Aromatic H/D exchange reaction mechanism in water solution (Master thesis)

Χαλκίδου, Φωτεινή


The objective of this MSc thesis is the investigation, with the use of proton NMR spectroscopy, of the catalytic role of H2O in the direct activation of aromatic C–H bonds without the use of late transmission metals. H/D exchange reactions, as monitored by 1H NMR, were achieved with the use of D2O and common phosphate buffer at neutral pH and near ambient temperatures. The unique catalytic role of H2O, through keto-enol tautomerization, was demonstrated with DFT theoretical calculations. Specifically, taxifoline, naringenin and eriodictyol were structurally characterized with the use of 1D 1H, 2D 1H-13C HSQC, 1H-13C HMBC, 1H-1H NOESY NMR spectroscopy and DFT theoretical calculations. The structural data of taxifolin were compared with the single crystal X-ray structure. Taxifolin – bovine serum albumin (BSA) complex was studied by the use of STD and tr-NOESY NMR spectroscopy. Detailed studies of Taxifolin’s C-6 and C-8 H/D exchange reaction was kinetically and thermodynamically studied by using 1D 1H NMR, in various temperatures (10-55 °C), pD=7.6 & 9.6 and phosphate buffer solution (2.5mM, 25mM, 50mM, special value 1M). The experimental results were confirmed by DFT theoretical calculations. The results of the thermodynamic approach in combination with the DFT theoretical values clearly demonstrate the unique catalytic role of water. As a result a new molecular mechanism was proposed.
Alternative title / Subtitle: δομική, κινητική και θερμοδυναμική προσέγγιση με NMR
structural, kinetic and thermodynamic NMR-based approach
Institution and School/Department of submitter: Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας
Subject classification: Φλαβονοειδή
Keywords: Πυρηνικός μαγνητικός συντονισμός,Φλαβονοειδή,Ανταλλαγή πρωτονίου/δευτερίου,Καταλυτικός ρόλος Η2Ο,Κατάλυση με νερό,Nucler magnetic resonance (NMR),Flavonoids,Proton/deuterium exchange,Catalytic role of H2O,Water catalysis
URI: http://olympias.lib.uoi.gr/jspui/handle/123456789/28163
Appears in Collections:Διατριβές Μεταπτυχιακής Έρευνας (Masters)

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