of prospective methods to produce hydrogen energy, and the key technology of which lies in the preparation of electrocatalysts. Preparations of catalysts with high efficiency, low price and good stability are expected. In this work, a new polyoxometalate-based copper-organic framework, [{CuII(C10N6H7)4(H2O)2}H6(PMo12O40)2]·12H2O (1) [C10N6H7: 3-(1H-pyrazol-4-yl)-5-(pyridin-4-yl)-1,2,4triazole], was synthesized as an electrocatalyst precursor, and confirmed by infrared spectroscopy (IR), single-crystal X-ray diffraction (SXRD) and X-ray powder diffraction (PXRD). A newelectrocatalyst (Cu2S-MoS2@CC-1) was synthesized from 1, thiourea (TU) and carbon cloth (CC) by a one-pot hydrothermal method. Tue to the synergistic effects between Cu2S and MoS2, the Cu2S-MoS2@CC-1 catalyst exhibits high electrocatalytic HER activity and goodstability in 0.5 M H2SO4. Namely, Cu2S-MoS2@CC-1 shows low overpotential of 150 mV@10 mA·cm-2 vs reversible hydrogen electrode (RHE) and small Tafel slope of 61 mV dec-1, and remains good stability at least 94 h and over 1000 catalytic cycles. This method provides a promising strategy for development of non-noble metal catalysts.

High Mannose Oligosaccharide Hemimimetics that Recapitulate the Conformation and Binding Mode to Concanavalin A, DC‐SIGN and Langerin

Posted on 12 October 2023 by

The "carbohydrate chemical mimicry" exhibited by sp2-iminosugars has been utilized to develop practical syntheses for analogs of the branched high-mannose-type oligosaccharides (HMOs) Man3 and Man5. In these compounds, the terminal nonreducing Man residues have been substituted with 5,6-oxomethylydenemannonojirimycin (OMJ) motifs. The resulting oligomannoside hemimimetic accurately reproduce the structure, configuration, and conformational behavior of the original mannoligosaccharides, as confirmed by NMR and computational techniques. Binding studies with mannose binding lectins, including concanavalin A, DC-SIGN, and langerin, by enzyme-linked lectin assay and surface plasmon resonance revealed significant variations in their ability to accommodate the OMJ unit in the mannose binding site. Intriguingly, OMJMan segments demonstrated "in line" heteromultivalent effects during binding to the three lectins. Similar to the mannobiose (Man2) branches in HMOs, the binding modes involving the external or internal monosaccharide unit at the carbohydrate binding domain exist in equilibrium, facilitating sliding and recapture processes. This equilibrium, which influences the multivalent binding of HMOs, can be finely modulated upon incorporation of the OMJ sp2-iminosugar caps. As a proof of concept, the affinity and selectivity towards DC-SIGN and langerin were adjustable by presenting the OMJMan epitope in platforms with diverse architectures and valencies.

Preparation of Mono and Bis‐Hydrazino‐Substituted N‐Heterocyclic Carbene Boranes

Posted on 12 October 2023 by

We report the formation of NHC complexes of mono- and bis-hydrazino boranes with N–N–B and N–N–B–N–N chains via the reaction of NHC-boranes with electrophilic azo reagents. The influence of steric hindrance on the carbene and on the azo reagent has been shown to be crucial for the reactivity. The hydroboration of dissymmetric azo reagents is regioselective only when the latter is sufficiently electronically twisted. Bis-hydrazino borane complexes with two different hydrazine arms could be obtained via sequential addition.

Biological properties of cyclitols and their derivatives

Posted on 12 October 2023 by nNermin Şimşek Kuşn

Cyclitols are polyhydroxy cycloalkanes, each containing at least three hydroxyls attached to a different ring carbon atom, and its general formula is CnH2n-x(OH)x or CnH2nOx. The most important cyclitol derivatives are inositols, quersitols, conduritols and pinitols, which form a group of naturally occurring polyhydric alcohols and are widely found in plants. In addition, synthetic production of cyclitols has gained importance in recent years. Cylitols are molecules synthesized in plants as a precaution against salt or water stress. They have important functions in cell functioning as they exhibit important properties such as membrane biogenesis, ion channel physiology, signal transduction, osmoregulation, phosphate storage, cell wall formation and antioxidant activity. The biological activities of these very important molecules, obtained both synthetically and from the extraction of plants, are described in this review.