Investigation of Substitution Reactions Between Zinc(II) Complexes with Different Geometries and N-bonding Nucleophiles

Aims: Investigation of interactions between zinc(II) complexes with different geometrical structures and relevant nitrogen donor nucleophiles at physiological pH. Background: The lack of clear distinction between the therapeutic and toxic doses of platinum drugs is a major challenge for the design of novel non-platinum DNA and protein targeting metal-based anticancer agents. The non-platinum antitumor complexes could be alternatives to platinum-based drugs due to their better characteristics and different mechanism of action. Objective This study could provide more information for the design of future zinc-based anticancer drugs, as well as providing a better understanding of the mechanism of interactions between Zn(II) complexes and nitrogen-donor nucleophiles (important from a medical point of view) and clarifies the changes in geometrical structures of zinc(II) that are referred to structure-reactivity correlation Methods Mole-ratio method and UV-Vis spectroscopic kinetic method were applied in this study. Objective : This study could provide more information for the design of future zinc-based anticancer drugs, as well as providing a better understanding of the mechanism of interactions between Zn(II) complexes and nitrogen-donor nucleophiles (important from a medical point of view) and clarifies the changes in geometrical structures of zinc(II) that are referred to structure-reactivity correlation Methods Mole-ratio method and UV-Vis spectroscopic kinetic method were applied in this study. Result: The results indicated additional coordination of chlorides in the first coordination sphere with changes in coordination geometry and formation of the octahedral complex anion [ZnCl4(en)]2- while an excess of chloride didn’t affect the square-pyramidal structure of [ZnCl2(terpy)]. The substitutions of studied complexes and relevant nucleophiles proceed in two consecutive reaction steps that depend on the nucleophile concentration. Octahedral complex anion [ZnCl4(en)]2- forms rapidly, and all substitution processes of this complex species should be considered. We assume that the first reaction step is accompanied by the dissociation of chloride ligands. Nucleophile 1,2,4-triazole have shown the highest affinity toward [ZnCl2(en)], and rates of both steps are almost the same value, which indicates parallel reactions. Conclusion: The different order of reactivity of relevant N-donor ligands toward [ZnCl2(en)] and [ZnCl2(terpy)] complexes for the first reaction step occurred due to the influence of different geometrical structures of complexes. In contrast, low reaction rates for the second reactions of [ZnCl2(en)] complex with imidazole and pyrazine were a consequence of interconversion between octahedral and tetrahedral structure during substitution processes.

Determination of Stability Constants and Thermodynamic parameters of Cefotaxime –Fe(III) Complex at Different Temperatures

Cefotaxime, a β-lactam antibiotic, has a structure which enables it to act as a chelating agent. The formation of Fe(III) complex with cefotaxime has been studied colorimetrically at an absorption maximum of 480 nm at different temperatures. The data showed that Fe(III) and cefotaxime combine in the molar ratio of 1:1 at pH 7.4 with ionic strength maintained using 0.1M KNO3. The stability constants of the complex were calculated to be 1.56 - 1.90 x 104 by continuous variation method and 1.34 - 1.71 x 104 by mole ratio method at 25 and 40 oC respectively. ∆HƟ values for the complex were calculated to be -1.02 x 104 and -1.05 x 104 J by continuous variation method and mole ratio method respectively. ∆GƟ of the complex were calculated to be -2.44 – (-2.51) x 104 J by continuous variation method and -2.41- (- 2.48) x 104 J by mole ratio method at 25 and 40 oC. ∆SƟ of the complex were calculated to be 2.44 - 2.51 x 104 J/K by continuous variation method and -2.41 -2.48) x 104 J/K by mole ratio method at 25 and 40 oC respectively. Cefotaxime is a good chelating agent and can be an efficient antidote in the therapy of copper overload or poisoning.

SYNTHESIS OF SPINEL Mn3O4 AND SPINEL Mn3O4/ZrO2 NANOCOMPOSITES AND USING THEM IN PHOTO-CATALYTIC DECOLORIZATION OF Fe(II)-( 4,5- DIAZAFLUOREN-9-ONE 11) COMPLEX

The spinel structure Mn3O4 and the spinel Mn3O4/ZrO2 nano-composites particles were synthesized successfully as photocatalysts by employing the co-precipitation process and ultrasonic technique, respectively. The morphology of the top mention prepared photocatalysts was distinguished using X-ray diffraction (XRD) technology and atomic force microscopy (AFM) and indicated that the mean crystal sizes and particle sizes for all studied samples were nanometric. In addition, the optical properties of the obtained photocatalysts were investigated using a UV-Visible spectrophotometer with Labsphere diffuse reflectance accessory to measure the bandgaps of them. Based on the Tauc equation, the bandgaps (Bg) for the studied photocatalysts were determined. The bandgaps are indirect for all samples, and it is increased in values for the nanocomposites with the increasing the ratio of ZrO2. So, the sequence of bandgaps values is: Bg spinel Mn3O4 Bg Comp.1 Bg Comp.2 Bg Comp.3 Bg ZrO2, and equal to 2.21 eV 3.15 eV 4.51 eV 4.26 eV 5.29 eV. The research revealed that the spinel Mn3O4 and the spinel Mn3O4 ZrO2 nano-composites particles were quasispherical and spherical particles respectively. Moreover, the incorporation of spinel Mn3O4 particle with ZrO2 particle was successfully carried out that was proved by XRD and AFM analyses. This work discovered that the photocatalytic reaction response via employing Fe(II)-(4,5-Diazafluoren-9-one 11) complex as model material under UV-A lamp with the use of the studied photocatalysts. The primary photo experiments for these photocatalysts found that the decolorization of Fe(II)-(4,5-Diazafluoren-9-one 11) complex is not active without addition of H2O2, that attitude is due to the very high stability of these complex with having an octahedral structure, which was proved with using mole ratio method. Whereas, after the addition of H2O2 to the aqueous solution of these complex, the activity with using the spinel Mn3O4 ZrO2 nanocomposite 3 was found to be the double active than that using the spinel Mn3O4 alone, and the sequence of phootdecolorization efficiency (E%) is being: E% composite 3 E% composite 2 E% composite 1 E% spinel Mn3O4.

Synthesis, Identification of Co(II), Cu(II) and Ni(II) Complexes with A Schiff Base–Azo Ligand Derived from Imidazol Derivatives, 4- Aminoacetophenon and 4- Chloroaniline and Study Their Physical Properties and Their Thermodynamic Stabilities

The complexes of Co(II), Cu(II) and Ni(II) were synthesized by using schiff base – azo as a ligand, which were prepared under this study by the reaction between the Schiff base diazonium salt and the imidazole derevitive. They were characterized by element analysis, FTIR spectroscopy and UV.VIS. spectroscopy. Their electric conductivity and magnetic features were determined. Their stepwise and overall stability constants and their thermodynamic data ( , and ) were determined. The results showed that all the complexes have paramagnetic features and all of them have good conductivity. The formula of the complexes under this paper were suggested by using the mole ratio method which lead to the formation of (1 : 2) metal : ligand formula for all the complexes. In all the complexes the coordinated sites was through N atoms of the azo groups and N atom of the imidazol ring. The suggested geometrical shapes of the complexes was the octahedral shape due to the ( d2sp3 ) hybridization. Their stepwise stability constants were determined, it was found that for all the complexes they were increased toward the addition of ligand that because of the chelate effect. Their overall stability constants were determined, it was found that for all the complexes were high that because of the chelate effect. Their thermodynamic functions ( , and ) were had negative value, that refer to good stability for the complexes and these results were satisfied with the spontaneous reaction and high stability complexes.

Preconcentration and Spectrophotometric Determination of Copper and Nickel in some Medicinal PlantsafterCloud Point Extraction

In this work,Cloud point extraction (CPE) methodology as an one green chemistry method is used for extraction, enrichment and determination ofNi (II) and Cu (II) in the somemedicinal plants,by use organic reagent2-[ (6-Methyl-2-Benzothiazolyl)azo]-4-Chloro Phenol (6-MeBTAClP) for formationthe extracted complexes into micelles of Triton X-114 as a mediated extractant at65,70 C0 respectively. The extracted product in densityhigh (cloud point layer )is separated from the aqueous layer by centrifugation for 15 min and dissolved in 0.5 mLfrom ethanol followed the determination of Ni (II) and Cu (II)by using spectrophotometry at a wavelength maximum of 644 and 598 nm respectively. The optimum conditions established as pH, The linear range of Ni (II) and Cu (II)along with limit of detection,precision expressed as relative standard deviation for seven replication measurements and the recovery range were obtained for Ni (II) and Cu (II) ions,respectively. The complex s identified by UV-Visible and IR spectra. The mole ratio method and continuous variation method (Job’s method)also investigated.

DEVELOPMENT OF EXTRACTIVE SPECTROPHOTOMETRIC METHOD FOR THE DETERMINATION OF IRON (III) WITH SCHIFF BASE 2-[(2-HYDROXYPHENYLIMINO) METHYL]-4-NITROPHENOL

Objective: A simple spectrophotometric method has been developed for the determination of Iron (III) by using Schiff base 2-[(2-hydroxyphenylimino) methyl]-4-nitrophenol [HPIMNP].Methods: HPIMNP extracts Fe (III) quantitatively (99.95%) into chloroform from an aqueous solution of pH range 4.0-6.0.Results: The chloroform extracts show maximum absorption at 510 nm (λ max). Beer’s Law is obeyed over the Fe (III) concentration range of 0.5 to 20.0 µg/ml. The Molar absorptivity and Sandell’s sensitivity for Fe–HPIMNP system is 5000 L mol ˉ1 cmˉ1 and 0.011 µg cmˉ2respectively. The composition of extracted species is found to be 1: 3 [Fe-HPIMNP] by Job’s continuous variation and Mole-ratio method. Interference by various ions has been studied.Conclusion: The proposed method is rapid, sensitive, reproducible and accurate and it has been satisfactory applied for the determination of Iron in Pharmaceutical Samples.