دراسات كيمياء الكم لمركبات الروثينيوم العضوية الفلزية == Quantum Chemical Studies of Ruthenium Organometallic Compounds
Author name:
دريد توفيق عريبي الكنبي
Supervisor name:
محسن عبود محسن العبادي | حسين جاسم محمد
General topic:
Chemistry
Specific topic:
Chemistry
Degree:
Doctorate
University:
University of Kufa - College Of Science - Chemistry Department
Language:
English
University location:
Najaf
First pages:
25T1433 - p.pdf
Abstract:
There are a wide variety of polyphenolic compounds named flavonids. These are extensively distributed in plants, and they are considered to be dietary antioxidants. They occur naturally in broad range of vegetables, fruits, and primarily recognized as the pigments.Many flavonoids have a metallic ion complexation capacity. The study of this capacity is important because it can be used in producing nutritional supplements, medicine, and heavy metal detoxification.Chelation therapy is the use of chelating agents (complexing agents) to detoxify poisonous metal such as mercury, arsenic, and lead by converting them to chemically inert form that can be excreted without further interaction with the body.Lead is considered as one of the most hazards and cumulative environmental pollutants that affect all biological system through exposure from air, water and food sources. It is toxic heavy metals which are known to induce a broad range of physiological, biochemical and behavioral dysfunction in humans. Because of its perverseness in the environment, lead poisoning still remains an important health problem.The polarographic measurements were carried out using differential pulse polarography (DPP), at hanging mercury drop electrode (HMDE) at the optimal conditions for flavonoids which were 1M HCl for Quercetin, Rutin, and Hespertin and 0.01M NaOH for chrysin as a supporting electrolyte.A well - defined two electron reversible reduction and diffusion controlled one wave for these flavonoide were observed, a linear relationship between concentration and diffusion current (id) was obtained with the value of correlation coefficient (r2) near to one, this obey Ilkovic equation. The values of n; the number of electrons transferred in the reduction process were obtained from the slop of the straight line corresponding to E vs. log i/id - i.Addition of flavonoides to a solution of Pb (II) ion, show the appearance of a new peak in a more negative potential than Pb (II) peak, with the gradual decrease in id of Pb (II) ion which suggests the complex formation between them.The stoichiometry and the stability constant of Pb (II) complex with flavonoids were calculated by Lingane equation; a plot of ?Ep vs. log [L] give a straight line, the slope of the line allows the determination of the coordination number (p), and the stability constant were determined from the intercept, the stoichiometry of these complexes were (1 : 1) with a stability constant of : Pb - Quercetine (5.5*107) ? Pb - Rutine (1.3*107) ? Pb - Hespertine (4*106) ? Pb - Chrysin (5.4*104)These measurements also includes the determination of the kinetic parameter of the electrode reaction (Kth, ?n) and the thermodynamic parameters such as ?H, ?G, and ?S.The spectrophotometric measurements were carried out in 50% methanol/water for Quercetin and Rutin, 30% methanol/water for Hespertin and in phosphate buffer of pH - 7 for Chrysin.The electronic spectrum of free flavonoides in methanol solution was mainly characterized by an important absorption band at ? 370 nm (band I) and a second one located at ? 256 nm (band II). Upon addition of lead (II) to the flavonoids solution significant changes are observed in the electronic spectra, a bathochromic shift in band (I) to the extent of ? 40 nm and a shift in band (II) to the extent of ? 7 nm, the change in ?max and the change in the intensities of the bands were due to the coordination between flavonoids molecules and Pb (II) ion.The stoichiometry of the formed complexes were investigated by the method of continuous variation and it were found (1 : 1), the stability constant were calculated also and were found to be in the order of ? 105 to 106.Thermodynamic parameters and kinetic studies were also determined which indicates a second order interaction between lead (II) and these flavonoides.Spectroscopic measurements for (EDTA) Complexation with lead (II) were carried out in order to compare its stability constant with that obtained for flavonoides complexes, due to its application in the treatment of metal poisoning.Stability constant of (EDTA) with Pb (II) complex were in the order of 108 which is much more efficient than flavonoides.
