Alkylation and pre-organisation of diglycolamide ligands on flexible platforms for nuclear waste treatment

In this PhD work the synthesis and evaluation of new diglycolamide (DGA) ligands is described.

‘We aimed at developing new pre-organised   ligands with improved extraction and separation efficiency of actinide and lanthanide ions,’ says Andrea Leoncini. ‘We focused on the preparation of rather simple, easily accessible and completely incinerable ligands, to be used in various processes in the nuclear waste industry.’

According to Andrea a total volume reduction of most nuclear waste flows of ninety percent is thinkable. ‘In many cases, the percentage of problematic radioactive waste volumes can be reduced to less than one percent,’ he says. ‘As a boundary condition, first certain groups of metals have to be removed. After that, transformation of the radioactive material in less hazardous (and with shorter half-lives) isotopes, and even recycling rare earth materials from nuclear waste, comes within reach.’

Andrea’s thesis work first dealt with small modifications of the backbone of TODGA (tetraoctyldiglycolamide). Its influence on the extraction and degradation behaviour of the ligands, was determined.

‘We highlighted that even steric interactions between small methyl groups can have significant impact on the performance of the ligands,’ Andrea says. ‘This was a very nice and surprising result, for me as well as for my colleague researchers in the field. Diastereomeric compounds show quite some distinctive chemical and physical properties, but we didn’t expect to observe such big differences.’

Andrea published his findings in Dalton Transactions Journal, New Journal of Chemistry, and Chemical Society Reviews.

‘Publishing in the last-mentioned journal was especially rewarding,’ Andrea says. ‘The article was accepted quite quickly. I reported the recent developments of these classes of ligands, focusing on the last six years, but sometimes going back as far as the ‘70s. It was quite an effort.’


His PhD work may be valued as: ‘the step after the first fundamental findings,’ Andrea explains. ‘New insights have been gained and can be added to the knowledge available. Some ligands look promising and are now well qualified for further research, for example to further study their hydrodynamic properties. Before implementation in industrial settings also cost calculations are to be made.’


Some insights which may potentially lead to the development of more selective ligands, include the interplay between the platforms used and the solvent systems, and also the flexibility of the platforms.

‘Ultimately more environmentally friendly processes and long-term storage strategies are necessary,’ Andrea says. ‘Be it in industry or in academic research; one of my most important personal motives will be to contribute to society and for the good of the environment we live in.’


As a member of the Molecular Nanofabrication Group (MNF), Andrea worked on this topic within a European consortium, including fellow-researchers from the UK, Germany, France and Spain. ‘All groups within this fairly small international community, have a specific approach towards solving nuclear waste issues,’ Andrea says. ‘In my opinion Mesa+ shows a good contribution internationally.’

During his PhD Andrea learned to work on multiple subprojects in parallel. ‘Prioritizing and scheduling carefully one’s proceedings is vital. As a researcher you have to come up with new and creative ideas. In this project, for example, alternative ideas were found to transcend currently used column chromatography techniques, to purify the compounds needed. ‘

‘I collaborated with labs based in India, specialized and certified to perform experiments involving radioactive material. Actively seeking collaboration is an important part of modern scientific research.’


Andrea favours an academic career a little above one in industry, because of the educational tasks which he likes very much. ‘A post-doc project in Europe would be a nice challenge,’ he shares. ‘I enjoy being a tutor and teacher in my disciplinary field, to transfer and communicate my passion for research.’