Periodic Reporting for period 1 - PECaN (Photo-ElectroCatalysis: New activation paradigm)
Okres sprawozdawczy: 2020-05-01 do 2022-04-30
One of the main problems that is currently being tackled by researchers in chemistry is how to perform reactions selectively. This means, that only the required product is formed, and all other possible reaction pathways leading to degradation of the materials, or formation of side products have to be suppressed. This minimizes the waste and makes separation of the products simple – a hallmark of a successful industrial process. Organic chemical compounds are generally quite stable. In order to engage them in reactions, we need to give them energy – activate them. Traditionally, this has been accomplished by heat, as increased temperature also increases the reaction kinetics. Unfortunately, this approach is in odds with the desire for high selectivity, as the increased temperature speeds up also the unwanted reactions, often leading to decomposition of starting materials and products in the process. The way to overcome this difficulty is catalysis. Currently photocatalysis and electrocatalysis show great promise in development of new reaction processes, alongside with the recently discovered piezoelectric catalysis. These approaches utilize external energy – light (photocaltaysis); electric current (electrocatalysis); mechanical force (piezoelectric catalysis) – and transfer this energy via catalyst to the molecule which we want to activate. Using this approach, we can circumvent the necessity for elevated temperatures, allowing for activation of molecules under mild conditions. Furthermore, renewable energy of sunlight can be used for this purpose, either directly (photocatalysis) of indirectly. This project aims to utilize these activation modes for activation of small organic molecules, leading to their selective transformations. In order to be able to develop efficient processes, we must understand the reaction mechanism. State-of-art quantum-chemical calculations will be used for this purpose.
The project consisted of four work packages – WP1-WP4. The focus of the WP1 was investigation of reaction mechanisms by quantum-chemical calculations. This is an indispensable tool for mechanistic study, as the intermediates involved often do not live long enough to be studied by experimental techniques of physical chemistry. In combination with experimental techniques used by our collaborators, we were able to elucidate reaction mechanisms, including mechanisms in excited state. In one case, this approach was used in combination with statistical treatment of the data to identify parameters influencing the reaction outcome. Tasks in WP2 and WP3 were centered around experimental utilization of new methods of activation of small organic molecules, with the focus on piezoelectric catalysis. Most importantly, very cheap, available and simple inorganic materials were identified as competent piezoelectric catalysts. Various reactions such as isomerizations, borylations and radical cyclizations were successfully performed using these conditions. Serendipitously, we have also discovered the activity of simple table salt - NaCl in triggering reactions of diazonium salts in a ball mill. Mechanism of this process was explained by a combined computational-spectroscopic study. As a part of WP4, we have developed a new catalyst framework based on nitrogen-containing heterocycles, which can be used in photo-redox catalysis and photo-electro catalysis. A variety of electrochemical and photochemical experimental techniques was used to find the optimal substitution pattern on the catalyst core.
The scientific results from this project were already published in 3 peer-reviewed articles, with another article submitted, another in writing and 2 other planned. Furthermore, results obtained in this project were used as a cornerstone for a ERC StG application, that has already successfully passed the 1st round of evaluation, and is currently evaluated in the 2nd round.
The scientific results from this project were already published in 3 peer-reviewed articles, with another article submitted, another in writing and 2 other planned. Furthermore, results obtained in this project were used as a cornerstone for a ERC StG application, that has already successfully passed the 1st round of evaluation, and is currently evaluated in the 2nd round.
New materials were obtained to be used in piezoelectric catalysis as well as photo-electro catalysis. A series of guidelines for development of catalysts for photocatalysis and photoelectrocatalysis by repurposing catalysts with known activity as electrochemical mediators was established, with potential to expedite discoveries in this field. This project was completed at a major research university in Slovakia – a widening country of the EU, and will have lasting effects on its research capacity: New intra-EU collaborations were established, closing the gaps between different research systems, which is in line with recommendations of the European Committee (furthering internationalization of the Slovak research landscape was recommended). Joint international grant proposals based on these collaborations are already submitted. Furthermore, due to involvement of students in this project, it will also lead to increased proficiency of younger generation of chemists in the quickly growing field of redox catalysis. The fellow was extensively involved in outreach activities targeted at high school population during the course of this project, leading to increased interest in chemistry and other research-heavy natural sciences within the cohort of future university students, aiming to increase the amount of students in these fields, which play a key role in European economy.