The IV PhD degree and PhD special prize award ceremony will take place on November 24, 2017.
Màrius thesis, entitled "Explorant noves propietats electroquímiques dels metal·lacarborans. estratègies per a l’heterofuncionalització i aplicacions en biologia molecular", won in 2015 the Sant Jordi Award "Premi IEC de Ciències Químiques Antoni de Martí i Franquès" for the best thesis written in Catalan.
His PhD research focused on the synthesis and characterization of metallacarboranes (organic clusters with boron, carbon and metal ions), and their interaction with living cells.
About the thesis
Màrius Tarrés' thesis deals with cobalt and ferrabisdicarbollide metallacarboranes ([3,3’-Co(1,2-C2B9H11)2]-, -; and [3,3’-Fe(1,2-C2B9H11)2]-, -, respectively), anionic and redox reversible compounds, used as starting point and final target.
The first section of the Thesis is focused on the search for an efficient strategy to regioselectively functionalize a simple platform with different kind of metallacarboranes (- and -), with good yields and easy purification processes. A very clean, high-yield and efficient synthetic pathway has been found: the malonic and acetoacetic ester synthesis. Following this synthetic route, the homo and heterosubstitution has been obtained, achieving for the first time the heterofunctionalization of a single platform with - and -, with high yields.
The second chapter of the Thesis is referred to the electrochemical properties of metallacarboranes. The redox potential determination and modulation of the differently substituted metallacarboranes, by means of cyclic voltammetry, has been widely studied here. The E1/2 of the metallacarborane platform has been broadened up to 2 V for the first time, by sequential iodinations of its B-H vertexes. In addition, electrolysis experiments have been carried out, trying to understand and demonstrate the reversibility and stability of the generated reduced and oxidized products, respectively. Moreover, they turned to be good polyelectrochromic materials when coupled with methyl viologen. Furthermore, a last study in this same chapter demonstrates the fluorescence quenching ability of metallacarboranes, and the influence of the charge, E1/2 and electronic configuration of these boron cluster compounds in terms of quenching efficiency.
The third section is related to interactions and ionic affinities of metallacarboranes in aqueous solution. This chapter is focused on double metallacarborane molecules connected by different polyethoxylated chains (dumbbell-like), and their ability to “embrace” different cations. In this study, alkaline cations have been tested, being the larger ones (K+ and Cs+) the preferred and the ones that better fit the electronic and steric requirements of the different metallacarborane-dumbbells; while the smaller ones (Li+ and Na+) are clearly less favored. At last, but certainly not least, the fourth chapter deals with the interactions of - and its diiodinated derivative, -, with living cells.
Bearing in mind the water solubility and intermolecular interactions of such compounds, molecular biology studies with mammalian cells, amoebas and bacteria have been carried out. The first results confirmed the penetration of metallacarboranes inside living cells, producing an immediate rounding of the cell shape. The distribution of the boron-based compounds inside the cells turned to be heterogenic, suggesting some kind of interaction with specific internal parts of the cells. Strikingly, the cells in touch with the boron compounds stopped their cell division activity, and recovered it once the compound is removed from the medium. Additionally, high loads of the metallacarboranes do not kill cells, confirming that the clusters are not directly toxic. It has also been demonstrated that the citostatic effect is more or less effective depending on the studied cell, but in all cases - turned to be more potent/efficient than -. Besides, no chemical modifications or degradations have been observed on the used metallacarboranes, recovering the original compounds at the end of the experiments, enabling them for further uses.
About the PhD special prize award ceremony
With 66 PhD programmes, the UAB is one of the leading Catalan universities in the production of theses and generates approximately a third of the doctoral theses that are defended in the Catalan university system each year.
With the PhD degree and PhD special prize award ceremonies, which are held twice during the academic year (around May and November), the UAB demonstrates its appreciation for the effort and dedication of young researchers and their contribution to the generation of knowledge. The event is organized by the School for Doctoral Studies and the UAB Alumni.
The main value of the UAB is its human capital and the new doctors are an essential element for the continuation of excellent lines of research. That excellence is based on the quality of the PhDs as a distinctive indicator.
The PhD special prizes confer value to theses which have received the qualification of excellence "Cum Laude" and which, having been proposed by the Admissions Committee of each academic programme, stand out for their contribution and advance in the different areas of our University. The prizes are awarded per academic year, in accordance with PhD regulations and with the criteria specified in each PhD programme.