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Electrocatalytic properties of La1-xCuxCoO3 (0 ≤ x ≤ 0.8) film electrodes for oxygen evolution in alkaline medium: Part II. A comparative study

2019-12-18T05:55:51Z

Title: Electrocatalytic properties of La1-xCuxCoO3 (0 ≤ x ≤ 0.8) film electrodes for oxygen evolution in alkaline medium: Part II. A comparative study Authors: Yadav, Manish Kumar; Lal, Basant; Singh, Narendra Kumar Abstract: The present study is concerned with the preparation of perovskite-type oxide film electrodes of La, Cu and Co having composition La_1-xCu_xCoO₃ (0 ≤ X ≤ 0.8) on Ni conducting support and study of their electrocatalytic properties towards oxygen evolution reaction (OER) in alkaline medium. Materials have been synthesized by using malic acid sol-gel route at pH 4.00. X-ray diffraction study of the material indicated the formation of almost pure perovskite phase with hexagonal crystal geometry. The electrocatalytic activity of the material has been determined in three electrode single compartment glass cell. Techniques used in the electrochemical studies are cyclic voltammetry (CV), oxide roughness factor and anodic polarization (Tafel plot). Each cyclic voltammogram exhibits an anodic and a corresponding cathodic peak prior to the oxygen evolution reaction. The observed anodic and cathodic peak potential values are 553±31 and 312±27 mV, respectively. The study of anodic polarization curve indicates that the oxide with 0.6 mol Cu-substitution (j_a = 182.4 mA cm^-2 at 750 mV) shows highest electrocatalytic activity with lowest Tafel slope value (b = 65 mV decade^-1) towards OER. Thermodynamic properties of the material have also been investigated by recording the anodic polarization curve at different temperatures. The value of electrochemical activation energy has been found to be lowest with most active 0.6 mol Cu-substituted oxide material. Electrocatalytic activities of the oxide electrodes, so obtained, have been compared with the similar oxide prepared at 3.75 pH. Page(s): 1295-1301

Crystal structure, thermal analyses, and acetate binding properties in Zinc(II) complex of a urea-functionalized pyridyl ligand

2019-12-18T05:52:29Z

Title: Crystal structure, thermal analyses, and acetate binding properties in Zinc(II) complex of a urea-functionalized pyridyl ligand Authors: Yang, Zaiwen; Sun, Shasha; Liu, Yilong; Liu, Xiangrong; Zhao, Shunsheng; Zhang, Zhen; Chen, Xinjuan; Yang, Zheng; Jia, Xiaodan Abstract: A zinc(II) acetate complex with a urea-functionalized pyridyl ligand, [ZnL₂(OAc)₂]·2H₂O (1) (L = N-(4-chlorophenyl)-N'-(4-pyridyl)urea), has been synthesized by the reaction of L with Zn(OAc)₂·2H₂O under water-containing condition. X-ray single-crystal diffraction analyses reveal that 2-D sheetlike network structure has been formed by the urea N−H×××N_pyridyl interactions and C–H···O interactions in the free ligand L. Complex 1 features 3-D hydrogen bonded network formed by intermolecular N−H···O hydrogen bonds and O−H×××O hydrogen bonds involving urea groups, acetate anions and bridged water molecules. The hydrogen bonds play an important role in stabilizing the supramolecular structures. Thermal gravity analyses have been used to investigate the thermal stabilities of L and 1, and the apparent activation energy (E_a) of the decompositions have also been calculated, and the results indicate that the main decomposition of L needs higher apparent activation energy values E_a than that of 1. The acetate binding properties of L in solution have also been evaluated by Ultraviolet-Visible (UV-Vis) spectroscopy. CCDC: 1506202, L; 1506203, 1. Page(s): 1302-1310

Theoretical study of structural effects on reactivity and stability of isomeric pyrano-, thiopyrano- and selenopyranopyrroles

2019-12-18T05:49:10Z

Title: Theoretical study of structural effects on reactivity and stability of isomeric pyrano-, thiopyrano- and selenopyranopyrroles Authors: Khodaei, Mohammad Mehdi; Alizadeh, Abdolhamid; Ghanbari, Parvin Abstract: In this study we have calculated global and local DFT reactivity descriptors for isomeric pyrano-, thiopyrano- and selenopyranopyrroles. The geometric optimization of the obtained structures have been realized with the density functional theory (DFT, B3LYP) at the level of 6-311G(d,p) and show these isomers have planar configurations. The structural properties such as dipole moments, bond lengths and bond angles of these isomers have been calculated. The heats of formation have also been calculated based on the optimized geometry. The energies of HOMO and LUMO molecular orbitals have been used to determine several global descriptors as a measure of their electronic properties, relative stabilities and chemical reactivities. These include total energy (E), ionization potential (I), electron affinity (A), chemical hardness (η), chemical softness (S), electronic chemical potentials (μ) and electrophilicity (ω). Selenopyrano[2,3-c]pyrrole possesses the highest electrophilicity and minimum chemical hardness among the calculated isomeric structures. The largest calculated dipole moment belongs to pyrano[2,3-c]pyrrole, while thiopyrano[3,4-b]pyrrole has the lowest. Page(s): 1311-1318

Preparation, structural characterization, antimicrobial and anticancer activities, DFT and molecular docking studies of a nano ferrocenyl Schiff base and its metal complexes

2019-12-18T05:45:27Z

Title: Preparation, structural characterization, antimicrobial and anticancer activities, DFT and molecular docking studies of a nano ferrocenyl Schiff base and its metal complexes Authors: Mahmoud, Walaa H; Deghadi, Reem G; Mohamed, Gehad G Abstract: An organometallic Schiff base (2-(1-((4-aminopyridin-3-yl)imino)ethyl)cyclopenta-2,4-dien-1-yl) (cyclopenta-2,4-dien-1-yl)iron (L) and eight transition metal complexes have been prepared by reacting 3,4-diaminopyridine with 2-acetylferrocene in 1:1 molar ratio for ligand formation and by reacting Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) chlorides with ligand in 1:1 molar ratio for complexes formation. All prepared compounds have been characterized by using elemental analysis (C, H, N, M), molar conductance, IR, UV-Vis, ¹H-NMR, SEM and mass spectral analysis. Also, their TG and DTG behaviors have been studied. All complexes have an octahedral structure. The ligand coordinated to the metal ions through the nitrogen atoms of azomethine and amino groups. In addition, computational studies of the synthesized Schiff base ligand have been carried out by the DFT/B3LYP method. The antimicrobial activities of the ligand and its metal complexes have been studied by using different bacterial species [Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Salmonella typhimurium] and fungal species included [Aspergillus fumigatus and Candida albicans]. Moreover, the prepared compounds have been evaluated for anticancer activities against breast cancer (MCF-7) and normal melanocytes (HFB-4) cell lines. Docking studies have been used to determine the probable binding mode between the ligand and its Cd(II) complex with the active site of 3HB5, 2HQ6 and 1GS4 receptors. Page(s): 1319-1337