On the 23rd of October, the building that has been the home to the Institute of Chemistry of the University of Tartu – Chemicum – turned 15 years old!
To celebrate the special occasion, all the Chairs of the Institute prepared various dishes showcasing some of their research fields. Of course, our Chair of Analytical Chemistry was also present with a special cake – a pH cookie cake!
The cookie cake was 100 x 40 cm large and consisted of classical layers of whipped cream mixed with curd, chopped bananas and cookies.
The main attraction was the decorative top layer, where we used colourful fruits and berries to visualise the pH and pKa scale with the typical colour gradient.
In addition, some structures of acids and bases made from chocolate were added as representative examples.
The making of the cake turned out to be a fun group activity, which is best seen in the gallery below.
The making of the cake turned out to be a fun group activity, which is best seen in the gallery below(or click here for the full gallery).
We are happy to announce that Ester Oras, Associate Professor in our Analytical Chemistry Chair and PI of the Archemy group has received the honorary title “Female Academic of the Year” from the Estonian Association of Academic Women!
Ester Oras. Photo: Andres Tennus
Ester is a modern scientist who works across multiple disciplines, integrating methods from archaeology, chemistry, biology, and even food science. Her research is primarily focused on ancient diets in Northern Europe, particularly in Estonia. Through this work, she established the first archaeochemistry lab in the Baltic region called “Archemy” at the Univeristy of Tartu. Her studies focus on ancient food practices — what people ate, how diets varied between social classes, and how food was tied to broader economic and cultural systems. She has also applied her expertise in archaeochemistry to investigate topics such as ancient migrations and Stone Age crafting technologies.
At the same time, Ester’s research extends well beyond Estonia. She has trained at leading research institutions worldwide, including Oxford, Cambridge, Max Planck Institute, and Weizmann Institute, mastering advanced analytical techniques like mass spectrometry and chromatography. Internationally regarded as an expert in the biomolecular analysis of food remains, she collaborates with researchers from countries like Germany, Finland, and the UK. Her work has been published in over 50 scientific articles across top journals in archaeology and natural sciences. In recognition of her groundbreaking research, she was recently awarded the prestigious ERC Starting Grant, and she holds several international leadership roles in organizations such as the International Society for Biomolecular Archaeology.
Beyond her scientific work, Ester is deeply committed to public outreach and gender equality in science. She regularly speaks at schools, museums, and on television, raising awareness about archaeology and inspiring future generations of scientists. She is an advocate for women in science, having launched also in Estonia the celebration of the International Day of Women and Girls in Science and contributing to numerous international gender equality projects. Her leadership extends to the University of Tartu, where she has been part of developing the university’s gender equality plan and growing a more inclusive academic environment. Through her interdisciplinary research, international collaborations, and dedication to social issues, Ester is shaping both the future of science and the role of scientists in society.
Congratulations on this well-deserved recognition, Ester!
Märt Lõkov works in our group focusing on investigations of acid-base equilibria – first of all, determination of acidity and basicity constants (pKa values) of molecules – in nonaqueous solutions. This is a core research direction in our group and he is one of the key people in advancing it.
He has made significant contributions to the self-consistent acidity scaleand self-consistent basicity scalein acetonitrile, containing pKa values 231 acids and pKaH values of 279 bases, respectively. Because of how these values have measured (“multiple overlapping” relative spectrophotometric measurements), these scales are widely regarded as the most reliable sets of pKa values in acetonitrile. Thus, assembling those scales was to a large extent also a revision of existing pKa values for many compounds and assigning new values to them.
Märt has mastered the art of pKa measurements in nonaqueous media to the highest degree and is right now one of the most skilful people on planet Earth in performing nonaqueous pKa measurements. Besides doing these measurements himself, he has supervised and is supervising numerous master’s and doctoral students who measure pKa values in their degree projects. Thus, indirectly, via the supervised students, his contribution is even larger.
Perhaps the most ambitious endeavour that Märt is now engaged in is a large-scale re-evaluation and revision of pKa values of carboxylic acids in three nonaqueous solvents – acetonitrile, DMSO, dimethylformamide. The analysis of available pKa data that we have carried out in the framework of the IUPAC project 2015-020-2-500 Critical compilation of acid pKa values in polar aprotic solventsreveals that the non-aqueous pKa values available in the literature for this very important compound class are often significantly in error, sometimes by several orders of magnitude. The revision will involve measurements and analysis of literature data. Märt has assembled a group of people involving several students and the expected outcome will be a large amount of high-quality nonaqueous pKa data of carboxylic acids.
We’re delighted to share that members of our Archemy and Analysis of Cultural Heritage Objects groups have published a new article titled, “Influence of Mineral Composition and Firing Temperature on the Micro- and Mesoporosity of Replicate Archaeological Ceramics” in the journal of Clays and Clay Minerals (Volume 72, 2024, e13). Read the Open Access article here.
This study examines how the mineral composition of clay and temper, along with firing temperatures, influences the formation of micro- and mesopores in pottery. The porosity of ceramics is considered a significant factor in the absorption and preservation of organic compounds, such as lipids, within archaeological pottery. Our research provides the first quantitative analysis of pore structures in ceramics designed to replicate archaeological samples, establishing valuable baseline information for future investigations into ceramic porosity and organic residue analysis.
On the 5th of September 2024, PRG workgroup members Dr Signe Vahur, Dr Anu Teearu-Ojakäär, Dr Rünno Lõhmus, Dr Aleksei Treštšalov and specialist MSc student Martin Leissoo visited the Mitutoyo metrology lab at Riga Technical University (RTU) where the director of the lab Ass. Prof. Janis Lungevics kindly hosted them and introduced different new equipment in the lab.
From left: Rünno, Aleksei, Janis, Signe, Martin, and Anu
The one-day trip was undertaken for the purpose of research work. As part of the collaboration, various materials related to the PRG project have been measured with an optical 3D profilometer in Mitutoyo’s laboratory. Janis introduced the 3D profilometer and showed also very interesting research results that will be published in the joint scientific article.
All the members of the PRG group were very excited about the visit, which gave new interesting ideas for further research.
Thank you, Janis, for a very interesting day and all the support and help!
Janis demonstrating the power of the 3D profilometer
The presentation started with how acid and base strengths, typically expressed as pKa values (acids) or pKaH values (bases), depend on solvation of the proton, as well as of the neutral and ionized forms of the acid/base. Every solvent has different solvation properties. Thus, the pKa values for the same acid/base in different solvents are also different (often dramatically different).
In principle, whenever using pKa values for predicting or rationalizing chemical processes, the pKa values determined in the same solvent should be used. In some solvents, e.g. water, DMSO or acetonitrile large bodies of pKa data exist, while in most solvents either very few pKa values are available or none at all. This leads to the frequent need of estimating pKa values in one solvent from the data in other solvent(s) (Picture on the right). An additional consideration is the (often problematic) quality of pKa data in the literature.
When estimating pKa values in one solvent based on the data in another solvent it is important to clearly define the aim. Is it needed to have the absolute pKa value or is it rather necessary to have the acidity/basicity differences (or acidity/basicity order) within a set of compounds? Perhaps the question is just “can base B deprotonate acid A in solvent S”? If absolute pKa value is needed then what accuracy is necessary? Depending on the aim, there are different possibilities of estimating pKa and pKaH values in a solvent on the basis of data in other solvents.
The presentation gave an overview to what extent such estimates can be usefully done, highlighting both successes and failures, as well as how to recognize clearly erroneous pKa data. The presentation also highlighted the IUPAC project Critical compilation of acid pKa values in polar aprotic solvents that is nearing completion. The critically evaluated pKa data of acids in dimethyl sulfoxide, acetonitrile, N,N-dimethylformamide, pyridine, acetone, propylene carbonate, tetrahydrofuran are available from Ivo Leito on request.
The presentation turned out to be highly interesting for the participants, receiving a large amount of questions, which extended well into the coffee break!
(This research was supported by grant PRG690 from the Estonian Research Council)
We are delighted to announce that the prestigious ERC Starting Grant was awarded to a member of our group and head of the Archemy team – Associate Professor in Analytical Chemistry and Archaeology Ester Oras!
Ester Oras. Photo: Andres Tennus
The European Research Council (ERC) Starting Grant is awarded to early-stage researchers to carry out their outstanding ideas over the next five years. Ester’s project aims to explore our distant ancestor’s identities through diet by conducting biomolecular analysis on at least 150 burial finds, uncovering details of life from a thousand years ago.
Food is a crucial element in understanding identity, revealing details about social roles, status, and even how the person spent their childhood. By examining bones, teeth, and food residues from pottery, the team can reconstruct how a person’s diet evolved over their lifetime. This will help answer questions like whether an individual ate foods typical of their gender or social class and if they grew up in the area where they were buried.
During the project, various burial finds will be analysed, focusing primarily on sites in Estonia from the years 1000–1400. Using advanced techniques, the team will analyse various molecules, including fats, proteins, and DNA, to uncover specific details about what ancient people ate. This comprehensive approach could even identify not only if the person ate fish but also whether it was cod or herring, offering a deeper look into the lives of our ancestors.
What makes this research groundbreaking is its combination of modern scientific methods with traditional archaeology. Machine learning will be used to integrate the results from various analyses, helping to identify connections between individuals and communities. The project marks a significant step forward for archaeological research, offering new perspectives on ancient identities and social structures.
We are excited to share our latest publication titled, “pKaH values and θH angles of phosphanes to predict their electronic and steric parameters” (Dalton Trans., 2024, 53, 14226-14236. https://dx.doi.org/10.1039/d4dt01430h).
In this study, we delve into the fascinating world of phosphanes – a versatile class of organic bases that play a crucial role in a wide array of chemical applications. Phosphanes are known for their incredibly diverse range of basicities, with pKaH values spanning over 30 orders of magnitude. One of the key insights from our research is that pKaH values can be a valuable alternative to Tolman electronic parameters (TEP values) for assessing the electronic properties of phosphanes. This finding opens up new possibilities for researchers to evaluate phosphanes without the need for the time-consuming preparation or calculation of metal-ligand complexes.
In addition to electronic properties, we also propose new geometric parameters to assess the steric properties of phosphanes – the θH angles, which have the advantage of being accessible by simple computations. Together, the pKa values and θH angles provide a straightforward approach to understand and predict the behavior of phosphanes in various chemical environments and processes.
Our study combines computational and experimental findings to offer a fresh perspective on how phosphanes can be analyzed and utilized, and we believe it will be a valuable resource for researchers working with these compounds. We invite you to read the full article to explore the detailed findings and implications of our work.
From June 2 to June 6, 2024, Signe Vahur and Anu Teearu-Ojakäär attended the 72nd ASMS conference on mass spectrometry and allied topics at Anaheim Convention Center (Anaheim, USA).
Signe and Anu at ASMS
This year, the conference hosted almost 6800 attendees and 183 companies. During the four days there were 384 oral presentations that ran in 8 parallel sessions and 3288 poster presentations (more than 800 posters per day) on wide variety of topics related to mass spectrometry – developments in instrumentation, analysis of complex and problematic samples, using AI and software solutions to improve measurements, data handling, etc. In addition, there were 50 evening workshops and 49 breakfast seminars. From Monday to Wednesday evening, 15 daily corporate hospitality suits were hosted by some of the companies (e.g., Bruker, Agilent Technologies, Shimadzu, Thermo Scientific, etc.).
Anu and Signe in front of their poster
At the conference, Signe and Anu presented their poster “APCI-MS for the analysis of cultural heritage materials” during the Thursday (June 6) poster session. On Monday evening (June 3), Anu gave a 3-minute Flash talk at the evening workshop “Art, Museums, and Archaeology” for an audience of approximately 160 attendees.
Anu giving a Flash presentation
The 72nd ASMS conference was a great experience by meeting old colleagues and fellow MS enthusiasts, making new connections, having great and fruitful discussions and networking opportunities. Thank you to the organisers of the conference for delivering yet another high-level event!
This dissertation begins with the observation that while polymer membrane ion-selective electrodes (ISEs) have been well known and widely used for decades to detect small cations, determining organic anions with ISEs remains a challenge, essentially without a solution. The dissertation presents a journey starting with the study of the interactions between small monocarboxylates and numerous anion receptors – potential new ionophores.
By measuring the binding constants of eight carboxylates (formate, acetate, pivalate, lactate, ibuprofen, ketoprofen, glucuronate, and benzoate) to 44 synthetic receptor molecules using nuclear magnetic resonance, Kerli constructed eight binding affinity scales where all the binding affinities are comparable. These results were then assembled into a large overall map of the receptor-anion binding constants (Figure on the right). The results revealed that the selected synthetic hydrogen-bond donor receptors can distinguish between carboxylates with different structures.
As a result of this binding study, a 1,3-bis(carbazolyl)urea derivative (receptor 13 in the Figure on the right) was selected as the hydrogen-bonding ionophore to create prototypes of ion-selective electrodes that can detect acetate. The electrodes built by Kerli displayed a unique selectivity pattern for different anions. The addition of this ionophore to the electrode membrane significantly (by up to several orders of magnitude) reduced the interference from other common ions such as chloride, bromide and nitrate. Kerli’s work is an important step forward in designing ionophores that can specifically bind carboxylates and building sensitive and selective ion-selective electrodes for different anions.
The defence procedure itself was quite a battle for Kerli! It started with the detailed questioning by the opponent prof. Claudia Caltagirone (University of Cagliari, Italy) on all the aspects of the thesis. Particularly interesting and difficult were some of her highly technical questions regarding the fluorescence measurement of binding affinities. Then there was a long string of questions from the defence committee members. The topics of Kerli’s thesis ranged from receptor-anion binding to computational chemistry and from materials science to hard-core electrochemistry. Thus, most committee members found something familiar and worth asking about. Kerli managed nicely with all the questions and left a very good impression on everybody in the room!
On the 23rd of October, the building that has been the home to the Institute of Chemistry of the University of Tartu – Chemicum – turned 15 years old!
In addition, some structures of acids and bases made from chocolate were added as representative examples.
