Estimation of iron with salicylaldehyde hydrazone

Iron is determined by precipitation as the reddish orange ferrous complex of salicylaldehyde hydrazone (SH) in the pH range 10.0-11.0. With ferric iron an unstable complex is formed which changes readily to the stable ferrous complex. The iron complex has a metal-ligand ratio of 1:2, contradicting the 1:3 ratio reported earlier. The reagent can be used for separation of iron from several ions.     

Reactions of group 6 metal carbonyls with salicylaldehyde isonicotinic acid hydrazone

Sunlight irradiation of the reactions of [M(CO)₆], M?=?Cr, Mo and W with salicylaldehyde isonicotinic acid hydrazone (H₂salnah) in THF were investigated. Interaction of [Cr(CO)₆] with H₂salnah resulted in formation [Cr₂O₂(H₂salnah)₂]. The corresponding reactions of molybdenum and tungsten carbonyls yielded dinuclear oxo complexes [M₂O₆(H₂salnah)]. All complexes were characterized by elemental analysis, IR, mass spectrometry and ¹H NMR spectroscopy. The IR spectra of complexes exhibited bands due to either terminal or bridged metal oxygen bonds. Magnetic measurement of [Cr₂O₂(H₂salnah)₂] showed it has paramagnetic characteristics with high spin d⁴ configuration and μ_eff of 1.27?BM. Electronic spectra of the complexes in DMF displayed visible bands due to ligand-to-metal charge transfer. Thermal properties of the complexes were investigated by thermogravimetry technique.     

Infrared study of complexes between iron,salicylaldehyde benzoyl hydrazone and seven analogous derivatives

Summary An i.r. study of Fe complexes prepared from salicylaldehyde benzoyl hydrazone and seven similar chelating agents allowed the assignment of some iron-ligand bands. The amide I and —O band shifts indicate that the ligand O atoms are directly linked to Fe. The analogy between Fe^II and Fe^III complexes in the mid-i.r. range and the chiefly identical frequencies in the far-i.r. range provide evidence that oxidation of Fe^IIhas occurred. The bands directly involved in complexation are shifted compared to the free hydrazones, and all are medium or weak.     

Fluorimetric determination of gallium in a nickel alloy and aluminium with N-oxalylamine(salicylaldehyde hydrazone)

A fluorimetric determination of gallium, based on the formation of the fluorescent chelate with N-oxalylamine(salicylaldehyde hydrazone) (OSH)-Ga(III), is proposed. The complex has excitation and emission maxima at 395 and 475 nm, respectively. The detection limit is 3 ng/ml and Ga can be determined up to 277 ng/ml. The method has been applied to the determination of gallium in a nickel alloy and aluminium. Extraction with n-butyl acetate from 6M hydrochloric acid medium has been used to separate Ga from the interfering elements in the alloys.     

Analgesic and anti-inflammatory activities of salicylaldehyde 2-chlorobenzoyl hydrazone (H(2)LASSBio-466), salicylaldehyde 4-chlorobenzoyl hydrazone (H(2)LASSBio-1064) and their zinc(II) complexes

Salicylaldehyde 2-chlorobenzoyl hydrazone (H(2)LASSBio-466), salicylaldehyde 4-chlorobenzoyl hydrazone (H(2)LASSBio-1064) and their complexes [Zn(LASSBio-466)H(2)O](2) (1) and [Zn(HLASSBio-1064)Cl](2) (2) were evaluated in animal models of peripheral and central nociception, and acute inflammation. All studied compounds significantly inhibited acetic acid-induced writhing response. Upon coordination the anti-nociceptive activity was favored in the complex 1. H(2)LASSBio-466 inhibited only the first phase of the formalin test, while 1 was active in the second phase, like indomethacin, indicating its ability to inhibit nociception associated with the inflammatory response. Hence coordination to zinc(II) altered the pharmacological profile of H(2)LASSBio-466. H(2)LASSBio-1064 inhibited both phases but this effect was not improved by coordination. The studied compounds did not increase the latency of response in the hot plate model, indicating their lack of central anti-nociceptive activity. All compounds showed levels of inhibition of zymosan-induced peritonitis comparable or superior to indomethacin, indicating an expressive anti-inflammatory profile.     

Recent analytical developments using chemiluminescence in solution

The rapid growth of analytical methods which utilize chemiluminescent techniques reflects their many advantages relative to conventional procedures. Measurement of light emission is simple and rapid and extremely high sensitivities may be achieved with inexpensive instrumentation and without resort to preconcentration. As a consequence, attention is now being directed towards expanding the scope of chemiluminescent analyses, both by study of previously unexploited fight-emitting processes and by modification to determine specific analytes of interest. This review describes the requirements and methodology, presents newer applications of established procedures and considers the potential of some new systems for chemiluminescent analysis.     

Influence of structural factors on the magnetic properties of the binuclear copper complexes with salicylaldehyde hydrazone and bis(hydrazone)-2,6-diformylphenol: Quantum-chemical calculations

The structures and magnetic properties of the binuclear copper complexes of salicylaldehyde mono- and bis(hydrazone) derivatives were studied by the quantum-chemical density functional theory (B3LYP/6-311⁺⁺g(d,p)) using the broken-symmetry technique. The change in the degree of deprotonation of the ligands was found to exert an insignificant effect on the magnetic properties, whereas the coordination of solvent molecules substantially weakened the antiferromagnetic interaction.     

Determination of quinones by a chemiluminescence reaction in solution

Oxidation of p-benzoquinone by hydrogen peroxide in an alkaline medium gives chemiluminescence emission with maximum intensity at 660 and 560 nm. 1,4-Naphthaquinone gives only a single maximum at 660 nm. These emissions can be used for the determination of microg amounts of the quinones. The interference effect of some organic compounds is described.     

Determination of aliphatic aldehydes in aqueous solution by chemiluminescence measurements

The determination of aliphatic aldehydes (5 × 10^-6 — 2.5 × 10^-4 mol) in aqueous solution was achieved by inhibition of the luminol chemiluminescence induced by hydrogen peroxide in the presence of potassium hexacyanoferrate(III).     

Development of high-performance liquid chromatographic determination of salicylaldehyde isonicotinoyl hydrazone in rabbit plasma and application of this method to an in vivo study

An analytical methodology appropriate for the determination of the novel drug candidate salicylaldehyde isonicotinoyl hydrazone (SIH) in rabbit plasma has been developed and validated. Desirable chromatographic separation was achieved on a C18 column employing a mixture of phosphate buffer (0.01 M NaH2PO4 x 2 H2O with 2 mM EDTA, pH 6.0) and methanol (53:47; v/v) as the mobile phase. In order to develop a suitable sample preparation procedure, different methods have been tested (solid-phase extraction, liquid-liquid extraction, and protein precipitation). Protein precipitation using 0.1 M HClO4 and acetonitrile allowed the highest recoveries of the analyte to be reproducibly attained. The analytical methodology developed in this study was validated with respect to linearity (0.26-30.0 microg/mL), accuracy, precision, selectivity, recovery, and stability. A concentration of 0.26 microg/mL was determined as the LLOQ. The chromatographic method was applied to a preliminary plasma pharmacokinetic study. This study has provided the first information about the concentrations of SIH in plasma of a living subject. These results could have a significant impact on further progress in the development of this promising compound.     

Synthesis,structural characterization,in vitro cytotoxicities,and BSA interaction of di-organotin(IV) complexes derived from salicylaldehyde nicotinoyl hydrazone

Two organotin(IV) compounds were synthesized from salicylaldehyde nicotinoyl hydrazone and the corresponding dialkyltin(IV) precursor. Their structures were determined by IR, elemental analysis, NMR, and single crystal X-ray diffraction analysis. Compound 1 exhibits a distorted trigonal bipyramidal geometry around tin, which is coordinated to the Schiff-base ligand in an enolic tridentate fashion. For 2, structural analysis reveals that it is a centro-symmetric trimer, in which the central Sn adopts a six-coordinate octahedral geometry and the other two Sn ions adopt five-coordinate trigonal bipyramidal geometry. In vitro cytotoxicities of the compounds against three human cisplatin-resistant tumor cell lines (A549, HeLa, and MCF-7) were assessed by MTT assay. Further, the interaction of 1 and 2 with bovine serum albumin (BSA) has been explored by the titration method with fluorescence quenching spectra and synchronous ?uorescence spectra. Studies reveal that di-n-butyltin(IV) complex 1 with significant antiproliferative effects in the cells shows stronger BSA interaction.     

Photoinduced oxygen uptake of diphenylamines in solution and their ring closure revisited

The photochemistry of diphenylamine (DPA), N-methyldiphenylamine (MeDPA), and triphenylamine (TPA) was studied in solution at room temperature. The major photoprocess was cyclization, and the quantum yields were Phicyc = 0.02-0.6. The photoinduced oxygen uptake/consumption, studied in air-saturated acetonitrile-water or methanol-water, was efficient. Three subsequent transients, the polyphenylamine triplet state, the 4a,4b-dihydrocarbazole triplet state, and its labile ground state, were accessible by laser flash photolysis prior to carbazole formation. Their yields were determined and compared with the Phicyc values. Oxygen can reduce or enhance Phicyc since one step, quenching of the polyphenylamine triplet state, blocks cyclization and one step, scavenging of dihydrocarbazole, favors cyclization since it competes successfully with the back-reaction to the substrate. The former is dominant for DPA in solvents with low and high polarity and the latter is dominant for MeDPA preferentially in nonpolar solvents as well as for TPA in all solvents.     

Determination of polynuclear aromatic hydrocarbons in micellar solution by electrogenerated chemiluminescence

When polarized cathodically in aqueous acetate solution (pH 7.0) containing peroxodisulfate, a micelle-forming surfactant (Brij-35) and a polynuclear aromatic hydrocarbon, an oxide-covered aluminum electrode produces an intense electroluminescence where the emitting species is the micelle-encapsulated hydrocarbon. The detection limit is ca. 10^?8 M for 9,10- diphenylanthracene.     

Photoinduced isomerization kinetics of diiodomethane in supercritical fluid solution: local density effects

The density dependence of diiodomethane photoinduced isomerization in supercritical (sc) CO2, CHF3, and C2H6 was investigated by transient absorption spectroscopy, covering a fluid density range from 0.7 to 2.5 (in reduced units). The solvent-caged photoproduct iso-diiodomethane is formed even at the lowest density, and its yield increases about 4-fold over the whole range. At the same time, isomer formation rate constants increase by roughly an order of magnitude and show little variation between CO2, C2H6, and CHF3. Furthermore, the formation rate constant decreases significantly with increasing excitation energy. We propose an isomer formation mechanism involving a rapidly established preequilibrium between a solvent-caged iodine atom-methyliodide radical pair and a loosely bound iodine-methyliodide radical complex, from which the reaction subsequently proceeds to the isomer. The latter step seems to be controlled by collisional stabilization of the initially hot radical moiety, as the formation rate constant increases linearly with sc solvent viscosity. The model predicts a quadratic dependence of relative isomer yield on fluid density. A corresponding correlation is found with the local fluid density, calculated via solute-solvent radial distribution functions obtained from molecular dynamics (MD) simulations.     

Near-ultraviolet chemiluminescence from the reaction of ammonia with hypobromite in aqueous solution

The chemiluminescence arising from the oxidation of ammonium chloride by sodium hypobromite in aqueous alkaline solution includes a series of peaks in the near-ultraviolet, which is not commonly observed in liquid-phase chemiluminescence. The dominant peak in that region has an intensity maximum at 292 nm and smaller peaks are observed at 313, 334 and 356 nm. The emitted photons are of similar energy to the Vergard-Kaplan transition of molecular nitrogen, a major product of this reaction. However, the spectral distribution is different to that of previously reported gas-phase chemiluminescence attributed to the Vergard-Kaplan transition.     

Some aromatic hydrazone derivatives as inhibitors for the corrosion of C-steel in phosphoric acid solution

The effect of furfural benzoylhydrazone and its derivatives (I-VII) as corrosion inhibitors for C-steel in 1M phosphoric acid solution has been studied by weight-loss and galvanostatic polarization techniques. A significant decrease in the corrosion rate of C-steel was observed in the presence of the investigated inhibitors. This study revealed that, the inhibition efficiency increases with increasing the inhibitor concentration, and the addition of iodide ions enhances it to a considerable extent. The effect of temperature on the inhibition efficiency of these compounds was studied using weight-loss method. Activation energy (E(a)*) and other thermodynamic parameters for the corrosion process were calculated and discussed. The galvanostatic polarization data indicated that, the inhibitors were of mixed-type, but the cathode is more polarized than the anode. The adsorption of these compounds on C-steel surface has been found to obey Frumkin's adsorption isotherm. The mechanism of inhibition was discussed in the light of the chemical structure of the undertaken inhibitors.     

Orthogonal or simultaneous use of disulfide and hydrazone exchange in dynamic covalent chemistry in aqueous solution

Hydrazone and disulfide exchange have been combined in a single system, but can be addressed independently: by adjusting the pH of the solution from acidic to mildly basic it is possible to switch from exclusively hydrazone exchange to exclusively disulfide exchange, while at intermediate pH both reactions occur simultaneously.     

The mechanism of the electrogenerated chemiluminescence of luminol in aqueous alkaline solution

The mechanism of the electrogenerated chemiluminescence of luminol in aqueous alkaline solution based on the rotating ring—disc electrode system is discussed. The disc electrode is maintained at a negative potential and the ring electrode at a symmetrically changing double-step potential. Hydrogen peroxide generated at the disc electrode by the reduction of oxygen is immediately transported to the ring electrode because of electrode rotation. Hydrogen peroxide and luminol are oxidized at the ring electrode during the positive pulse of the double-step potential. These oxidation processes generate a superoxide radical and a luminol radical as intermediates. The luminol radical reacts with the superoxide radical (or oxygen) emitting light.     

Electrogenerated chemiluminescence from CdS nanotubes and its sensing application in aqueous solution

Electrogenerated chemiluminescence (ECL) of CdS nanotubes in aqueous solution and its sensing application were studied by entrapping the CdS nanotubes in carbon paste electrode. Two ECL peaks were observed at −0.9 V (ECL-1) and −1.2 V (ECL-2), respectively, when the potential was cycled between 0 and −1.6 V. The electrochemically reduced nanocrystal species of CdS nanotubes could collide with the oxidized species in an annihilation process to produce the peak of ECL-1. The electron-transfer reaction between the reduced CdS nanocrystal species and oxidant coreactants such as S₂O₈²⁻, H₂O₂, and reduced dissolved oxygen led to the appearance of the ECL-2 peak. Based on the enhancing effect of H₂O₂ on ECL-2 intensity, a novel CdS ECL sensor was developed for H₂O₂ detection. The sensor exhibited a detection limit of 0.1 μM and a linear range from 0.5 μM to 0.01 mM. The relative standard deviations of five replicate determinations of 5 μM H₂O₂ was 2.6%. In addition, the ECL spectrum in aqueous solution also exhibited two peaks at 500 and 640 nm, respectively.