Chemistry Letters, Ahead of Print.
Monthly Archives: September 2023
Copper-mediated Trifluoromethylthiolation of Alkenyl Iodides with AgSCF3
Chemistry Letters, Ahead of Print.
Alkaline Ni‐Zn Rechargeable Batteries for Sustainable Energy Storage: Battery Components, Deterioration Mechanisms, and Impact of Additives
The demand for long-term, sustainable, and low-cost battery energy storage systems with high power delivery capabilities for stationary grid-scale energy storage, as well as the necessity for safe lithium-ion battery alternatives, has renewed interest in aqueous zinc-based rechargeable batteries. The Alkaline Ni-Zn rechargeable battery chemistry was identified as a promising technology for sustainable energy storage applications, albeit a considerable investment in academic research, it still fails to deliver the requisite performance. It is hampered by a relatively short-term electrode degradation, resulting in a decreased cycle life. Dendrite formation, parasitic hydrogen evolution, corrosion, passivation, and dynamic morphological growth are all challenging and interrelated possible degradation processes. This Review elaborates on the components of Ni-Zn batteries and their deterioration mechanisms, focusing on the influence of electrolyte additives as a cost-effective, simple, yet versatile approach for regulating these phenomena and extending the battery cycle life. Even though a great deal of effort has been dedicated to this subject, the challenges remain. This highlights that a breakthrough is to be expected, but it will necessitate not only an experimental approach, but also a theoretical and computational one, including artificial intelligence (AI) and machine learning (ML).
Molecular Docking‐Based Identification of Potential Natural Neuroprotective Molecules for Parkinson’s Disease
Abstract
Background: Parkinson's disease (PD) is a common progressive neurodegenerative and the prevailing treatments are ineffective in the early stages of the disease. Therefore, other strategies must be devised to halt the steady decrease of dopaminergic neurons in the brain. In Parkinson's disease, a dysregulated ACE/Ang II/AT1R axis in the brain causes free radical damage, apoptosis, and neuronal destruction. Current PD treatments only alleviate symptoms and do not reverse the degradation mechanism of dopaminergic neurons. As a result, it is critical to discover alternate, dependable medicines for the treatment of Parkinson's disease. Method: In the present study, homology modelling of MAS receptor, in silico docking and molecular dynamic studies (MDS) were employed to determine the efficacy of flavonoids as MASR activators. Result: The flavonoids Pterosupin and Amentoflavone exhibited best binding and therefore, the stability of these complexes were evaluated with MDS studies. The Pterosupin-MASR complex demonstrated better stability, stronger interactions and minimal fluctuation than the Amentoflavone-MASR complex. Conclusion: The data from the present study indicated that the flavonoid Pterosupin possesses better binding, favourable pharmacokinetic properties and stability. However, subsequent in vitro and in vivo assessments are necessary to validate its efficacy.
Manganese‐catalyzed Dehydrogenation of Amido Alcohols through Liberation of Hydrogen for the Synthesis of Oxazoles
Syntheses of important classes of (heterocyclic) compounds, the sustainable generation of hydrogen, and the use of abundantly available metals are highly desirable. We introduce here a catalytic oxazole synthesis. Our reaction is a regio selective, one-pot reaction and starts from esters and amino alcohols. Both are abundantly and diversely available and inexpensive starting materials. Hydrogen is liberated during the reaction and a molecular earth-abundant metal catalyst, a Mn(I) compound, mediates the reaction most effectively - and more efficiently than Ir and Ru catalysts. None of the oxazole derivatives synthesized, except the screening substrate and an active ingredient of a drug (an application), have been reported in literature yet.
Fabrication of mesoporous CrTe supported on graphitic carbon nitride as an efficient electrocatalyst for water oxidation
The synthesized composite material shows lower overpotential of 187 mV as well as lower Tafel slope value than the individual materials. It also shows excellent stability, which makes it suitable as electrocatalyst for water splitting.
It is essential to produce oxygen evolution reaction (OER) electrocatalysts, which are active and enduring for water electrolyzers. In order to create the effective OER, new chromium telluride/graphitic carbon nitride (gCN/CrTe) is produced via simple hydrothermal method. In this case, catalyst super hydrophilic surface is developed by the addition of 10% gCN nanosheets that can optimize the revelation of active sites and encourage the mass dispersion. Due to the robust contact among CrTe and gCN, which causes a lattice strain and an increase in the electron density around Cr sites, regulating the bonding between the catalyst and chemical intermediates. The improved 10% gCN/CrTe nanocomposite offers not only a good endurance but also by the highest mass activity. The synthesized 10% gCN/CrTe electrocatalysts provided low overpotential around 187 mV for OER to achieve a current density of 10 mA/cm2 in alkaline media with 51.0 h of long durability. Paving the way for innovative applications, this will enable the manipulation of advanced materials' fundamental properties at the atomic scale.
Polymerization of isoprene, myrcene, and butadiene catalyzed by cobalt complexes supported with 2‐acetyl‐6‐iminopyridine ligand
2-Acetyl-6-iminopyridine ligand-supported cobalt catalyst is highly active in isoprene, myrcene, and butadiene catalytic polymerization. The catalytic performances are stable against temperature, cocatalyst feeding, and monomer ratio.
Cobalt complexes carrying 2-acetyl-6-iminopyridine ligand are synthesized and characterized. Single-crystal X-ray diffraction reveals the cobalt ion is chelated with two nitrogen atoms and an acetyl oxygen atom additionally. A significant prolonged Co–O distance (2.3960(57) Å) is found, indicative of a labile character. Activated by diethylchloroaluminum, all complexes show high conversion rates for isoprene and myrcene polymerizations, affording cis-1,4/3,4 regulated 1,3-diene polymers. The polymerization of butadiene, interestingly, gives predominant cis-1,4 selectivity (>99.2%) with moderate activity. The substituent at ortho-position of arylimine plays a minor role in controlling activity and selectivity as well as the molecular weight of the resultant polymers. The properties of resultant poly(1,3-diene)s are stable even in a wide range of operational conditions, such as [Al]/[Co] varied from 20 to 600, temperature spanning from 0°C to 60°C, and monomer–catalyst ratio from 1000 to 4000. These additional benefits of minimum fluctuation in catalytic performances may be suitable for industrial polymerization process.
Copper Nitrate‐Mediated Selective Bond Cleavage of Alkynes: Diverse Synthesis of Isoxazoles
An unprecedented copper nitrate-mediated bond cleavage of alkynes was developed for the modular synthesis of isoxazoles, where either C—S bond or C≡C triple bond was cleaved selectively.
Comprehensive Summary
An unprecedented copper nitrate-mediated bond cleavage of alkynes was developed for the modular synthesis of isoxazoles, where either C—S bond or C≡C triple bond was cleaved selectively. Substituents attached to the C≡C triple bonds could differentiate the chemical bonds cleavage and reaction pathways disparately. Various transformations of products illustrate promising applications of the given protocols.
The effect of structural variations of heteroleptic Cu(II) complexes of tri‐dentate unsymmetrical Schiff‐base main ligands with pyridine or bithiazole co‐ligands on molecular docking against SARS‐CoV‐2 and its Omicron variant main proteases
Meso-1,2-diphenyl-1,2-ethylenediamine was reacted with salicylaldehyde derivatives, copper(II) perchlorate, and pyridine to produce various four-coordinated heteroleptic [Cu (SBn)(py)]ClO4 (n = 1–4) complexes. Ligand exchange of the monodentate pyridine with bidentate 2,2′-dimethyl-4,4′-bithiazole (BTZ) produced other new series of five-coordinated [Cu (SBna)(BTZ)]ClO4 complexes. Elemental analysis, Fourier-transform infrared spectroscopy (FT-IR), and ultraviolet–visible (UV–Vis) spectroscopy were used to identify the complexes. The crystal structures of 1a and 2a were also determined by single-crystal X-ray crystallography (SCXRC). The inhibitory potential of these complexes against SARS-CoV-2 and its omicron variant main proteases (PDB IDs: 6LU7 and 7TLL, respectively) was investigated by means of molecular-docking modeling. According to the estimated free binding energy (EFBE), the order of binding energies were (3) > (3a) > (1a) > (1) > (2a) > (4a) > (4) > (2) for 6LU7 and (1a) > (3) > (1) > (4) > (2) > (4a) > (2a) > (3a) for 7TLL. The complexes (1a) for 6LU7 and (3) for 7TLL with electronegative Br substituents were at the top of the series and had the most negative ΔGbinding. The EFBE of four conventional corona-virus medicines, that is, remdesivir, hydroxychloroquine, dexamethasone, and AstraZeneca were also obtained and compared with the synthesized complexes. The EFBE of the complexes were comparable to standard drugs.
Tailoring chemical absorption–precipitation to lower the regeneration energy of a CO2 capture solvent
Solvent-based CO2 capture consumes significant energy in solvent recovery. To improve energy efficiency, this study investigates CO2 fixation in a solid form through solvation followed by ionic self-assembly–aided precipitation without requiring high energy for solvent regeneration. Based on hypothesis that CO2−3 ions may bind with monovalent metal ions such as Na+, we introduce monovalent Na+ into an aqueous hexane-1,6-diamine solution where CO2 forms carbamate and bicarbonate. Then, Na+ in the solvent act as a seed for ionic self-assembly with diamine carbamate to form an intermediate ionic complex. The recurring chemical reactions lead to an ionic solid formation, which can be easily removed through sedimentation or centrifugation from the aqueous solvent and heated to release the captured CO2. Direct heating of the solids leads to separation of CO2 via decomposition of a solid CO2-diamine-Na molecular aggregate, requiring as low as ~3.4 GJ/t CO2, which is significantly lower than the state-of-the-art polyethyleneimine, CaCO3, and bis-iminoguanidines systems, which require 3.5−10.2 GJ/t CO2. Molecular dynamic simulations support our hypothesis with the use of Na+ to form relatively less stable, yet sufficiently solid, complexes for the least energy-intensive recovery of diamine solvents compared with bivalent carbonate–forming ions.