Five Schiff bases containing a thiadiazole moiety have been used as poly(vinyl chloride) photostabilizers at low concentrations. The efficiency of Schiff bases as photostabilizers was investigated using various techniques, for example, the changes in poly(vinyl chloride) infrared spectra, molecular weight, chain scission quantum yield, and surface morphology were monitored upon irradiation with an ultraviolet light. Evidently, all the additives used inhibited poly(vinyl chloride) photodegradation at a significant level. The most efficient Schiff base exhibited a high level of aromaticity and contained a hydroxyl group. It seems possible that such photostabilization could be due to the direct absorption of ultraviolet radiation by the additives. In addition, Schiff bases could act as radical scavengers and proton transfer facilitators to stabilize the polymeric materials.

This study describes preparation a new series of tetra-dentate N2O2 dinuclear complexes Cr(III), Co(II)and Cu(II) of the Schiff base 2-[5-(2-hydroxy-phenyl)-1,3,4-thiadiazol-2-ylimino]-methyl-naphthalen-1-ol], (LH2) derived from 1-hydroxy-naphthalene-2-carbaldehyde with 2-amino-5-(2-hydroxy-phenyl)-1,3,4-thiadiazole. These ligands were characterized by FT-IR, UV-Vis, Mass spectra, elemental analysis, and 1H-NMR. All prepared complexes have been characterized by conductance measurement, magnetic susceptibility, electronic spectra, infrared spectrum, thermal Analysis (TGA), and metal analysis by atomic absorption. The stoichiometry of metal to ligand, magnetic susceptibility, and electronic spectra measurements show an octahedral geometry for all (Cr3+, Co2+, Cu2+) complexes. Conductivity measurement shows that the prepared (Co2+, Cu2+) complexes were nonelectrolyte except (Cr3+). Studying the extraction efficiency such as ligand concentration, temperature and incubation time, centrifuge time, amount of surfactant were evaluated and optimized. The linear range of ions Cr(III), Co(II) and Cu(II) with ligand (0.2–3, 0.2–4, 0.2–3, µg mL–1), each individually, and relative standard deviation (0.15%, 0.34%, 0.46%). The successful method was applied for the determination of trace metal ions in the wastewater.

This study involves the preparation of a new series of dinuclear complexes Cr(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes of the Schiff base (H2L) derived from Vanillin with 2amino-5-(2-hydroxy-phenyl)-1,3,4-thiadiazole has been synthesized tetradentate Schiff base ligands were used for complexation upon two metal ions of Cr(III),Co(II), Ni(II), Cu(II) and Zn(II) as dineucler formula M2L2.4H2O and M2L2. These ligands can be characterization IR ,UV-Vis , Mass, 1 H-NMR and elemental microanalysis. The Synthesized complexes were characterized by IR, spectroscopy ,elemental microanalysis, electronic spectra, magnetic susceptibility conductive ,thermal Analysis (TGA) and atomic absorption on the basis of analytical data, the stoichiometry of metal to ligand in complexes and Schiff bases ligand. The Structures of complexes were proposed from the measurements. The bioactivity of the prepared complexes has been examined with antibacterial activity. Antimicrobial activities of the Schiff base ligand and their metal complexes reveal that the Schiff base transition metal complexes show significant activity against some fungi and bacteria.

An environmentally friendly method for the synthesis of Schiff bases was described by combining 4,4-methylenediantipyrine with ethylenediamine. The complex was prepared in a classical way, the usual condensation reaction method. A series of metal complexes were prepared from reactions of lanthanide nitrate salts [Nd+3, La+3, Er+3, Gd+3, and Dy+3] with a Schiff base ligand. The structures of the complexes were confirmed by analytical studies, spectral measurements, and thermal studies, and the prepared ligand was characterized using microanalysis technique, UV-Visible, infrared, nuclear magnetic resonance 1H-NMR and 13C-NMR, mass spectrometry, and thermogravimetric analysis (TGA), and the addition of conductivity measurement and magnetic moment of complexes. The results showed that these complexes have a consistency of 10 in which the elements are bonded with the ligand through the two nitrogen atoms at C=N and that the bonding ratio between the metal:ligand is in 1:2 ratio. By using agar disc-spreading, we tested several in vitro compounds for their antibacterial activity against four pathogenic bacteria, including Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Klebsiella pneumoniae. The majority of the complexes demonstrated antibacterial activity.

New metal complexes of the ligand 2-[5-(Pyridin-2-ylmethylene)-amino] 1,3,4-thiadiazol-2-ylphenol (L) with the metal ions Co(II), Ni(II), Cu(II) and Zn(II) were prepared in alcoholic medium. The Schiff base was condensed [2-pyridine carbxaldehyde] with [2-amino-5-(phenyl-1,3,4oxadiazole] in alcoholic medium. Two tetradentate Schiff bases ligand were used for complexation upon two metal ions of Co 2+, Ni 2+, Cu 2+ and Zn 2+ as dineucler formula M2L2. The synthesized compound and their metal complexes were characterized by FTIR Spectroscopy, electronic spectroscopy, Elemental analysis, magnetic susceptidbility measurements, thermal analysis , 1 H-NMR spectra, and mass spectra. The activation thermodynamic parameters such as ΔE * , ΔH * , ΔS * and ΔG * were calculated from the TGA curve using Coats-Red fern method. From the measurements, structures of the complexes were proposed.

The study involved preparing a new compound by combining Schiff bases generated from compounds for antipyrine, including lanthanide ions (lanthanum, neodymium, erbium, gadolinium, and dysprosium). The preparation of the ligand from condensation reactions (4-antipyrinecarboxaldehyde with ethylene di-amine) at room temperature, and was characterization using spectroscopic and analytical studies ( FT-IR, UV-visible spectra, 1 H-NMR, mass spectrometry, (C.H.N.O), thermogravimetric analysis (TGA), in addition to the magnetic susceptibility and conductivity measurement of the synthesis complexes, among the results we obtained from the tests, we showed that the ligand behaves with the (triple Valence) lanthanide ions, the multidentate behavior through two oxygen atoms of the carbonyl group and two nitrogen atoms of the azomethine group with all the prepared complexes in a molar ratio (1:1). The participation of six groups of bidentate nitrate in the coordination and indicating that their complexes have values of magnetic moment and paramagnetic character and, based on the results of those measurements, the geometrical shape of the complexes was proposed. The biological activity of the prepared complexes was studied using the antibacterial activity, as the results of its effectiveness showed the direction of the bacteria used (Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Klebsiella pneumoniae) at the concentration of 1×10 -3 M

Hydrofluoric acid has been one of the important chemicals in the industry. In Iraq, there is a considerable consumption of it in petrochemicals and detergents industry. However, so far, there is no genuine evaluation for the hazards and any prospective procedures to minimise the risk of it. In this regard, we show here some accidents took place in some industrial amenities in Iraq and other Arabic countries. In addition, there is an elaborated description of the degree of risk, safety practices, and some feasible treatments for hydrofluoric acid burns and inhalations.

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