The systematic method for constructing Lewis representations is a method for representing chemical bonds between atoms in a molecule. It uses symbols to represent the valence electrons of the atoms involved in the bond. Using a number of rules in a defined order, it is often better suited to complicated cases than the Lewis representation of atoms. This method allows us to determine the formal charge and oxidation number of each atom in the edifice more efficiently than other methods.
Two organic-inorganic hybrid materials, C6H4(NH3)2∙Cl2 (I) and β-[C6H10N2]2ZnCl4 (II), have been synthesized by hydrothermal method. These two materials are one of the hybrid materials have emerged as one of the most brilliant components classes. These extraordinary compounds synergistically combine the desired physical properties of both organic and inorganic components into a single compound offering the possibility to achieve great improvement over time in terms of science across various sectors. Their structures were determined by XRD pattern investigations and single crystal X-ray diffraction. These two compounds are crystallized in the monoclinic system; C2/c space group. In the both structures, the anionic-cationic entities are interconnected by hydrogen bonding contacts and p-p Interaction forming three-dimensional networks. Intermolecular interactions were investigated by Hirshfeld surfaces and the contacts of the four different chloride atoms in (II) were compared. The vibrational absorption bands were identified by infrared spectroscopy. These compounds were also investigated by solid state13C NMR spectroscopy.
The Zn and Fe modified S2O8-2/ZrO2-Al2O3 catalyst (Zn-Fe-SZA) was prepared and mechanisms of deactivation and methods for regeneration of as-prepared catalyst were explored with n-pentane isomerization as a probe reaction. The results indicated that the isopentane yield of the fresh Zn-Fe-SZA-F catalyst was about 57% at the beginning of the run, and declined gradually to 50% within 1500 min, then fell rapidly from 50% to 40% between 1500 and 2500 minutes. The deactivation of Zn-Fe-SZA catalyst may be caused by carbon formation on surface of the catalyst, sulfate group attenuation owing to reduction by hydrogen, removal of sulfur species and the loss of strong acid sites. It was found that the initial catalytic activity over Zn-Fe-SZA-T catalyst was 48%, which recovered by 84.3% as compared to that of fresh catalyst (57%). However, it showed a sharp decrease in isopentane yield from 48% to 29% within 1500 minutes, showing poor stability. This is associated to the loss of acidity caused by removal of sulfur species cannot be basically restored by thermal treatment. Resulfating the calcined catalyst could improve the acidity of catalyst significantly, especially strong acid sites, as compared with the calcined sample. The improved stability of the resulfated catalyst can be explained by: 1) eliminaton of carbon deposition to some extent by calcination process, 2) formation of improved acidic nature by re-sulfation, favoring isomerization on acidic sites, 3) restructuring of the acid and metal sites via the calcination-re-sulfation procedure.
Activated carbons calcined at 400˚C and 600˚C (AC-400 and AC-600), prepared using palm nuts, collected in the town of Franceville in Gabon, were used to study the dynamic adsorption of MnO4- ions in acidic media on fixed bed column and on the kinetic modeling of experimental data of breakthrough curves of MnO4- ions obtained. Results on the adsorption of MnO4- ions in fixed-bed dynamics obtained on AC-400 and AC-600 adsorbents beds indicated that the AC-400 bed appears to be the most efficient in removing MnO4- ions in acidic media. Indeed, the adsorbed amounts, the adsorbed capacities at saturation and the elimination percentage of MnO4- ions obtained with AC-400 (31.24 mg; 52.06 mg·g-1 and 41.65% respectively) were higher compared to those obtained with AC-600 (9.87 mg; 16.45 mg·g-1 and 17.79% respectively). The breakthrough curves kinetic modeling revealed that the Thomas model and the pseudo-first-order kinetic model were the most suitable models to describe the adsorption of MnO4- ions on adsorbents studied in our experimental conditions. The results of the intraparticle diffusion model showed that intraparticle diffusion was involved in the adsorption mechanism of MnO4- ions on investigated adsorbents and was not the limiting step and the only process controlling MnO4- ions adsorption. In contrast to AC-400, the intraparticle diffusion on AC-600 bed plays an important role in the adsorption mechanism of MnO4- ions.
Using two new flexible and functional nitronyl nitroxide radicals as ligands, two copper (II) complexes {[Cu(hfac)2]3(NITmPhO3Py)2}n (1) and [Cu(hfac)2 (NIToPhO3Py)]2 (2) (NITmPhO3Py = 2-[(3-methoxy-pyridinyl)phen-3-yl]- 4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, NIToPhO3Py = 2-[(3-methoxy-pyridinyl)phen-2-ly]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, hfac = hexafluoroacetylacetone), have been characterized structurally and magnetically. The X-ray crystal analyses showed that complex 1 displayed a chain polymer structure which formed with {[Cu(hfac)2]3(NITmPhO3Py)2}n due to the cross-linking of two cyclic binuclear fragments {[Cu(hfac)2]2(NITmPhO3- Py)2} via the bridging unit [Cu(hfac)2]; complex 2 presented a binuclear cyclic structure [Cu(hfac)2]2(NIToPhO3Py)2. The magnetic behaviors of the two complexes 1 and 2 have been investigated. Magnetic studies showed that antiferromagnetic interactions dominated in complex 1, while there existed ferromagnetic interactions between Cu(II) and coordinated NO group in complex 2.
Li-ion batteries (Libs) are a mature technology widely used for energy storage in various electronic devices. Nowadays, this technology has become a leading candidate for the portable electronics market and for electric vehicles due to its good performance. As a result, the demand for Libs containing critical metals, rare earth elements and precious metals is increasing day by day with the accelerated upgrades of consumer electronics, which promotes the supply risk of many mining resources. In addition, the problems associated with the production of end-of-life Lib are increasing on a global scale. Used Libs are e-waste containing significant levels of critical raw materials (such as Co, Li, Mn and Ni) along with harmful substances. Without proper management of Lib waste, these precious metals and toxic substances may end up in nature and cause environmental and public health problems. In order to preserve nature, ensure sustainable resource management and stimulate the circular economy, it has become crucial to properly manage and recycle end-of-life Li-ion batteries. By the way, conventional methods focusing on pyrometallurgical treatments combined with hydrometallurgical treatment are widely studied to recover design metals from Libs waste. It is in this context that we have conducted this bibliographic synthesis, focusing on the efficiency of the solvents employed and their competitiveness for a more environmentally friendly economic management. In this manuscript, recent leaching, solvent extraction, electrodeposition and precipitation strategies to recover precious metals from end-of-life Li-ion battery designs are reviewed and the evolution of these processes is discussed.
Seven transition metal complexes of Mn 2+ , Ni 2+ , Co 2+ , Cu 2+ and Zn 2+ with 3-aminopyridine (3-APy) as ligand have been synthesized, characterized by different techniques and their antibacterial activities were studied. Molecular modeling calculations were performed using DMOL 3 program in materials studio package which is designed for the realization of large scale density functional theory calculation (DFT). The quantum mechanical and chemical reactivity parameters such as chemical hardness, chemical potential, electronegativity, electrophilicity index and Homo-Lumo energy gap were obtained theoretically and were used to understand the biological activity of the prepared compounds. Some complexes were tested for their in-vitro cytotoxic activity in human lung cancer cell lines (A-549 cell line), and structure-activity relationships were established. In general, the coordination to Co 2+ increased the cytotoxicity while the Ni 2+ complexes show reduced cytotoxic activity compared to the metal-free 3-aminopyridine.
New solid complexes derived from the reaction of aroyl hydrazones, 2hydroxy-1-naphthaldehyde benzene sulphonyl hydrazone (HNB), and 2hydroxy-1-naphthaldehyde p-toluene sulphonyl hydrazone (HNT), with Co 2+ , Ni 2+ , and Cu 2+ salts have been isolated and characterized using elemental analyses, spectral (UV-vis., IR), molar conductivity and magnetic measurements.The modes of bonding as well as the stereochemistry of the isolated solid complexes were discussed.The results suggested that both HNB and HNT coordinated with the metal ions in a bidentate manner forming a polymeric chain in the case of HNB while monocular complexes were formed in the case of HNT.The amounts of solvent in the solid complexes were determined by TGA measurements.Also, spectral studies of HNT with Co 2+ and Fe 3+ ions in solution were carried and the ratio of complexes was determined by continuous variation, molar ratio, and slope ratio methods.Moreover, the results suggest the formation of 1:1 (M:L) for Co 2+ ions while three species with ratios of 1:1, 1:2, and 2:1 (M:L) have been observed in the case of Ni 2+ and Cu 2+ .Finally, conductance titration of HNB and HNT with Co 2+ ion elucidates the formation of two species with ratios 1:1 and 1:2 (M:L) in the case of the Co 2+ -HNB while 1:1 (M:L) belongs to the Co 2+ -HNT system.
The Schiff base, 1-phenyl-1-(pyridin-2-yl)-N-(pyrimidin-2-yl)methanimine dihydrate (L 1 ) has been synthesized by the condensation reaction between 2-aminopyrimidine and 2-benzoylpyridine and characterized using 13 C-NMR, 1 H-NMR, microanalysis, FT-IR, DEPT-135, HSQC, HMBC, COZY, NOESY.The reaction of 1-phenyl-1-(pyridin-2-yl)-N-(pyrimidin-2-yl)methanimine dihydrate (L 1 ) with salts of V(IV), Co(II) and Cu(II), however, resulted in the hydrolysis of L 1 to give binuclear metal complexes of 2-benzoylpyridine (L 2 ) and phenyl(pyridin-2-yl)methanediol (L 3 ) which were characterized using UV-visible spectroscopy, and TGA.The single crystal x-ray structure determined for the Copper(II) complex revealed that we obtained a compound previously obtained using a different method of synthesis.The Schiff base ligand (L 1 ) is soluble in methanol, ethanol, DMSO, acetone and DMF.Microanalysis and Spectroscopic studies indicated that binuclear metal complexes were obtained by the coordination of metal ion to 2-benzoylpyridine (L 2 ) and phenyl(pyridin-2-yl)methanediol (L 3 ) from the hydrolysis of L 1 .Spectroscopic and elemental analysis reveal the formation of square pyramidal complexes of Co(II) and Cu(II) and a square planar complex of V(IV).In vitro antibacterial and antifungal activity against three bacterial strains (Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus) and three fungal stains (Candida albicans, Candida glabrata and Candida parapsilosis) showed moderate biological activity.Antioxidant studies reveal that only the binuclear How to cite this paper:
Two novel copper complexes (1,2) with N,O-donor ligands were synthesized by reaction of copper(II) malonates with 3,3’-bis(pyrazolyl)pentane and 4,4’-trimethylenedipyridine in methanol at moderate temperature. These compounds were characterized by elemental analysis, UV-VIS, IR spectroscopies and powder X-ray diffraction analyses. Compound (1) melts at higher temperature (202°C) than compound (2) (100°C). The IR spectra showed typical vibrations related to C=N and C=C, characteristic of pyrazolyl and pyridine ligands.
Reaction of zinc acetate, potassium thiocyanate and the ligand 3-ampy gave the discrete tetrahedral complex [Zn(NCS)2(3-ampy)2] in which 3-ampy chelates in a monodentate fashion through its pyridine-N atom. It was characterized by single crystal X-ray diffraction, infrared, and elemental analysis. Density Functional Theory calculations were performed in order to gain insights into the role of weak molecular interactions in the complex that influence the self-assembly process and crystal packing. X---H (X = H, C, N and S) inter-actions. S-H interactions (30.2%) were found to be the main interactions that hold the molecules in the crystal structure. Furthermore, the thermolysis of the complex was studied in order to evaluate whether it was suitable as a precursor for zinc sulphide.
Two new M(II)-radical complexes [M(hfac)2(IM-o-QN)] (M = Ni(1), Zn(2); IM-o-QN = 4'-quinoxalinyl-substituted imino nitroxide; hfac = hexafluoroa-cetylacetonate) have been synthesized and characterized by X-ray diffraction analysis, element analyses, IR and UV-Visible spectroscopy. X-ray analysis reveal that the structures of both complexes are similar configuration and differently spatial symmetries. The complex 1 crystallizes in the triclinic Pī space group with the respective cell parameters: a = 9.1189(18) Å, b = 9.836(2) Å, c = 18.537(4) Å, α = 75.92(3)°, β= 81.95(3)°, γ = 69.32(3)°, V = 1506.1(5) , Z = 2, whereas the complex 2 is in monoclinic C2/c space group with the respective cell parameters: a = 26.996(5) Å, b = 9.5223(19) Å, c = 23.961(5) Å, α = 90.00°, β= 91.07(3)°, γ= 90.00°, V = 6158(2) , Z = 8. In two new M(II)-radical complexes, the central M(II)(Ni(1) and Zn(2)) ions are coordinated by four oxygen atoms from two hfac and two nitrogen atoms from imino nitroxide radicals to form a distorted octahedron. Additionally, the optical properties and thermal analysis of the two complexes are reported.
