Abdulaziz M. Ajlouni

Syntheses, characterization, biological activity and fluorescence properties of bis-(salicylaldehyde)-1,3-propylenediimine Schiff base ligand and its lanthanide complexes.

Eight new lanthanide metal complexes [LnL(NO(3))(2)]NO(3) {Ln(III) = Nd, Dy, Sm, Pr, Gd, Tb, La and Er, L = bis-(salicyladehyde)-1,3-propylenediimine Schiff base ligand} were prepared. These complexes were characterized by elemental analysis, thermogravimetric analysis (TGA), molar conductivity measurements and spectral studies ((1)H NMR, FT-IR, UV-vis, and luminescence). The Schiff base ligand coordinates to Ln(III) ion in a tetra-dentate manner through the phenolic oxygen and azomethine nitrogen atoms. The coordination number of eight is achieved by involving two bi-dentate nitrate groups in the coordination sphere. Sm, Tb and Dy complexes exhibit the characteristic luminescence emissions of the central metal ions attributed to efficient energy transfer from the ligand to the metal center. Most of the complexes exhibit antibacterial activity against a number of pathogenic bacteria.

Thermal decomposition of lanthanide(III) complexes of bis-(salicylaldehyde)-1,3-propylenediimine Schiff base ligand

The thermal decomposition of lanthanide complexes, with a general formula: [LnL(NO3)2](NO3), where Ln = La, Pr, Nd, Sm, Gd, Tb, Dy, and Er; and L = bis-(salicyladehyde)-1,3-propylenediimine Schiff base ligand, was studied by thermogravimetric (TG) and derivative thermogravimetric (DTG) techniques. The TG and DTG data indicated that all complexes are thermostable up to 398 K. The thermal decomposition of all Ln(III) complexes was a two-stage process and the final residues were Ln2O3 (Ln = La, Nd, Sm, Gd, Dy, Er), Tb4O7, and Pr6 O11. The activation energies of thermal decomposition of the complexes were calculated from analysis of the TG-DTG curves using the Kissinger, Friedman, and Flynn-Well-Ozawa methods.

Synthesis, characterization, biological activities and luminescent properties of lanthanide complexes with [2-thiophenecarboxylic acid, 2-(2-pyridinylmethylene)hydrazide] Schiff bases ligand

Abstract A Schiff base L [2-thiophenecarboxylic acid, 2-(2-pyridinylmethylene)hydrazide] with its lanthanide metal complexes was synthesized. These complexes were characterized by elemental analysis, molar conductivity measurements, spectral analysis (NMR, FT-IR, and UV-Vis), luminescence and thermal gravimetric analysis. The Schiff base ligand was a tridentate chelate and coordinates to the central lanthanide ion with 1:2 metal:ligand ratio. The conductivity data showed a 1:1 electrolytic nature with a general formula [LnL2(NO3)2]NO3. The luminescence emission properties for Sm, Tb, and Eu complexes were observed and showed that the ligand L could absorb and transfer energy to Sm(III), Tb(III) and Eu(III) ions. The complexes possessed a good antibacterial activity against different bacterial strains. In addition, the scavenging activity of the Ln(III) complexes on DPPH was concentration dependant and the complexes were significantly more efficient in quenching DPPH than the free Schiff base ligand.

Synthesis and Biological Activities of Lanthanide (III) Nitrate Complexes with N-(2-hydroxynaphthalen-1-yl) methylene) Nicotinohydrazide Schiff Base

BACKGROUND The field of coordination chemistry has registered a phenomenal growth during the last few decades. It is well known that precious metals have been used for medicinal purposes for at least 3500 years. At that time, precious metals were believed to benefit health because of their rarity, but research has now well established the link between medicinal properties of inorganic drugs and specific biological properties. METHODS The current study was designed to explain the synthesis and characterization of the lanthanide (III) nitrate complexes with N-(2-hydroxynaphthalen-1-yl) methylene) nicotinohydrazide schiff base and to evaluate the antibacterial and the antioxidant activities of the schiff base and its lanthanide ion complexes. Antimicrobial activity of the Lanthanide (III) nitrate complexes with N-(2- hydroxynaphthalen-1-yl) methylene) nicotinohydrazide schiff base was estimated by minimum inhibitory concentration (MIC, µg/mL) using a micro-broth dilution method for different clinical isolates such as Eschereshia coli and Enterococcus faecalis. The antioxidant activities of the ligand and its lanthanide complexes were tested using a UV-Visible spectrophotometer by preparing 5x10-4M of all tested samples and DPPH in Dimethyl sulphoxide (DMSO). RESULTS Our present study has shown that moderate antimicrobial activity exists against both ligand and its complexes. There was no significant difference between Gram-positive and Gram-negative bacteria towards the tested ligand and its complexes. The free ligand has scavenging activity between 13-21 % while all complexes are more efficient in quenching DPPH than free ligand. CONCLUSION The results obtained herein indicate that the ligand and its complexes have a considerable antibacterial activity as well as antioxidant activity in quenching DPPH.

A Thermodynamic Study of Complexation of Iron Ions with Clarithromycin and Roxithromycin in Methanol Using a Conductometric Method

The formation constants KML of Clarithromycin (CLA) and Roxithromycin (ROX) with Fe(III) and Fe(II) ions in methanol have been determined at various temperatures using a conductometric technique. The interaction yields complexes with metal-to-ligand compositions of 1:1. The conductivity data were analyzed using a computer program based on 1:1 stoichiometry from which the stability constants and the limiting molar conductance were obtained. The stability of these complexes was found to increase with temperature. Compared with Fe(II), Fe(III) forms more stable complexes with ROX and CLA. The values of the thermodynamic parameters enthalpies (ΔH∘), entropies (ΔS∘), and the derived Gibbs energies (ΔG∘) were deduced from the dependence of the formation constants on temperature. The positive values of ΔH∘ and ΔS∘ indicate that the complexation processes is enthalpically unfavorable but entropically favored. The negative values of ΔG∘ show the ability of the studied ligand to form stable complexes and that the complexation process is favorable.

DFT computational studies, biological and antioxidant activities, and kinetic of thermal decomposition of 1,10-phenanthroline lanthanide complexes

Abstract[Ln (phen)2(NO3)3] complexes were synthesized by interaction of lanthanide nitrate {Ln (NO3)3.xH2O where Ln = Tb, Eu, Sm, Dy, and La} with 1,10-phenanthroline {phen} in ethylacetate. The complexes were characterized by several analytical and spectroscopic techniques. Density functional theory (DFT) calculations were carried out to optimize the geometries of all prepared complexes at the B3LYP/6-31G(d) level of theory. Vibrational frequencies of the complexes theoretically calculated were in good agreement with experimentally determined values. Most of the complexes exhibited high to moderate antibacterial and antifungal activities in vitro against seven different clinical isolates. The complexes were tested for their antioxidant activity toward 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical. Dy(III) complex showed the highest activity. Thermal degradation of complexes at different heating rates was investigated by thermogravimetric analysis (TGA). The complexes had high thermal stability. The activation energies (Ea) of the degradation were calculated by Kissinger and Flynn-Wall-Ozawa methods.

Redetermination of [Gd(NO3)3(H2O)4]·2H2O

The crystal structure of the title compound, tetraaquatris(nitrato-κ2 O,O′)gadolinium(III) dihydrate, was redetermined from single-crystal X-ray data. In comparison with the first determination [Ma et al. (1991 ▶). Wuji Huaxue Xuebao, 7, 351–353], all H atoms could be located, accompanied with higher accuracy and precision. The GdIII atom shows a ten-coordination with three nitrate ligands behaving in a bidentate manner and the other positions being occupied by four water molecules, forming a distorted bicapped square antiprism. Two nitrate ions coordinate to the metal atom with similar bond lengths while the third shows a more asymmetric bonding behaviour. An intricate network of O—H⋯O hydrogen bonds, including the lattice water molecules, stabilizes the crystal packing.

Crystal structure of 2-(9H-fluoren-9-ylidene)hydrazine-1-carbothioamide, C14H11N3S

Abstract C14H11N3S orthorhombic, Pbcn (No. 60), Z = 8, a = 19.8130(12) Å, b = 8.1643(5) Å, c = 14.9521(9) Å, V = 2418.6(3) Å3, Z = 8, T = 100(2) K, GooF = 1.055, Rgt(F) = 0.0308, wRref(F2) = 0.0845.

The use of oil shale ash in the production of biodiesel from waste vegetable oil

Oil shale ash obtained from combustion of local oil shale deposits was used in this study as a heterogeneous catalyst to produce biodiesel from waste vegetable oil (WVO). Two alcohols with high and low boiling points, ethanol and ethylene glycol, were used for oil shale catalytic esterification of the WVO. Results show that the esterification of wastes of oil utilizing wastes of oil shale combustion can be used to produce biodiesel. Additionally, it was found that in order to make the oil shale ash an effective catalyst for transesterification, high reaction temperature is required. Therefore, the results have indicated that high biodiesel yield is obtained when using ethylene glycol at high temperature, while the yield is low when solid catalytic reaction is performed using ethanol at low temperature. The maximum obtained yield was 75 wt. % utilizing ethylene glycol at 150 °C, whereas this yield decreased to 69.9 wt. % as the operating temperature was reduced to 100 °C. On the other hand, when using ethanol, the yield of biodiesel was relatively low (11 wt. % at 60 °C and 9 wt. % at 80 °C).

Biodiesel production from waste soybean oil using jordanian oil shale ash

Biodiesel, an alternative diesel fuel derived from vegetable oil, animal fat, or waste vegetable oil (WVO), is obtained in this work by reacting waste vegetable soybean oil using oil shale ash as a heterogeneous catalyst in addition to two alcohols ethylene glycol and ethanol. Results have indicated that high biodiesel yield is obtained when using ethylene glycol at high temperature, while the yield is low when solid catalytic reaction is performed using ethanol at low temperature. This indicates that heterogeneous catalytic reaction is favored at a high temperature using alcohol with a high boiling point. Maximum yield was 75% wt using ethylene glycol at 150°C and the yield dropped to 69.9% wt as the operating temperature was reduced to 100°C. The increase in yield by 5% wt as the temperature increased from 100°C to 150°C is not significant. Using ethanol, the biodiesel yield is as low as 11% wt at 60°C and 9% wt at 80°C.