Angela Kriza

Synthesis, spectral characterization, and thermal behavior of mononuclear Cu(II), Co(II), Ni(II), Mn(II), and Zn(II) complexes with 5-bromosalycilaldehyde isonicotinoylhydrazone

A bidentate/tridentate 5-bromosalycilaldehyde isonicotinoylhydrazone Schiff base was synthesized by condensing 5-bromosalycilaldehyde with isonicotinoylhydrazine. Cu(II), Co(II), Ni(II), Mn(II) and Zn(II) complexes of this chelating ligand were synthesized using nitrates of these metals. The ligand and the complexes were characterized by elemental analysis, UV–Vis, IR and EPR spectroscopy, conductance and magnetic susceptibility measurements, fluorescence, cyclic voltammetry and thermogravimetric analysis. The ligand and Zn(II) complex exhibits solid-state photoluminescence at room temperature.

Synthesis and structural studies of complexes of Cu, Co, Ni and Zn with isonicotinic acid hydrazide and isonicotinic acid (1-naphthylmethylene)hydrazide

Eight new complexes of Cu(II), Co(II), Ni(II) and Zn(II) with isonicotinic acid hydrazide (isoniazid, (INH)) and isonicotinic acid (1-naphthyl-methylene)hydrazide (INNMH), having the formula of the type [M(INH)(ac)(2))] or [M(INNMH)(ac)(2)] (M = Co(II), Ni(II) and Zn(II)) and [Cu(INH)(ac)(2)](2), [Cu(INNMH)(ac)(2)](2), were synthesized and characterized. All complexes were characterized based on elemental analyses, and IR, UV-VIS-NIR and EPR spectroscopy, as well as by thermal analysis and determination of their molar conductivity and magnetic moments. The structure of INNMH was established by single crystal X-ray analysis. In all complexes, both ligands were coordinated to the metal via N and O. The complexes of Cu (II) were dimeric, with four bridges between acetate ions and Cu(II).

Spectral, magnetic and thermal characterisation of new Co(II), Ni(II) and Cu(II) complexes with Schiff base 5-bromo-N,N′-bis-(salicylidene)-o-tolidine

Starting from 5-bromo-N,N′-bis-(salicylidene)-o-tolidine (H2L) new complexes with Co(II), Ni(II) and Cu(II) were synthesised and characterised. The features of complexes have been assigned from microanalytical, IR, UV–Vis–NIR and EPR spectra, magnetic data at room temperature as well as thermal analysis. IR data are in accordance with bischelate nature of the deprotonated ligand that coordinates through azomethinic nitrogen and phenolic oxygen. The electronic spectra display the characteristic pattern of tetrahedral stereochemistry for [CoL]·H2O complex and octahedral one for [NiL(OH2)2]·H2O complex. The electronic spectra correlated with magnetic susceptibility measurements indicate a square-planar surrounding for [ML] (M:Ni, Cu) species, while the EPR spectrum of copper complex sustains the proposed stereochemistry. The thermal analysis evidenced that thermal transformations are complex processes according to TG, DTA and DTG curves including (crystallization or coordination) water elimination, thermolyses and oxidative degradation of Schiff base. All these processes lead to the most stable metallic oxides as final product.

Synthesis and structural studies of Co(II), Ni(II) and Cd(II) complexes with 2-acetylpyridine

Three new mononuclear complexes [Co(2-Acpy)2(H2O)2](NO3)2 (1), [Ni(2-Acpy)2(H2O)2](NO3)2 (2) and [Cd(2-Acpy)2(NO3)2] (3) (2-Acpy = 2-acetylpyridine) have been synthesized and characterized by elemental analysis, IR and UV–Vis spectroscopy. The structures of 1 and 3 were accomplished by single crystal X-ray diffraction. Crystallographic investigation of 1 reveals monomeric, dicationic units in which the cobalt(II) ion is six-coordinate. The coordination sphere is formed by two N, O bidentate acetylpyridine ligands and two water molecules. The crystal structure of 3 consists of monomeric units in which the cadmium is eight-coordinate. Both the organic ligand and nitrate groups are bidentate chelators. The supramolecular solid-state architecture is sustained by π–π interactions.

New complexes with 2-pyridyl ketone Schiff bases

Seven new complexes of 2-pyridyl ketone Schiff bases N,N′-bis-(pyridin-2-yl-benziliden)-propan-1,3-diamine (bpbpd) and N,N′-bis-[1-(pyridin-2-yl)-etiliden]-propan-1,3-diamine (bpepd) with Co(II), Ni(II), Zn(II) and Cd(II) nitrates and perchlorates were synthesized and investigated using elemental analysis, spectroscopic techniques (IR and UV–Vis–NIR) as well as magnetic and conductometric measurements. The structure of a cadmium(II) complex was accomplished by single-crystal X-ray diffraction. The Schiff base ligands act as NNNN tetradentate ligands coordinating through pyridine nitrogens and azomethine nitrogens to transition metal ions. The metal ions are six-coordinate for Co(II) and Ni(II), four-coordinate in the case of Zn(II) and eight-coordinate for Cd(II) ions. The coordination sphere of cobalt and nickel complexes is completed by two water molecules, resulting a distorted octahedron. In the case of zinc(II) complexes has been proposed a distorted tetrahedral geometry. The Cd(II) ions are surrounded by a tetradentate Schiff base ligand and two bidentate nitrate anions, leading to a dodecahedral coordination environment. Thermal decomposition of these compounds is a multistage process. Generally, water elimination occurs in the first step and the decomposition of nitrate groups and organic ligands in the next stages. The last step of decomposition for all complexes is strong exothermic and corresponds to oxidative combustion of the Schiff base ligand.

Synthesis and crystal structure of a new one-dimensional cadmium(II)–azide system with phenyl-2-pyridyl ketone

A new one-dimensional (1-D) cadmium(II) complex [Cd(ppk)(N3)2] n (1) has been synthesized and characterized. X-ray crystal structure study reveals that 1 is composed of a 1-D cadmium(II) chain with double µ1,1 azido bridges. Three different cadmiums, Cd(1), Cd(2), and Cd(3), may be found along the chain.

Metal(II) Nitrate Complexes with Phenyl-2-Pyridil-Ketone: Synthesis, Characterization and Antibacterial Activity

Four new mononuclear complexes having general formulae [M(ppk)2(H2O)2](NO3)2 (M═Co (1); M═Ni (2); M═Zn (3)) and [M(ppk)2(NO3)2] (4) (ppk = phenyl-2-pyridil-ketone) have been synthesized and characterized by elemental analysis, IR and UV-vis spectroscopy. The structures of 3 and 4 were accomplished by single crystal X-ray diffraction. The crystallographic investigation of 3 reveals monomeric, dicationic units in which the zinc(II) ion is six-coordinated. The coordination sphere is formed by two N, O bidentate phenyl-2-pyridil-ketone ligands and two water molecules. The crystal structure of 4 consists of monomeric units in which the cadmium atom is eight-coordinated. Both the organic ligand and nitrate groups are bidentate chelators. Biological activity studies reveal a moderate activity of complexes against Gram negative and Gram positive bacteria.

Metal Based Sulfides, p-Type Semiconductors in Solid State Solar Cells

The paper present the research made in obtaining of dense, homogeneous and relative uniform thin films of CuxS and SnS with specific structural and electrical properties, as p-type semiconductors and absorbers for solid state solar cells. The films are deposited via spray pyrolysis deposition (SPD), and analyzed by XRD, SEM and dark I-V curves