Azza E.H. Abdou

Spectral and structural characterization of trans-dibromobis(2-benzoylpyridine)copper(II) and trans-diazidobis(2-benzoylpyridine)copper(II) [CuX2(2-benzoylpyridine)2] (X = Br or N3)

Abstract Complexes of copper(II) bromide and copper(II) azide with 2-benzoylpyridine (2-Bzpy), namely trans-dibromobis(2-benzoylpyridine)copper(II) (1) and trans-diazido-bis(2-benzylpyridine)copper(II) (2), have been prepared and characterized by spectroscopic methods and X-ray crystallography. The copper atom in centrosymmetric [CuBr2(2=-Bzpy)2] (1) is six-coordinated by two nitrogen atoms [CuN = 1.970(4) A] and two oxygen atoms [CuO = 2.407(4) A] belonging to the two 2-Bzpy molecules and two trans-bromide atoms at CuBr distances of 2.468(1) A. In the structure of complex 2, [Cu(N3)2(2-Bzpy)2], the copper atom which is also located at an inversion centre is six-coordinated by pairs of trans-N,O-bidentate chelating 2-Bzpy molecules [CuN = 2.005(3) A, CuO = 2.467(3) A] and the terminal azido ligands at CuN distances of 1.989(4) A. The azido ligands are almost linear [NNN = 176.6(4)°] and asymmetric [NαNβ = 1.201(5) and NβNγ = 1.158(5) A]. The IR and electronic spectral data for both complexes are presented and discussed.

INTRAMOLECULAR OXIDATIVE CYCLIZATION OF 2-BENZOYLPYRIDINE AND STRUCTURAL CHARACTERIZATION OF [9-OXO-INDOLO[1,2-A]PYRIDINIUM] COPPERDIIODIDE AND [Di-μ-bromo-bis(2-BENZOYLPYRIDINE)DICOPPER(I)]

Abstract When a mixture of excess Cu(I)I and 2-benzoylpyridine (2-Bzpy) stands in an ethanolic medium for two weeks, an intramolecular oxidative cyclization of 2-Bzpy occurs with formation of the ionic complex [(9-oxo-indolo[1,2-a]pyridinium]+ · CuI2 −(1). In contrast the interaction of Cu(I)Br and 2-Bzpy in ethanol leads to formation of the dimer [CuBr(2-Bzpy)]2 (2). The structures of both compounds were established by spectroscopic methods and X-ray diffraction analysis: (1) Space group P21/a,a = 6.613(2), b = 16.792(5), c = 12.062(5) A, B = 94.35(3)° and Z = 4, (2) Space group P21/n, a = 6.896(2), b = 7.551(2), c = 22.454(4) A, B = 93.34(2)° and Z = 4. The structure of (1) consists of a packing of [9-oxo-indolo[1,2-a]pyridinium]+ cations and CuI2 − species with the four Cu[sbnd]I distances varying from 2.669(2) to 2.705(2) A. The centrosymmetric [CuBr(2-Bzpy)]2 (2) molecule has a short Cu[sbnd]Cu distance of 2.696(2) A.

Synthesis and characterization of copper(I) halide/pseudohalide adducts of 2-benzoylpyridine and X-ray crystal structure of [di-μ-iodo-bis(N,O-2-benzoylpyridine)dicopper(I)]

Abstract Dark-brown copper(I) complexes of the type CuXL, for X = Cl, Br, I, SCN and N3, and orange-yellow complexes of the type (CuX)2L, for X = Cl or Br, where L = 2-benzoylpyridine, have been prepared and characterized. All complexes exhibit strong CT bands in the visible region and gave non-conducting solutions in acetone and nitrobenzene. The IR spectral data suggest that 2-benzoylpyridine acts as a monodentate ligand in the orange-yellow complexes and as a bidentate chelating ligand in the brown complexes, whereas bridging halides and pseudohalides exist in both types. The structure of the 1 : 1 black iodide complex, as determined by X-ray crystallography, features a discrete, centrosymmetric [CuI(2-benzoylpyridine)]2 molecule with a short Cu⋯Cu distance of 2.587(1) A. Each copper atom in the dimeric molecule is tetrahedrally coordinated by two μ-iodine atoms and the carbonyl oxygen and nitrogen atoms of the chelating 2-benzoylpyridine ligand. The orange-yellow complexes display visible emission when excited in the UV region, whereas the brown complexes do not.

Preparation and characterization of gold(III) halide complexes of picolinic acid (pic-H) and X-ray crystal structure of [K(pic-H)2(H2O)2][AuBr4]·(pic-H)2

Abstract Complexes of the types MAuX4·4(pic-H)·2H2O (M = Na for X = Cl and M = K for X = Br), NaAu(pic)2K2·2H2O (where X = Cl or I) and NaAuCl4·Na(pic-H)·(pic)·2H2O (where pic-H = picolinic acid) have been prepared and characterized. Picolinic acid functions as a neutral N,O-bidentate ligand in the first type and as an O-monodentate picolinate anion in the second type. The IR results suggest that the last complex contains both neutral and anionic organic moieties. The conductivities of these complexes were measured and are discussed. X-ray single-crystal analysis of the KAuBr4 · 4(pic-H)·2H2O complex revealed that it should be formulated as [K(pic-H)2(H2O)2]·[AuBr4]·(pic-H)2. The potassium atom in the centrosymmetric cation is octahedrally coordinated by two trans-N,O-bidentate neutral picolinic acid molecules [KN = 2.790(6) A and KO = 2.888(5) A] and two aqua ligands at KO distances of 2.769(4) A. The other two picolinic acid molecules are involved in hydrogen bonding with the oxygen atoms of the coordinated pic-H and aqua molecules.

Enhanced removal of lead and cadmium from water by Fe3O4-cross linked-O-phenylenediamine nano-composite

ABSTRACT A method is presented for surface encapsulation of nano-Fe3O4 by o-phenylenediamine via cross-linking using formaldehyde and glutaraldhyde for the formation of two newly designed magnetic nano-sorbents. These have been characterized by FT-IR, TGA, and SEM and maintained the magnetic and thermal stability characters. The metal capacity values of Pb(II) and Cd(II) have been optimized in presence of different physico-chemical parameters and confirmed the superior selectivity for Pb(II). Maximum capacity values of Pb(II) (7000-10000 ± 250-675 µmol g−1) and Cd(II) (1500-2250 ± 30-75 µmol g−1) at optimum conditions and excellent extraction values (94.10-100.0 ± 1.2-3.5%) from industrial wastewater have been identified.

Bis-(tetraethylammonium)[tetraazidocuprate(II)] and catena-di-μ-1,1-azido-[di-μ-1,1-azido-bis-(2,4-dimethylpyridine)dicopper(II)]

Two new copper(II) azido complexes, namely bis-(tetraethylammonium)[tetraazidocuprate(II)] (1) and catena-di-μ-1,1-azido-[di-μ-1,1-azido-bis-(2,4-dimethylpyridine)dicopper(II)] (2), have been prepared and characterized by spectroscopic and crystallographic methods. Complex (1) consists of isolated NEt+4 cations and [Cu(N3)4]2− anions. The site symmetry around the copper atom in the anion is 4/m. Complex (2) features a 1 D chain structure, five coordinated square pyramidal copper(II) atoms with both azides functioning as μ-1,1-bridges. The i.r. spectra reveal that both complexes contain asymmetric azido ligands. The solid and solution electronic spectra of (1) and (2) show very strong absorption bands in the visible region associated with N−3 → CuII charge-transfer transitions. The e.p.r. spectra of powder samples and solutions at room temperature were recorded and discussed.

Solid–solid crosslinking of carboxymethyl cellulose nanolayer on titanium oxide nanoparticles as a novel biocomposite for efficient removal of toxic heavy metals from water

Nano titanium oxide (Nano-TiO2) was used in this work as a solid support to solid-solid immobilize carboxymethyl cellulose via glutaraldehyde as an efficient cross linking reagent to produce a novel nanosized biocomposite (Nano-TiO2-glu-CMC). The synthesized materials were characterized by FT-IR to confirm crosslinking reaction between the two species as well as by HR-TEM, SEM, TGA and surface area analysis. The particle size was found to correspond to 22.2-44.4nm for Nano-TiO2-glu-CMC. The designed nanosized biocomposite was used and compared with Nano-TiO2 for separation and extraction of heavy metal ions such as Cd(II), Pb(II) and Hg(II) from aqueous solution by using batch experiment and microcolumn technique. The maximum metal sorption capacity values of Cd(II), Pb(II) and Hg(II) were established as 2440μmolg-1 (pH 7), 2880μmolg-1 (pH 6) and 1160μmolg-1 (pH 3), respectively. Optimization of the extraction experiments confirmed the maximum adsorption upon using 0.025g biocomposite dosage and 30min contact time.