Ahmed K. Hijazi

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.

Heterogenization of a manganese(II) acetonitrile complex on AlMCM-41 and AlMCM-48 molecular sieves by ion exchange

An acetonitrile complex of composition [Mn(NCCH3)6][B(C6F5)4]2 (1) is grafted on Na-AlMCM-41/48 and H-AlMCM-41/48 by ion exchange. A metal loading of 0.25–0.6 wt% is achieved; the grafting of complex 1 is found to yield higher loading on Na-AlMCM-41/48 compared to H-AlMCM-41/48. Powder X-ray diffraction, N2 adsorption–desorption and TEM analysis of the grafted materials confirm the retention of long range ordering of the materials throughout the grafting process. FT-IR, EPR, TG-MS and elemental analyses confirm the successful grafting of the Mn(II) complex in the channels of the mesoporous materials, retaining the octahedral nitrile environment around the Mn2+ cation. The obtained materials are applied as heterogeneous initiators for the polymerization of isobutene.

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.

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.