scholarly journals Ethanol- and Methanol-Coordinated and Solvent-Free Dodecahydro closo-Dodecaborates of 3d Transition Metals and of Magnesium

Crystals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 372 ◽  
Author(s):  
Emilie Didelot ◽  
Zbigniew Łodziana ◽  
Fabrizio Murgia ◽  
Radovan Černý
Keyword(s):  
Transition Metals ◽  
Solvent Free ◽  
Metal Oxidation ◽  
Temperature Dependent ◽  
Dynamic Vacuum ◽  
Li Ion ◽  
Solvent Molecules ◽  
Free Metal ◽  
Potential Use ◽  
Successive Removal

Magnesium and 3d transition metals closo-borates were prepared by mechanosynthesis (ball milling) of the mixtures Na2B12H12 + MCl2 (M = Mn, Fe, Co, Ni, Mg), followed by addition of ethanol or methanol and drying under dynamic vacuum. The dead mass of NaCl is partly removed by filtration. The crystal structures of solvent-coordinated and solvent-free closo-borates have been characterized by temperature dependent synchrotron radiation X-ray powder diffraction, ab initio calculations, thermal analysis and infrared spectroscopy. Various solvated complexes containing six, four, three, two or one solvent molecules were obtained by successive removal of the solvent until in most case the solvent-free metal closo-borates were obtained with the exception of Mg whose hypothetical crystal structure, however, could have its prototype in MnB12H12. The 3d transition metal closo-borates were studied in the view of their potential use as Na- or Li-ion battery electrodes in combination with Na or Li closo-borate solid electrolytes. The metal oxidation state (II) obtained in compounds presented here does not allow such application.

Temperature Dependent Green Synthesis of 3-Carboxycoumarins and 3,4-unsubstituted Coumarins

2019 ◽  
Vol 16 (1) ◽  
pp. 130-135 ◽  
Author(s):  
Jack van Schijndel ◽  
Dennis Molendijk ◽  
Luiz Alberto Canalle ◽  
Erik Theodorus Rump ◽  
Jan Meuldijk
Keyword(s):  
Knoevenagel Condensation ◽  
Ammonium Bicarbonate ◽  
Solvent Free ◽  
Temperature Dependent ◽  
Step Procedure ◽  
Synthetic Routes ◽  
High Yields ◽  
Temperature Optima ◽  
Solvent Free Synthesis ◽  
Full Conversion

Aim and Objective: Because of the low abundance of 3,4-unsubstituted coumarins in plants combined with the complex purification process required, synthetic routes towards 3,4-unsubstituted coumarins are especially valuable. In the present work, we explore the possibilities of a solvent-free Green Knoevenagel condensation on various 2-hydroxybenzaldehyde derivatives and malonic acid without the use of toxic organocatalysts like pyridine and piperidine but only use ammonium bicarbonate as the catalyst. Materials and Methods: To investigate the scope of the Green Knoevenagel condensation for the synthesis of 3,4-unsubstituted coumarins, various 2-hydroxybenzaldehyde derivatives were screened as starting material in the optimized two-step procedure developed for 2-hydroxybenzaldehyde. </P><P> Results: This study shows that the intramolecular esterification and the decarboxylation are in competition, but show different temperature optima. In order to suppress premature decarboxylation and maximize the yield of coumarin, a two-step procedure was adopted. The reaction mixture containing ammonium bicarbonate is initially kept at 90ºC for 1 hour. After completion of the cyclization, the temperature of the reaction mixture is increased to 140ºC for 2 hours. Following this protocol, coumarin could be isolated with a yield of 95%. Conclusion: A two-step procedure for the solvent-free synthesis of several 3,4-unsubstituted coumarins was developed using ammonium bicarbonate, resulting in high yields of the desired products. Moreover, this procedure has a low E-factor and is, therefore an environmental friendly reaction in line with the principles of Green Chemistry. It was shown that by initially capping the temperature at 90ºC, premature decarboxylation can be suppressed. After full conversion to the intermediate 3-carboxycoumarin, the temperature can be increased to 140ºC finalizing the reaction. Ammonium bicarbonate was shown to catalyze both the Green Knoevenagel condensation and the decarboxylation step.

Optimized electron occupancy of solid-solution transition metals for suppressing the oxygen evolution of Li2MnO3

2021 ◽  
Vol 9 (14) ◽  
pp. 9337-9346
Author(s):  
Erhong Song ◽  
Yifan Hu ◽  
Ruguang Ma ◽  
Yining Li ◽  
Xiaolin Zhao ◽  
...  
Keyword(s):  
Solid Solution ◽  
Energy Density ◽  
Transition Metals ◽  
Oxygen Evolution ◽  
High Energy ◽  
High Energy Density ◽  
Li Ion Batteries ◽  
Li Ion ◽  
Increasing Demand ◽  
Layered Cathodes

Li-rich layered cathodes based on Li2MnO3 have exhibited extraordinary promise to satisfy the rapidly increasing demand for high-energy density Li-ion batteries.

REACTION OF SOME SALICYL ALDEHYDE DERIVATIVES WITH AMINES ANDPHENYL ACETYLENE

2020 ◽  
Vol 65 (10) ◽  
pp. 61-66
Author(s):  
Trang Nguyen Thi Minh ◽  
Trang Tran Thi Thu ◽  
Hoan Duong Quoc
Keyword(s):  
Coupling Reaction ◽  
Solvent Free ◽  
Metal Free ◽  
Phenyl Acetylene ◽  
A3 Coupling ◽  
Free Metal

Salicylic aldehydes, amine, and phenyl acetylene could react under the solvent-free, metal-free conditions to form propargylamines 1-4 via A3 coupling reaction. The yield of the reaction was up to 83% for 5h. In acetonitrile, the amine became a catalyst to form 6-bromo-3-(5-bromo-2-hydroxybenzyl)-2-phenyl-4Hchromen-4-one (5). Under microwave conditions, it took about 20 min to complete the reaction and gave the same yields as theconventional method. Structures of these compounds were firm with NMR, MS spectra.

scholarly journals Solvent-Free and Scalable Procedure to Prepare PYR13TFSI/LiTFSI/PVDF–HFP Thermoplastic Electrolytes with Controlled Phase Separation and Enhanced Li Ion Diffusion

Membranes ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 50 ◽  
Author(s):  
Víctor Gregorio ◽  
Nuria García ◽  
Pilar Tiemblo
Keyword(s):  
Ionic Conductivity ◽  
Polyvinylidene Fluoride ◽  
Ionic Conductivities ◽  
Single Step ◽  
Solvent Free ◽  
High Concentration ◽  
Scanning Calorimetry ◽  
Melt Compounding ◽  
Li Ion ◽  
Pfg Nmr

Solid electrolytes for Li transport have been prepared by melt-compounding in one single step. Electrolytes are composed of polyvinylidene fluoride–hexafluoropropylene (PVDF–HFP) with PYR13TFSI on its own or with varying concentration of LiTFSI. While the extrusion of PVDF–HFP with PYR13TFSI is possible up to relatively high liquid fractions, the compatibility of PVDF–HFP with LiTFSI/PYR13TFSI solutions is much lower. An organo-modified sepiolite with D-α-tocopherol polyethylene glycol 1000 succinate (TPGS-S) can be used to enhance the compatibility of these blends and allows to prepare homogeneous PYR13TFSI/LiTFSI/PVDF–HFP electrolytes with controlled microphase separations by melt-compounding. The structure and morphology of the electrolytes has been studied by FTIR, differential scanning calorimetry (DSC), SEM, and AFM. Their mechanical properties have been studied by classical strain–stress experiments. Finally, ionic conductivity has been studied in the −50 to 90 °C temperature range and in diffusivity at 25 °C by PFG-NMR. These electrolytes prove to have a microphase-separated morphology and ionic conductivity which depends mainly on their composition, and a mechanical behavior typical of common thermoplastic polymers, which makes them very easy to handle. Then, in this solvent-free and scalable fashion, it is possible to prepare electrolytes like those prepared by solvent casting, but in few minutes instead of several hours or days, without solvent evaporation steps, and with ionic conductivities, which are very similar for the same compositions, above 0.1 mS·cm−1 at 25 °C. In addition, some of the electrolytes have been prepared with high concentration of Li ion, what has allowed the anion exchange Li transport mechanism to contribute significantly to the overall Li diffusivity, making DLi become similar and even clearly greater than DTFSI.

Processing and characterization of titanium dioxide grown on titanium foam for potential use as Li-ion electrode

2017 ◽  
Vol 411 ◽  
pp. 363-367 ◽  
Author(s):  
Hyelim Choi ◽  
Hyeji Park ◽  
Ji Hyun Um ◽  
Won-Sub Yoon ◽  
Heeman Choe
Keyword(s):  
Titanium Dioxide ◽  
Li Ion ◽  
Titanium Foam ◽  
Potential Use

scholarly journals Understanding the Mechanisms Underlying Host Restriction of Insect-Specific Viruses

Viruses ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 964 ◽  
Author(s):  
Ahmed ME Elrefaey ◽  
Rana Abdelnabi ◽  
Ana Lucia Rosales Rosas ◽  
Lanjiao Wang ◽  
Sanjay Basu ◽  
...  
Keyword(s):  
Structural Genes ◽  
Restriction Factors ◽  
Temperature Dependent ◽  
Complex Interplay ◽  
Mortality And Morbidity ◽  
Host Restriction ◽  
The Past ◽  
Vertebrate Hosts ◽  
Potential Use ◽  
Hematophagous Arthropod

Arthropod-borne viruses contribute significantly to global mortality and morbidity in humans and animals. These viruses are mainly transmitted between susceptible vertebrate hosts by hematophagous arthropod vectors, especially mosquitoes. Recently, there has been substantial attention for a novel group of viruses, referred to as insect-specific viruses (ISVs) which are exclusively maintained in mosquito populations. Recent discoveries of novel insect-specific viruses over the past years generated a great interest not only in their potential use as vaccine and diagnostic platforms but also as novel biological control agents due to their ability to modulate arbovirus transmission. While arboviruses infect both vertebrate and invertebrate hosts, the replication of insect-specific viruses is restricted in vertebrates at multiple stages of virus replication. The vertebrate restriction factors include the genetic elements of ISVs (structural and non-structural genes and the untranslated terminal regions), vertebrate host factors (agonists and antagonists), and the temperature-dependent microenvironment. A better understanding of these bottlenecks is thus warranted. In this review, we explore these factors and the complex interplay between ISVs and their hosts contributing to this host restriction phenomenon.

Fundamental insights about interlayer cation migration in Li-ion electrodes at high states of charge

2019 ◽  
Vol 7 (19) ◽  
pp. 11996-12007 ◽  
Author(s):  
Julija Vinckevičiūtė ◽  
Maxwell D. Radin ◽  
Nicholas V. Faenza ◽  
Glenn G. Amatucci ◽  
Anton Van der Ven
Keyword(s):  
Transition Metals ◽  
Interlayer Cation ◽  
Irreversible Capacity ◽  
Capacity Loss ◽  
Cation Migration ◽  
Li Ion ◽  
Layered Cathodes

Interlayer cation migration in layered cathodes, which can lead to irreversible capacity loss, is affected by surrounding transition metals.

Sign in / Sign up

Export Citation Format

Share Document