Substituents effect on the spectral studies on rutheninum(III) complexes of 5(-4'-derivatives phenyldiazo)-3-phenyl-2-thioxo-4-thiazolidinone

Tautomeric transformations and electronic structures of azopyrazolone dyes and their metal complexes

The features of molecular and electronic structures of complex compounds derived from azopyrazolone derivatives are reviewed. Despite the wide use of metal-containing azopyrazolone dyes for more than 1.5 centuries, little information on their molecular structure is found. Our recent researches allowed the introduction of new coordination modes of azopyrazolone derivatives at complexation with metals. Together with traditional bi- and tridentate coordination, the possibility of an N pyrazolone atom to be involved in coordination was also found. As a result, polymeric or polynuclear complexes were isolated and described by X-ray analysis, NMR, EPR, IR, and UV spectroscopy. The analysis of the interatomic distances in the organic anions indicated that azopyrazolone derivatives do not undergo significant azo-hydrazo tautomeric transformations at ionization and complexation despite strong shifts of the absorption bands in their IR and UV-VIS spectra.

Coordination chemistry of pyrazine derivatives analogues of PZA: design, synthesis, characterization and biological activity

A novel Ru(iii) complexes were synthesized and characterized. Their stabilities were discussed in terms of aqueous and MeCN solutions. Antimicrobial properties of complexes studied were characterized against reference strains of bacteria and yeast.

Correlation between ionic radii of metal azodye complexes and electrical conductivity

5-(2,3-Dimethyl-1-phenylpyrazol-5-one azo)-2-thioxo-4-thiazolidinone (HL) and its metal complexes with copper(II) (1), cobalt(II) (2) and nickel(II) (3) are synthesized and characterized by physico-chemical techniques. The thermal properties of the ligand (HL) and its metal complexes (1-3) are discussed. The thermal activation energies of decomposition (Ea) of HL and its metal complexes with Cu(II), Co(II) and Ni(II) are found to be 48.76, 36.83, 30.59 and 40.45 kJ/mol, respectively. The frequency and temperature dependence of ac conductivity, dielectric constants for HL and its complexes (1-3) are investigated in the temperature range 300-356 K and frequency range 0.1-100 kHz. Both of the ac conductivity and the values of the thermal activation energy for conduction, as well as the dielectric properties of the complexes of HL are found to depend on the nature of the metallic ions. The values of the thermal activation energies of electrical conductivity decrease with increasing the value of test frequency. The small polarons tunneling (SPT) is the dominant conduction mechanism for the ligand (HL), while for complex (2) the overlapping large tunneling model (OLPT) is the dominant conduction mechanism. The correlated barrier hopping (CBH) is the dominant conduction mechanism for both of the complexes (1) and (3).

Correlation between ionic radii of metals and thermal decomposition of supramolecular structure of azodye complexes

An interesting azodye heterocyclic ligand of copper(II), cobalt(II), nickel(II) and uranyl(II) complexes have been synthesized by the reaction of metal salts with 5-(2,3-dimethyl-1-phenylpyrazol-5-one azo)-2-thioxo-4-thiazolidinone (HL) yields 1:1 and 1:2 (M:L) complexes depending on the reaction conditions. The elemental analysis, magnetic moments, spectral (UV-Vis, IR, (1)H and (13)C NMR and ESR) and thermal studies were used to characterize the isolated complexes. The molecular structures of the ligand tautomers are optimized theoretically and the quantum chemical parameters are calculated. The IR spectra showed that the ligand (HL) act as monobasic tridentate/neutral bidentate through the (-N=N), enolic (C-O)(-) and/or oxygen keto moiety groups forming a five/six-membered structures. According to intramolecular hydrogen bond leads to increasing of the complexes stability. The molar conductivities show that all the complexes are non-electrolytes. The ESR spectra indicate that the free electron is in dxy orbital. The calculated bonding parameter indicates that in-plane σ-bonding is more covalent than in-plane π-bonding. The coordination geometry is five/six-coordinated trigonal bipyramidal for complex (1) and octahedral for complexes (2-6). The value of covalency factor β1(2) and orbital reduction factor K accounts for the covalent nature of the complexes. The activation thermodynamic parameters are calculated using Coats-Redfern and Horowitz-Metzger methods. The synthesized ligand (HL) and its Cu(II) complexes (1, 2 and 4) are screened for their biological activity against bacterial and fungal species. The ligand (HL) showed antimicrobial activities against Escherichia coli. The ligand (HL) and its Cu(II) complexes (2 and 4) have very high antifungal activity against Penicillium italicum. The inhibitive action of ligand (HL), against the corrosion of C-steel in 2M HCl solution has been investigated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS).

Structural and characterization of novel copper(II) azodye complexes

The synthetic methods of novel Cu(II) and adduct complexes, with selective azodyes containing nitrogen and oxygen donor ligands have been developed, characterized and presented. The prepared complexes fall into the stoichiometric formulae of [Cu(L(n))(2)](A) and [Cu(L(n))(2)(Py)(2)](B), where two types of complexes were expected and described. In type [(A) (1:2)] the chelate rings are six-membered/four coordinate, whereas in type [(B) (1:2:2)] they are six-membered/six coordinate. The important bands in the IR spectra and main (1)H NMR signals are tentatively assigned and discussed in relation to the predicted assembly of the molecular structure. The IR data of the azodye ligands suggested the existing of a bidentate binding involving azodye nitrogen and C-O oxygen atom of enolic group. They also showed the presence of Py coordinating with the metal ion. The coordination geometries and electronic structures are determined from the framework of the proposed modeling of the formed novel complexes. The complexes (1-5) exist in trans-isomeric [N,O] solid form, while adduct complexes (6-10) exist in trans isomeric (Py) form. The square planar/octahedral coordination geometry of Cu(II)/adduct is made up of an N-atom of azodye, the deprotonated enolic O-atom and two Py. The azo group was involved in chelation for all the prepared complexes. ESR spectra show the simultaneous presence of a planar trans and a nearly planar cis isomers in the 1:2 ratio for all N,O complexes [Cu(L(n))(2)]. The ligands in the dimmer are stacked over one another. In the solid state of azo-rhodanine, the dimmers have inter- and intramolecular hydrogen bonds. Interactions between the ligands and Cu(II) are also discussed.

Polymer complexes: XLXII-interplay of coordination π-π stacking and hydrogen bonding in supramolecular assembly of [sulpha drug derivatives-N,S:N,O] complexes

A novel series of nickel(II) polymer complexes of 5-sulphadiazineazo-3-phenylamino-2-thio-4-thiazolidinone (HL₁), 5-sulphamethazine-3-phenylamino-2-thioxo-4-thiazolidinone (HL₂), 5-sulphamethoxazole-3-phenylamino-2-thioxo-4-thiazolidinone (HL₃), 5-sulphacetamide-3-phenyl-2-thioxo-4-thiazolidinone (HL₄) and 5-sulphaguanidine-3-phenylamino-2-thioxo-4-thiazolidinone (HL₅) were prepared and characterized. IR spectra show that HL(n) (n=1-5) is coordinated to the metal ion in a neutral tetradentate manner with NSNO donor sites of NH (hydrazone's), NH (3-phenylamine), carbonyl group and Ph-NH. The title [Ni₃(HL(n))₂(μ-OAc)₂(OAc)₄](n) consists of three Ni(II) atoms linked by interchain π-π interaction are observed between aromatic rings of two ligands (HL(n)) which are further doubly bridged two adjacent nickel atoms by acetate group. The geometrical structures of these complexes are found to be octahedral. The nature of bonding and the stereochemistry of the complexes have been deduced from elemental analyses, thermal, infrared, ¹H NMR, electronic spectra, magnetic susceptibility and conductivity measurements. The richness of electronic spectral in these complexes is also supporting evidence for the trinuclearity of the Ni(II) polymer complexes.

Synthesis, characterization, and biological activity of N-methyl-2-(1H-1,2,3-benzotriazol-1-y1)-3-oxobutan- ethioamide complexes with some divalent metal (II) ions

A new series of Zn²⁺, Cu²⁺, Ni²⁺, and Co²⁺ complexes of N¹-methyl-2-(1H-1,2,3-benzotriazol-1-yl)-3-oxobutanethioamide (MBOBT), HL, has been synthesized and characterized by different spectral and magnetic measurements and elemental analysis. IR spectral data indicates that (MBOBT) exists only in the thione form in the solid state while 13C NMR spectrum indicates its existence in thione and thiole tautomeric forms. The IR spectra of all complexes indicate that (MBOBT) acts as a monobasic bidentate ligand coordinating to the metal(II) ions via the keto-oxygen and thiolato-sulphur atoms. The electronic spectral studies showed that (MBOBT) bonded to all metal ions through sulphur and nitrogen atoms based on the positions and intensity of their charge transfer bands. Furthermore, the spectra reflect four coordinate tetrahedral zinc(II), tetragonally distorted copper(II), square planar nickel(II), and cobalt(II) complexes. Thermal decomposition study of the complexes was monitored by TG and DTG analyses under N₂ atmosphere. The decomposition course and steps were analyzed and the activation parameters of the nonisothermal decomposition are determined. The isolated metal chelates have been screened for their antimicrobial activities and the findings have been reported and discussed in relation to their structures.

Polymer complexes: XLIX-Supramolecular modeling of bonding in novel rare earth polymeric rhodanine drug complexes

Novel supramolecular rare earth polymeric hydrazone complexes of 5-sulphadiazineazo-3-phenyl-2-thiaxo-4-thiazolidinone (HL) of the composition [(Ln)(2)(HL)(3)(NO(3))(6)](n) (where Ln = La(1), Y(2), Pr(3), Nd(4), Sm(5), Gd(6) and Ho(7)) have been prepared and characterized on the basis of their chemical analyses, magnetic measurements, conductance, visible and IR spectral data. Composition, conductance and IR spectral data of complexes show that all these act as a tetradentate ligand. Electronic spectra indicate weak covalent character in the metal-ligand bond. The spectra of Nd(3+) and Ho(3+) show characteristic f-f transitions and the metal-ligand covalency in % has been evaluated. The spectral properties of the above polymeric complexes are also discussed.

Minimally Destructive Analysis of Aluminum Alloys by Resonance-Enhanced Laser-Induced Plasma Spectroscopy

Aluminum alloys were analyzed for minor components and trace impurities using double pulse resonance-enhanced laser-induced plasma spectroscopy. The first laser pulse at 532 nm ablated the sample. The second laser pulse at 396.15 nm resonantly excited the Al atoms to rekindle the plasma plume. Emissions from Mg, Cu, Si, and Na were observed. At laser energies below the damage threshold, the analyte emissions were already orders of magnitude above the background noise. Nonresonant probes of comparable sensitivity would melt and deform the sample surface. Because of the lower etch rate of resonant probes, depth profiling at nanometer resolution was possible. Using this method, the variation of [Na] with depth was measured for high-purity samples. In contrast, nonresonant probes required 5 times the fluence and proportionally poorer resolution. Worse yet, the associated heating and laser remelting modified the [Na] profile.

Polymer complexes. XXXX. Supramolecular assembly on coordination models of mixed-valence-ligand poly[1-acrylamido-2-(2-pyridyl)ethane] complexes

The build-up of polymer metallic supramolecules based on homopolymer (1-acrylamido-2-(2-pyridyl)ethane (AEPH)) and ruthenium, rhodium, palladium as well as platinum complexes has been pursued with great interest. The homopolymer shows three types of coordination behaviour. In the mixed valence paramagnetic trinuclear polymer complexes [(11)+(12)] in the paper and in mononuclear polymer complexes (1)-(5) it acts as a neutral bidentate ligand coordinating through the N-pyridine and NH-imino atoms, while in the mixed ligand diamagnetic poly-chelates, which are obtained from the reaction of AEPH with PdX2 and KPtCl4 in the presence of N-heterocyclic base consisting of polymer complexes (9)+(10), and in monouclear compounds (6)-(8), it behaves as a monobasic bidentate ligand coordinating through the same donor atoms. In mononuclear compounds (13)+(14) it acts as a monobasic and neutral bidentate ligand coordinating only through the same donor atoms. Monomeric distorted octahedral or trimeric chlorine-bridged, approximately octahedral structures are proposed for these polymer complexes. The poly-chelates are of 1:1, 1:2 and 3:2 (metal-homopolymer) stoichiometry and exhibit six coordination. The values of ligand field parameters were calculated. The homopolymer and their polymer complexes have been characterized physicochemically.