Dinamika vode i tuneliranje vodika u protonom spregnutoj reakciji prijelaza elektrona

doctoral thesis

• Title (english): Water dynamics and hydrogen tunnelling in proton-coupled electron transfer reaction
• Author: Ana Karković Marković
• Mentor: Stanko Uršić (mentor); MBZ: 51201
• Committee member: Hrvoj Vančik (predsjednik povjerenstva)
• Committee member: Stanko Uršić (član povjerenstva); MBZ: 51201
• Committee member: Davor Kovačević (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Chemistry); Zagreb
• Defense date and country: 2016-10-17, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Chemistry; Physical Chemistry
• Universal decimal classification (UDC): 54 - Chemistry. Crystallography. Mineralogy

Abstract

Istražen je ucinak djelomicno hidrofobnih molekula (organskog otapala i kvarterne amonijeve soli) na protonom spregnuti prijelaz elektrona (PCET) u reakciji askorbata s heksacijanoferat(III) ionom u vodenoj sredini, te je opažen prijelaz iz aktivacijskog režima u režim tuneliranja, dodatkom organskih otapala i kvarternih iona. Eksperimentalna opažanja koja ukljucuju povecane vrijednosti kinetičkog izotopnog učinka (KIE) u odnosu na reakciju u vodi, izotopne omjere AH/AD Arrheniusovih predeksponencijalnih faktora znacajno manje od semiklasično predviđenih, kao i izotopne razlike aktivacijskih energija procesa veće od semiklasičnih, objašnjena su u okviru markusianskog modela tuneliranja koji uzima u obzir dinamičke aspekte sustava i okoliša. Prijelaz protona dinamički je povezan s femtosekundnom dinamikom OH skupine vode. Dodatak djelomično hidrofobnih molekula u vodenu sredinu dovodi do promjena dinamike OH vode zbog interakcije s hidrofobnim dijelom molekule i ta promjena intermolekularnim rezonantnim vibracijskim mehanizmom uključuje molekulu vode u prijelaznoj konfiguraciji i promotivne vibracije povezane s reakcijskom koordinatom protonsko-elektronskog prijelaza u procesu.

Abstract (english)

The influences of molecular hydrophobic interfaces, involving organic solvents and quarternary ammonium ions, on the proton-coupled electron transfer (PCET) reaction of ascorbate monoanion with hexacyanoferrate(III) ion in water has been investigated. The kinetic isotope effect (KIE) in the reaction and the isotopic differences in Arrhenius activation energies increased and the isotopic ratios of the corresponding pre-factors AH/AD decreased significantly, suggesting a change from the apparent over-the-barrier process in neat water to a tunnelling regime on involving hydrophobic interfaces in the water solvent system. The observed phenomena are ascribed, invoking a Marcus-like tunnelling model that includes dynamical aspects of system and surroundings, to hydrogen tunnelling in reaction dynamically connected with femtosecond motions of water OH, where presence of hydrophobic interfaces causes changes in water dynamics coupled with reaction coordinate of the PCET process through intermolecular vibrational coupling mechanism of water.

• Keywords: dinamika vode; hidrofobnost; promotivna vibracija; protonom spregnuti prijelaz elektrona; tuneliranje vodika
• Keywords (english): hydrogen tunnelling; hydrophobicity; promoting vibration; proton-coupled electron transfer; water dynamics
• Language: croatian
• URN:NBN: urn:nbn:hr:217:690564
• Study programme: Title: Doctoral study in chemistry; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, područje prirodnih znanosti, polje kemija (doktor/doktorica znanosti, područje prirodnih znanosti, polje kemija)
• Type of resource: Text
• Extent: 149 str. ; 30 cm
• File origin: Born digital
• Access conditions: Open access
• Created on: 2017-02-02 16:48:17