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Identifier 000398949
Title Design and synthesis of porphyrins and their effect in laccase's activity for the catalysis of dioxygen reduction
Alternative Title Σχεδιασμός και σύνθεση πορφυρινών και η επίδρασή τους στην δραστικότητα της λακάσης για καταλυτική αναγωγή οξυγόνου
Author Πέτρου, Αθανασία Ν.
Thesis advisor Κουτσολέλος, Αθανάσιος
Tron, Thierry
Reviewer Μήλιος, Κωνσταντίνος
Abstract In recent years, great effort has been devoted to the development of new technologies for catalyze reactions using solar energy as a sole source of energy. Several publications have appeared documenting approaches where an association of enzyme (catalyst) and photosensitizer, [1-4] allow performing redox reactions such as O2 oxidation or H2 reduction. In addition, a separate area of research, focuses on design of photo-driven systems using photosensitizer and enzyme for catalyzing chemical transformations using water or dioxygen as oxygen atom source [5]. However, there are many factors such as the necessary presence of sacrificial electron acceptor and inert conditions or the production of reactive oxygen species which should be considered. Therefore, the design of a photocatalytic system that could potentially use the atmosphere’s dioxygen as the final electron acceptor, in such catalytic systems, is of major importance. In the present study, we describe the design of hybrid photocatalytic systems consisting of photosensitizers and an enzyme (laccase) co-absorbed on TiO2 nanoparticles. These systems are designed to catalyze visible - driven oxidation of organic substrates, e.g. an alkene to epoxide, with O2 as oxidant, under mild conditions, at room temperature. Porphyrins, corroles and RuP were selected as photosensitizers. The effectiveness of nine different photosensitizers, free base and metallated, bearing phosphonate and carboxylate anchoring groups, linked either directly or through alkyl chains at p-position of their peripheral phenyl groups was investigated in this study. Porphyrins, corroles as well as RuP [3] appear of high stability, high absorption in the visible spectrum and having long life time in their excited states. On the other hand, the enzyme laccase belongs to the family of multicopper oxidases which couple the oxidation of a wide range of organic or inorganic compounds with the concomitant reduction of O2 to water [6]. At first, dioxygen comsumption experiments were performed with all the photosensitizers and the best ratios of both photosensitizer and laccase leading to optimal performance were identified. RuP and porphyrins bearing carboxylate and phosphonate groups at the p-position of their peripheral phenyl groups showed the best performance. Taking into consideration the results of dioxygen consumption measurements, the best performing photosensitizers were also studied for their potential use in the photocatalytic oxidation of p-styrene under mild conditions. Unfortunately, none of our system displays photocatalytic activity during visible-light driven oxidation of organic compounds
Language English
Subject Dioxygen reduction
Multi-copper oxidases
TiO2 nanoparticles
Αναγωγή μοριακού οξυγόνου
Νανοσωματίδια TiO2
Πολύ-πυρηνικές οξειδάσες χαλκού
Σύμπλοκο ρουθηνίου
Issue date 2016-03-18
Collection   Faculty/Department--Faculty of Sciences and Engineering--Department of Chemistry--Post-graduate theses
  Type of Work--Post-graduate theses
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