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Theoretical Investigation of Hydrogen Bonding Effects on Interaction of Metal Nanoclusters with Biomolecules & Acidity Enhancement of Alcohols

Ali Akbar Tehrani, Zahra | 2012

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 43133 (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, conformational properties of neutral, anionic, cationic and zwitterionic forms of glutathione tripeptide were investigated by means of DFT-B3LYP method with 6-31+G (d,p) basis set. Results show that glutathione is a very flexible molecule and its conformational energy landscape is strongly influenced by forming intramolecular hydrogen bond and its charge. Conformation of each amino acid in glutathione tripeptide depends on its orientation within the peptide sequence in addition to the conformation of other amino acids within the chain. Investigation of intramolecular hydrogen bonds in these conformers by means of AIM analysis demonstrates electrostatic covalent nature for these bonds. In part II, interactions of neutral and anionic forms of glutathione with Au3 cluster and neutral form of glucose with coinage metal nano clusters (including gold, silver and copper atoms) are investigated. Results demonstrate that nonconventional M…H–O hydrogen bonds and Au-X bonds (X = N, O, S) play stabilization roles in interaction of these molecules and metal nano clusters. Presence of negative charge in ligand or positive charge in metal clusters lead to increase of binding energy of complexes. Moreover, for investigation of nature of effective bonds in interactions AIM and NBO analyses are used. In part III, effects of cooperativity of hydrogen bonds in acidity enhancement of polyhydroxylated pyrans as alcohol models are investigated in gas phase and Dimethyl Sulfoxide (DMSO) by means of theoretical methods. As expected, cooperativity of hydrogen bonds in these models shows drastic influence in acidities of these molecules. Linear correlation between gas phase acidity (∆Hacidity) and pKa in DMSO for model alcohols can be used for prediction of pKa for other alcoholic models
  9. Keywords:
  10. Glutathione ; Glucose ; Biosensor ; Metallic Nanocluster ; Cooperative Hydrogen Bond ; Atom in Molecule Method ; Natural Bond Orbital (NBO)

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