| Hydrazones are azomethines characterized by the grouping C N N . They are distinguished from other members of this class (imines, oximes,……etc). Hydrazones in general are prepared by refluxing the stoichiometric amounts of the appropriate hydrazine and aldehyde or ketone dissolved in a suitable solvent. The compound usually crystallize out on cooling.In this thesis we report the synthesis of a home-made ligand (2-pyridinearboxaldehyde isonicotiny ydrazone) and a new ligand (Pyrrolyl-2-carboxaldehyde isonicotinoylhydrazone) and its Copper (II) and Cobalt (II) complex.1. Synthesis of a home-made ligand 2-pyridinearboxaldehyde isonicotiny hydrazone(2-PYAINH)Equimolar solutions of 2-pyridinecarboxaldehyde and isonicotinoylhydrazine in anhydrous ethanol were refluxed for 2 h, then the contents were cooled to room temperature; the white precipitate was separated by filtration, washed with hot ethanol and dried in vacuum.2. Synthesis of a new ligand pyrrolyl-2-carboxaldehyde isonicotinoylhydrazone(PY-2-AINH)Equimolar solutions of pyrrolyl-2-carboxaldehyde and isonicotinoylhydrazine in anhydrous ethanol were refluxed for 2 h, then the contents were cooled to room temperature; the white precipitate was separated by filtration, washed with hot ethanol and dried in vacuum. Recrystallized from hot aqueous methanol (m. p. 180-182°C, 74 % yield, and color is white). The band at 1666 cm-1 is due to the C=O group and absorption bands at 1552 cm-1 due to the C=N group of the reagent, from these absorption bands and elemental analyses of the reagent, one can conclude that the newly synthesized compound is a novel reagent. 3. Synthesis of complexes of pyrrolyl-2-carboxaldehyde isonicotinoylhydrazoneThe complexes were prepared by adding metal acetate (0.5 mo1) [metal = Co (II), and Cu (II)] in ethanol (10 ml) dropwise to the hot solution of ligand in ethanol (10 ml). The mixture was maintained under reflux for 3 h, then cooled, filtered, washed with ethanol and dried in vacuum. While preparing the cobalt complex, a drop of glacial acetic acid was added to the cobalt acetate solution to prevent its hydrolysis. The purity of complexes was checked by TLC and elemental analyses.Hydrazones are a versatile class of compounds with several applications. Due to their chelating behavior, hydrazones are used in analytical chemistry as selective metal extracting agents as well as in spectroscopic determination of certain transition metals. Hydrazone derivatives are found to possess antimicrobial, anti-tubercular, anti-convulsant and anti-inflammatory activities.In analytical chemistry, hydrazones find application by acting as multidentate ligands with metals (usually from the transition group). Various studies have also shown that the azomethine group having a lone pair of electrons in either a p or sp2 hybridized orbital on trigonally hybridized nitrogen has considerable biological importance.Hydrazones found a wide analytical application. They are extensively used in the detection, determination and isolation of the compounds containing carbonyl group. Hydrazones and their coordination compounds are well known to be biologically important and interest for their antibacterial, antitumour and antitubercular activities. Structural and spectral investigations on copper (II) complexes continue to be interesting because of the stereochemical versatility offered by copper(II). ESR spectroscopy has emerged as another powerful method for elucidating the solid state structure and bonding as well as for understanding the solution dynamics of copper(II) complexes. It also detects variations in coordination geometry due to ligand substituents as well as multiple valencies of the same metal. Moreover, the copper(II) complex of salicylaldehyde benzoylhydrazone was shown to be a potent inhibitor of DNA synthesis and cell growth. Some hydrazone analogues have been investigated as potential oral iron chelating drugs for the treatment of genetic disorders such as thalassemia and have also been suggested as possible metal chelating agents for treating neurodegenerative disorders such as Alzheimer disease. Novel iron chelating agents belonging to the group of aromatic hydrazones are currently investigated as potential drugs for the treatment of various human pathologies, including iron overload-associated diseases, cancer, anthracycline-induced cardiotoxicity and tuberculosis. Salicylaldehyde isonicotinoyl hydrazone (SIH) is among the most promising agents of this group. Besides its ability to reduce cellular-iron burden in iron-overload models, it has been also shown to possess significant cardioprotective activity against oxidative stress-induced injuryThe aim of this thesis is concerned with the analytical application of the hydrazone 2-pyridinearboxaldehyde isonicotiny hydrazone as a reagent for the spectrophotometric determination of several ions such as (Nickel(II), Copper(II), Cobalt(II) and Iron(III)). The basis of spectophotometric methods is the simple relationship between interaction of a beam of radiation and matter.Several factors includes wavelength, standing time and pH have been studies, the study also includes the determination of the stoichiometric of 2-pyridinearboxaldehyde isonicotiny hydrazonewith metal ions by molar-ratio method.The linearity range of Beer's law for the determination of metal ion was examined. The effect of the foreign ions on the determination of the interested metal ions has been investigated.The results showed that the reagent 2-pyridinearboxaldehyde isonicotiny hydrazone provides a simple, sensitive, selective and direct method for the spectophotometric determination of (nickel(II), copper(II), cobalt(II) and iron(III)) in the aqueous solution. This method gives it's maximum absorption values at wavelengths of 363, 352, 346 and 359 nm, respectively. Also, preferable pH values for the complexation of these metal ions were 7.0, 9.0, 8.0 and 8.0, respectively.The results also showed that the stoichiometry of metal-ligand complexes were 1:2 for Ni-2-PYAINH, 1:2 for Cu-2-PYAINH, 1:2 for Co-2-pyridinearboxaldehyde isonicotiny hydrazoneand and 1:1 for Fe-2-PYAINH.This method obeys Beer's law in the range of 0.01-1.4, 0.01-1.5, 0.01-2.7 and 0.005-5.4 mg/L for nickel (II), copper (II), cobalt (II) and iron (III), respectively.The results show that, the simple linear-regression calibration equations for nickel (II), copper (II), cobalt (II) and iron (III), A=0.76C+0.069, A=0.38C+0.11, A=0.27C+0.26 and A=0.069C+0.17, with correlation coefficient of 0.9999 (n=6), 0.9996 (n=10), 0.9995 (n=13) and 0.9992 (n=5), respectively.The results also show that, Sandell's sensitivities and relative standard deviations were 8.4x104, 5.2x104, 7.1x104 and 3.9x104 L mol-1 cm-1, 0.00069, 0.0012, 0.00078 and 0.0014μg cm-2, and 1.010%, 2.023%, 1.715% and 1.813%, for nickel (II), copper (II), cobalt (II) and iron (III), respectively.The results show that, the detection limits were found to be 0.001, 0.002, 0.003 and 0.01 mg/L, for nickel (II), copper (II), cobalt (II) and Iron (III), respectively.This thesis describes the preparation of the new ligand (pyrrolyl-2 carboxaldehyde isonicotinoylhydrazone), obtained in the reaction of pyrrolyl-2-carboxaldehyde with isonicotinoylhydrazine, and its copper (II) and cobalt (II) complex. These copper (II) and cobalt (II) complexes are characterized by elemental analyses, magnetic and conductance measurements, spectroscopic methods, ESR, IR, 1H NMR, thermal studies and electronic spectral studies.1. The analytical data and physical properties of P-2-AINH and of cobalt (II) and copper (II) complexes. the results from analytical data and physical properties of the ligands and coordination compounds show that the ligand coordinates to the metal ion in a 2:1 molar ratio. The ligands are soluble in hot ethanol and strong polar solvents such as in DMF and DMSO. All compounds are stable in air. The melting points of the complexes are higher than that of the ligands revealing that the complexes are much more stable than the ligands. Due to insolubility of the complexes in benzene/nitrobenzene the molar conductance values of the complexes was shown to be in the range 21.70–22.2 --1 cm2 mol-1 (at 25 -C) which indicates that the complexes are of non-electrolytic nature.2. Infrared spectra of ligand and cobalt (II) and copper (II) complexThe IR spectra of the ligand and cobalt (II) and copper (II) complex show characteristic absorption bands at 3178, 1666, 1552, 1470 and 957 cm-1 due toν(N-H),ν(C=O),ν(C=N),δ(N-H) andν(N-N), respectively. The IR spectra of the ligand, Co(II) complex and Cu(II) complex, respectively, reveal significant changes compared to the ligand. The absorption bands attributed toν(N-H),ν(C=O) andδ(N-H) disappeared in the complexes and two new bands due to conjugate systemν(>C=N-N=C<) andν(C-O) appeared in the regions 1638–1641 and 1338–1359 cm-1, respectively. The band forν(C=N) undergoes a bathochromic shift of 30–33 cm-1 (in HL) andν(N?N) band exhibited a hypsochronic shift of 37–43 cm?1 (in HL) which indicate that the metal ions form neutral coordination compounds with the ligand in the enol form through the azomethine nitrogen and amide oxygen negative ion . A shift ofν(C=N) band to a lower frequency is due to the conjugation of the p-orbital on the double bond with the d-orbital on metal ion with reduction of the force constant. A shift ofν(N?N) band to a higher frequency is attributed to the electron attracting inductive effect when forming the conjugated system. In the far-IR region two new bands around 543–557 and 425–438 cm?1 in the complexes can be assigned toν(M? O) andν(M? N), respectively.3. 1H NMR spectraThe NMR spectrum of the ligands exhibits─NH (2-pyrrole) proton at 12.46 ppm,─NH (hydrazid) proton at 11.76 ppm, 2-pyrrole ring protons at 6.15–7.12 ppm (multiplets), 2-pyridine ring protons at 7.44–8.75 ppm (multiplets) and etheonyl protons at 7.94 and 8.79 ppm (each as a doublet). The 1H NMR spectra of the complexes cannot be obtained due to interference in their paramagnetic properties.4- Electronic spectral studiesThe ligand field spectra of all the complexes were recorded in DMF at room temperature. The electronic spectrum of the ligand in DMF showed the n→π* andπ→π* transitions as a band with a shoulder at 315 and 295 nm, respectively. The electronic spectral data of the complexes in DMF are in good agreement with their geometries. The UV absorption bands exhibit a charge transfer transition (CT) in the range 385 to 410 nm for Co(II) and Cu(II) complexes and may be assigned to the ligand-to-metal charge transfer transition.5- Magnetic studiesThe cobalt(II) complex was found to be paramagnetic which excludes the possibility of square planar configuration. The measured magnetic moment value for cobalt(II) complex of 3.37 BM is an evidence for tetrahedral geometry. The magnetic moment value of the copper(II) complex under study, 1.79 BM, is an evidence for square planar geometry.6- Electron spin resonance spectroscopy (ESR)The powder ESR parameters of the copper(II) complex measured at room temperature. The low g-value of copper(II) complex, indicating more covalent planar bonding and two ligands are likely bidentate, N, O, donor. From the observed g-values, it is clear that the unpaired electron lies predominantly in the dx2–y2 and implying a 2B1g as a ground state. The g-value for copper(II) complexes is greater than 2 indicating to the presence of Cu─O and Cu─N bonds as Kivelson and Neiman have suggested that the g11 value in the Cu(II) complex can be used as a measure of covalent character of the metal–ligand bond. For the ionic environment, the gII value is normally 2.3 or higher and for the covalent environment, it is less than 2.3. Using this criterion, the data show considerable covalent character of the metal–ligand bonding of the present complex.7. Thermal analysisTG and DTA studies were carried out on the ligand and its complexes in the temperature range of 20–850 ?C. The thermal analyses show that there are three endothermic peaks and only one exothermic peak in the range of 400-460 ?C in the DTA curve of the ligand. The first appeared at 172 ?C is melting point of the ligand, because no loss of weight was observed in the TG curve. The second and third peaks appeared above 250 ?C where the weight loss on the corresponding TG curve indicates decomposition of the ligand. The decomposition is complete at about 390 ?C where an exothermic peak arises from the pyrolysis of the organic residues. The thermal decomposition curves of the complexes are different from that of the ligand. There is no endothermic peak, only a series of exothermic ones in the DTA curves indicating no melting points for these complexes .The first step of decomposition of the Cu(II) complex is at 280–320 ?C. The second step of decomposition of the Cu(II) complex starts from about 370 ?C and continues up to 500 ?C. The first step of decomposition of the Co(II) complex is at 320–360 ?C. The second step of decomposition of the Co(II) complex starts from about 390 ?C and continues up to 470 ?C . There are three stages of weight loss of Co(II) complex seen from the TG curve: (1) from 300 to 320 ?C, 30% weight loss and (2) from 320 to 420 ?C, about 65% weight loss due to the pyrolysis of organic compounds; (3) 5% weight loss from 420 to 470 ?C arising from the pyrolysis of the organic residues. There are also three stages of weight loss of Cu (II) complex seen from the TG curve: (1) from 240 to 270 ?C, 55% weight loss (2) from 270 to380 ?C, about 30% weight loss due to the pyrolysis of organic compounds; (3) 15% weight loss from 380 to 440 ?C arising from the pyrolysis of the organic residues. This thesis describes the analysis of real samples. In order to test the applicability of the proposed method, it has been applied for determination of cobalt, copper, nickel and iron in real samples. For this we analysed two mineral and one tap water samples. To each sample was added 1 mg/L of metal ions. In all the samples, extremely good recoveries have been obtained.Through the studying of this method, it was noticed that:1. Selective and sensitive reagent of 2-pyridinecarboxaldehyde isonicotinylhydrazone (2-PYAINH) was for the first time synthesized and studied for the spectrophotometric determination of trace amounts of nickel, copper, cobalt and iron in detail.2. Proposed method is one of the most selective, sensitive, economy and rapid methods for spectrophotometric determination of trace amounts of nickel, copper, cobalt and iron in the aqueous solution3. Proposed method does not require any extraction or pre-concentration step.4. The methods were applied successfully for the analysis of metal ions in two mineral and one tap water samples.5. The limits of detection herein reported are extremely challenging, if compared with similar methods.6. The good agreement clearly demonstrates the utility of this procedure for the determination of iron, cobalt, nickel and copper without tedious pretreatment in complex samples such as biological materials.7. The structural characterizations of synthesized complexes were made by using the elemental analysis, spectroscopic methods, magnetic and conductance measurements, thermal studies. From the spectroscopic characterization, it is concluded that Pyrrolyl- 2-carboxaldehyde isonicotinoylhydrazone(PY-2-AINH) acts as a bidentate ligands, coordinating through carbonyl oxygen and azomethine nitrogen.8. Because of the stable complex of Cu(II) and Co(II) (PY-2-AINH) made to study in environmental samples may be extended to the routine analysis of pharmaceutical samples of bulk and formulations.
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