Loading...

Theoretical Investigation of Hydrogen Bonding Effects on Interaction of Metal Nanoclusters with Histidine, Oxidation of Olefins by MnO4– & Acidity Enhancement of Alcohols

Jebeli Javan, Marjan | 2012

869 Viewed
  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 43608 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Fattahi, Alireza; Mahmoodi Hashemi, Mohammad; Jamshidi, Zahra
  7. Abstract:
  8. This thesis is divided into three parts: In part I, interactions of neutral and anionic forms of histidine with coinage metal nano clusters M3 (M = Au, Ag and Cu) are investigated. Results demonstrate that nonconventional M…H-O hydrogen bonds and M-X bonds (X = N, O) play stabilization roles in interactions of histidine and metal nano clusters. Presence of negative charge in ligand leads to increase of binding energy of complexes. In the next step, the effects of coinage metal nano clusters on the gas-phase acidity of weak organic acid (histidine) have been explored. The acidity of isolated histidine is compared with the acidity of its Au3–, Ag3– and Cu3–complexed species. Moreover, pKa values are determined in water for isolated and complexed species of His and His-OMe. Also, in order to investigate the nature of effective bonds in interactions, QTAIM and NBO analyses are used.In part II, The reaction pathway (including the transition state) of ethylene addition to permanganate in the presence of ethylene glycol (EG) has been qualitatively and quantitatively studied by means of B3LYP/6-311++G** theoretical analysis. Interestingly, by cluster formation of the EG with permanganate, oxidation reaction becomes thermodynamically and kinetically more favorable. The influences of electron-withdrawing as well as electron-donating substituents were also explored. Results of the quantum theory of atoms in molecules (QTAIM) and Natural bond orbital (NBO) analyses revealed that [3+2] addition reaction of alkenes in the presence of EG as hydrogen bonding donor to MnO4- becomes more exothermic. Natural resonance theory (NRT) is used to calculate natural bond order and bond polarity.In part III, effects of cooperativity of hydrogen bonds in acidity enhancement of polyols in two sections, are investigated in gas phase and dimethyl sulfoxide by means of theoretical methods. Polyhydroxylated piperidine and polyhydroxylated thiopyrans were selected as alcohol models in section 1 and 2, respectively. As expected, cooperativity of hydrogen bonds in these models shows drastic influence in acidities of these molecules. Linear correlation between gas phase acidity (GPA) and pKa in DMSO for model alcohols can be used for prediction of pKa for other alcoholic models.
  9. Keywords:
  10. Metallic Nanocluster ; Histidine ; Cooperative Hydrogen Bond ; Atom in Molecule Method ; Natural Bond Orbital (NBO) ; Permanganate

 Digital Object List

  • محتواي پايان نامه
  •   view

 Bookmark

No TOC