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The experimental protonation and complex formation equilibrium constants of nicotine (NIC) with trivalent (iron (III), and chromium (III)) and divalent (copper (II), and nickel (II)) metal ions have been investigated at 310.15 oK in water solutions at ionic strength of 13.60 g·dm−3 NaNO3 using pH-potentiometric and cyclic voltammetry techniques, and by means of Hyperquad 2008 estimation model program. Also, the dissociation constants of NIC and the equilibrium constants of its binary complexes with the studied metal ions in 13.60 g·dm−3 NaNO3 water solutions were observed at different temperatures such as (298.15, 310.15, 318.15 and 328.15) K. The theoretical calculations of overall protonation and stability constants of the metal ion-nicotine complex species in aqueous solutions were predicted as the Gibbs energy change associated with the nicotine protonation, and metal ion – nicotine complex formation equilibria using ab initio and density function theory calculations by applying Gaussian 09 software molecular modeling. The usage of the experimental potentiometry/spectrophotometry techniques and theoretical predictions provides a complete picture of the microscopic equilibria of the studied systems (metal ions -nicotinate). Precisely, this theoretically predications could be useful to control the most real protonation constants of nicotine ligand in which the binding sites changes due to the ligand protonation/deprotonation equilibria. Also, the complexing capacities of different metal ions towards nicotine in solutions were evaluated and discussed. From the determined experimental stability constants of different metal complex species, the concentration distribution diagrams of the various metal ions - nicotine complex species in solutions were estimated using HySS 2009 software.

Platinum(II) and vanadium(V) solid binary and ternary complexes involving naringin, a flavanone glycoside in found in grapefruit, and some phenolic acids were synthesized and fully characterized using detailed structural and spectroscopic analysis techniques such as IR, NMR, and SEM techniques. The magnetic susceptibility results as well line drawings of the platinum and vanadium complexes showed four-coordinate square-planar and remarkable low-spin diamagnetic species; which is in agreement with the structures proposed. The cytotoxic activities of the binary and ternary vanadium and platinum metal complexes of phenolic acids and naringin were tested and evaluated against HepG2 (human hepatocellular carcinoma), MCF-7 (human breast adenocarcinoma), and HCT116 (human colorectal carcinoma) tumor cell lines. Also, their antioxidant activities were examined by free radical scavenging assay. The relationship between the chemical structure of the synthesized complexes and their biological influence was studied and evaluated.

The Experimental thermodynamic equilibrium (pKa values) and stability (log β) constants of vanadium and platinum binary and mixed ligand complexes involving naringenin, ferulic acid, p-coumaric acid, caffeic acid, vanillic acid, sinapic acid, and gallic acid were determined at 310.15 K in 0.16 mol·dm−3 KCl aqueous solutions using pH-potentiometric technique and by means of two estimation models (HYPERQUAD 2008 and Bjerrum–Calvin). The theoretical calculations of overall protonation and stability constants of the metal complex species in solution were predicted as the free energy change associated with the ligand protonation, and metal ion–ligand complex formation equilibria (species solvation/de-solvation) using ab initio and density function theory (DFT) calculations. The usage of the experimental potentiometry technique and theoretical predictions provides a complete picture of the microscopic equilibria of the studied systems (vanadium/platinum–naringenin–phenolic acid). Specifically, this theoretically DFT predications would be useful to determine the most real protonation constants of the studied bioligands in which the binding sites changes due to the ligand protonation/deprotonation equilibria. Also, the complexing capacities of vanadium and platinum towards naringenin, ferulic acid, p-coumaric acid, caffeic acid, vanillic acid, sinapic acid, and gallic acid in solutions were evaluated and discussed. From the determined experimental stability constants of different metal complex species, the concentration distribution diagrams of the various metal ion complex species in solution was estimated using HySS 2009 software.

Four siderophore analogues were isolated and purified from Escherichia coli, Bacillus spp. ST13, and Streptomyces pilosus microorganisms under some specific submerged fermentation conditions. In order to evaluate the highest production of this siderophore analogues through the growth, a rapid spectrophotometric screening semi-quantitative method was used, in which interestingly the analogues were isolated in its own form not its iron chelate. After chromatographic separation, the chemical structures of the isolated and purified siderophores were illustrated using detailed spectroscopic techniques. The biodegradation studies were done on that four novel isolated and purified siderophores following OECD protocols. In addition, the bioactivities of these siderophores and their iron complexes were examined and evaluated.

The interaction of a number of divalent and trivalent metal ions [iron(III), chromium(III) copper(II), cobalt(II) and nickel(II)] with four isolated and purified microbial catecholate and hydroxamate siderophores was studied using the pH-potentiometric technique to investigate the complexation behavior of these systems as these systems could mimic many biological interactions of the siderophore chelating agent. The protonation constants of these new siderophore analogues as well their binary complex species stability constants were determined using the Hyperquad 2008 estimation model program. From the determined stability constants of the metal complex species, the concentration distribution of the various metal ion complex species involving isolated siderophore analogues in solutions was estimated using the HySS 2009 modeling program. The complex species distribution diagrams were plotted and discussed. Additionally, the Gibbs energies and the molecular structures of the formed complex species were evaluated and predicted using Gaussian 09 software for molecular modeling and density functional theory calculations.

Silver oxide nanoparticles of various sizes (5–40 nm) have been successfully prepared by sonochemical, solvothermal and microemulsion methods. X-ray diffraction studies reveal the high phase purity of silver oxide nanoparticles with cubic and hexagonal symmetries. Transmission electron microscopic studies show the formation of spherical silver oxide nanoparticles (5–8 nm) using sonochemical and solvothermal methods, however, microemulsion method results in the formation of non spherical silver oxide nanoparticles (10–40 nm). UV–Visible spectroscopy shows the band appearance at 400 nm and 420 nm which correspond to the surface plasmon resonance of silver in silver oxide nanoparticles. Surface area studies give the surface areas of 19.7 m2/g and 12.6 m2/g using the sonochemical and solvothermal methods respectively. Where as surface area of 29.5 m2/g and 13.3 m2/g were obtained for the silver oxide nanoparticles prepared by the microemulsion method using Tergitol and Triton X-100 as the surfactants, respectively.

Broadband amplifier emission near the second telecommunication window in Ho 3+ doped 76TeO 2 ·10ZnO·9.0PbO·1.0PbF 2 ·3.0Na 2 O was studied. The optical transition properties and radiative lifetimes of several excited states of Ho 3+ have been predicted using intensity Judd–Ofelt parameters. The emission cross section for Ho 3+ in this glass, around 2 μm, was calculated according to McCumber theory. The maximum stimulated emission cross section was calculated to be 0.9 × 10 −20 cm 2 for 2046 nm emissions. The theoretical gain cross sections was evaluated and positive gain bands was anticipated. Furthermore, the peak Raman gain coefficient in the present glass was around 250 times larger than that of SiO 2 .

We report here the synthesis of nickel oxide (NiO) nanoparticles by microwave-assisted method, using a common precipitating agent followed by calcination at 400 °C. The effect of the microwave and pH on the crystallite size, morphology, structure, energy band gap and surface area of NiO have been investigated by means of powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet visible spectroscopy (UV–vis) and BET surface area studies. It was observed that on increasing the volume of NaOH, the optical band gap energy (2.85–2.95 eV) and specific surface area (33.1–39.8 m2/g) increases, however the average particles size decreases (16.5–14 nm).

Novel ball-in-ball hollow CuO microspheres have been synthesized by a one-step microwave-assisted process in mere 10 min without any surfactant. The as-prepared product shows uniform spherical morphology with diameters of 2.5–4 μm. The shell thickness of the outer and inner balls is around 200 and 460 nm, respectively, and the spacing between the two shells is about 150 nm. The formation mechanism for the ball-in-ball CuO architectures has been discussed. When evaluated as an enzyme-free sensor, the ball-in-ball CuO microspheres display an excellent electrocatalytic response to H 2 O 2 with the advantages of good sensitivity, short response time, and low detection limit.

Gold nanoparticles have been successfully synthesized by solvothermal method using SnCl 2 and NaBH 4 as reducing agents. X-ray diffraction studies show highly crystalline and monophasic nature of the gold nanoparticles with face centred cubic structure. The transmission electron microscopic studies show the formation of nearly spherical gold nanoparticles of average size of 15 nm using SnCl 2 , however, NaBH 4 produced highly uniform, monodispersed and spherical gold nanoparticles of average grain size of 7 nm. A high surface area of 329 m 2 /g for 7 nm and 269 m 2 /g for 15 nm gold nanoparticles was observed. UV–vis studies assert the excitations over the visible region due to transverse and longitudinal surface plasmon modes. The gold nanoparticles exhibit excellent size dependant antifungal activity and greater biocidal action against Candida isolates for 7 nm sized gold nanoparticles restricting the transmembrane H + efflux of the Candida species than 15 nm sized gold nanoparticles.

The academic and industrial research on the interactions of complexing agents with the environment has received more attention for more than half a century ago and has always been concerned with the applications of chelating agents in the environment. In contrast, in recent years, an increasing scholarly interest has been demonstrated in the chemical and biological degradation of chelating agents. This is reflected by the increasing number of chelating agents-related publications between 1950 and middle of 2016. Consequently, the discovery of new green biodegradable chelating agents is of great importance and has an impact in the non-biodegradable chelating agent’s replacement with their green chemistry analogs. To acquire iron, many bacteria growing aerobically, including marine species, produce siderophores, which are low-molecular-weight compounds produced to facilitate acquisition of iron. To date and to the best of our knowledge, this is a concise and complete review article of the current and previous relevant studies conducted in the field of production, purification of siderophore compounds and their metal complexes, and their roles in biology and medicine.

We have grown large-scale well-aligned ZnO nanorods/nanowires on commercial flexible graphite sheet (FGS) at low temperature via chemical vapor deposition method. The products were characterized by X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy. The effects of the growth temperature and oxygen flow rate on the morphology of ZnO nanostructures have been investigated. The growth mechanism of ZnO is found to be a self-catalytic vapor–solid process assisted by the immiscibility of ZnO with graphite. The as-grown ZnO/FGS products show strong green emission and their photoluminescence properties can be tuned by changing growth condition or annealing treatment.

Well dispersed nickel oxide nanoparticles have been synthesized successfully by direct calcination of nickel linoleate. The structure, morphology and properties of the nanoparticles were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy and ultraviolet–visible spectroscopy. Transmission electron microscopic studies show that nickel oxide nanoparticles are uniform with an average size of 14–20 nm. The optical band gap of 3.8 eV is obtained using UV–Visible spectroscopy which exhibits the red shift compared with the bulk counterpart.

Waste tire powder, as waste rubber WR was subjected to grafting with styrene (St) and maleic anhydride (MA). Hydrogen peroxide H2O2 was used to initiate the free radical copolymerization of St onto WR. A thermal initiation was used in case of grafting of MA onto WR. Effect of initiator and monomer concentrations together with the influence of reaction temperature and reaction time were investigated. The grafting was estimated by weight, and the grafted copolymers were characterized by FT/IR, DSC and SEM to prove the grafting. It has found that the grafting increases with increase monomer and initiator concentrations. The increase in the reaction temperature and time also causes increasing levels of the grafted St and MA.

Spherical NiO nanoparticles have been synthesized by a simple and modified solvothermal method using NiCl2·6H2O and urea. After the precursor was calcined in the air, NiO could be obtained. Structural, optical, and morphological characterizations were done by x-ray powder diffraction, ultraviolet–visible (UV–vis) spectroscopy, and scanning electron microscopy. Fourier-transform infrared (FTIR) studies show a broad absorption around 422–425 cm−1 corresponding to a surface-active mode, indicating the nanocrystalline nature of the oxide. The values of some important physical parameters of material are determined, such as refractive index (n), dielectric constant (ϵ), ratio of molar volume (Vm) and molar refraction (Rm), and metallization criterion (M(n)).

The proton−ligand dissociation constant of vanillin (4-hydroxy-3-methoxy benzaldehyde) and metal−ligand stability constants of its complexes with metal ions (Mn2+, Co2+, Ni2+, Cu2+, and Zn2+) have been determined potentiometrically in 0.1 mol·dm−3 KCl and 10 % (by volume) ethanol−water mixture and at (298, 308, and 318) K. The stability constants of the formed complexes increase in the order Mn2+, Co2+, Ni2+, Zn2+, and Cu2+. The effect of temperature was studied, and the corresponding thermodynamic parameters (ΔG, ΔH, and ΔS) were derived and discussed. The dissociation process is nonspontaneous, endothermic, and entropically unfavorable. The formation of the metal complexes has been found to be spontaneous, endothermic, and entropically favorable.

Novel complexes of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II) and UO2(II) with a new Schiff base derived from 8-hydroxy-7-quinolinecarboxaldehyde and 2-aminoethanethiol (LH2) (system name: 2-(8-hydroxy-7-carboxalimino)ethanethiol.) have been prepared and characterized on the basis of analytical, thermal, magnetic moment, infrared, electronic, NMR and EPR spectral data. From the analytical, NMR and thermal data and stoichiometry of the complexes indicate that LH2 act as a dibasic tridentate ligand with ONS donors towards all the metal ions. The magnetic moment, electronic and EPR spectral data commensurate that the Mn(II), Fe(II), Ni(II) and UO2(II) complexes are dimeric with octahedral configuration while the Cu(II) and Zn(II) complexes are monomeric with square-planar and tetrahedral geometries, respectively. Various ligand field parameters Dq, B and β for complex 5 was calculated. The complexes 3 + 4 have lower symmetries and the amount of distortion in terms of DT/DQ applying NSH “Hamiltonian Theory” has been evaluated which indicate that the complexes are moderately distorted.

Polymer complexes derived from cinnamaldehyde and 2-substituted aniline with Cu(II), Pd(II), Pt(II), UO2(II), Rh(III), Ru(III), and Pd(IV) have been synthesized and characterized by IR, electronic, EPR, 1H-NMR, and 13C-NMR spectra, as well as by elemental analysis, thermogravimetry, and magnetic susceptibility measurements. The important bands in the IR spectra and the main 1H- and 13C-NMR signals are assigned and discussed in relation to molecular structure. The wavelengths of the principal electronic absorption peaks have been accounted for quantitatively in terms of crystal field theory and various parameters were evaluated. The complexes, [Ru(HL n )Cl3] n , are penta-coordinate; and, a trigonal-bipyramidal environment is commensurate for the Ru(III) ion. The presence of a coordinated water molecule in complex the Cu(II) complex (20) was demonstrated by thermogravimetry. The compounds, [N-(3-phenylacrylidene)-2-mercaptoaniline] (HL1) and cinnamaldehyde-2-aminophenol (HL2), act as monobasic and neutral bidentate ligands. The B-value suggests a strong covalency in the metal-ligand σ-bond. Tentative structures of the polymer complexes are proposed.

Mono, bis- and tris-polymer complexes of ruthenium(III) and rhodium(III) chloride with 3-hydroxy-2-N-acrylamidopyridine (H2L) monomer, derived from amidation of acryloyl chloride with 2-amino-3-hydroxypyridine, have been prepared. A few bimetallic mixed ligand polymer complexes have also been obtained by the reaction of rhodium(II) bidentate poly-chelate mixed ligand with palladium(II), platinum(II) or zirconium(IV) chlorides and uranyl acetate. These polymer complexes have been characterized on the basis of their elemental analysis, magnetic susceptibility, electronic and infrared spectral data and thermal analysis. The homopolymer shows three types of coordination behavior. The poly-chelates are of 1 : 1, 1 : 2 and 1 : 3 (metal : homopolymer) stoichiometry and exhibit six coordination. Electronic spectra show all complexes are octahedral. The spectral data were utilized to complete the important ligand field parameters B, β and Dq. The B-values suggest a strong covalency in the metal-ligand σ-bond and t...

Copper(II) polymer complexes of empirical formula [Cu(ligand)2X2] (where X = Cl, Br, I, NO3, and $$\frac{1}{2}$$ SO4) and [Cu(ligand)(CH3COO)2] have been prepared with poly(3-phenylacrylidine semicarbazone). All the polymer complexes prepared have been characterized by elemental analysis, magnetic moment, conductance, IR, electronic, 1H-NMR, and electronic paramagnetic resonance spectral studies. The polymer complexes [Cu(ligand)2X2] and [Cu(ligand) (CH3COO)2] may have tetragonal symmetry while the [Cu(ligand)2( $$\frac{1}{2}$$ SO4)2] may be five-coordinate trigonal bipyramidal in structure. All complexes exhibit normal magnetic moments corresponding to one unpaired electron except [Cu(ligand)(CH3COO)2] which shows a subnormal magnetic moment. EPR spectra of the polymer complexes have been studied with a view to assigning their stereochemistries. Various EPR parameters have been calculated. The g, A, G values for all the polymer complexes are consistent with a tetragonal 1–5 and trigonal bipyramidal 6 stereochemistry in the Cu(II) polymer complexes of homopolymer.

The kinetics of the oxidation of the 2-aminomethylpyridineCoII complex by N-bromosuccinimide (NBS), have been studied in aqueous solutions under various conditions, and obey the following rate law