九州影院

Q&A with Nonheme iron-oxo oxidants

What was your role within the team?

Larry Que: Of the three PIs in this team, I represent expertise in the more chemical and biochemical aspects of this field of metallobiochemistry and have the longest tenure in academic life among the three of us.

Bittu Chandra: I contributed to the design and execution of the study on the distinct H-atom and O-atom transfer reactivities of oxoiron(IV) topological isomers, performed data analysis, and participated in manuscript preparation.

Jin Xiong: I conducted the spectroscopic analysis together with Prof. Guo, including 57Fe M枚ssbauer and continuous-wave EPR spectroscopy, to elucidate the electronic structure of these complexes. I also contributed to the theoretical thermochemical analysis.

Yisong Guo: Together with my post-doctoral associate Dr. Jin Xiong, I performed the spectroscopic studies on these unique oxoiron(IV) complexes. Our research expertise lies in using multiple spectroscopic techniques 鈥� such as M枚ssbauer, EPR, and synchrotron radiation-based spectroscopic techniques 鈥� to explore electronic structures of transition metal complexes, including high-valent iron complexes.

Marcel Swart: Coordination of the computational chemistry part and connecting its results with the experimental data. As Larry Que usually started his conversation when we discussed a new project: 鈥淲e have these new data. But how does it work?鈥�

Abhishek Das: My role within the team is mostly to design and synthesise new systems with small differences in second coordination sphere to get useful insight on various parameters which can influence the reactivity of high valent iron(IV)-oxo complexes.

Mehmet Jahja: I would qualify my role as being a minor one in this consequent project. With the help of my friend Sami, we supported Prof. Swart with theoretical calculations on iron complexes being either in triplet or quintet spin states.

What were the biggest challenges in this project?

Bittu Chandra: One of the biggest challenges was uncovering the mechanism behind the dramatic reactivity differences between two topological isomers of a nonheme Fe(IV)=O complex, caused by a simple flip in its orientation relative to the macrocyclic tetraamine host.

Abhishek Das: The biggest challenges were to point out the factors behind the observed trends for these series of new complexes.

Marcel Swart: With computational chemistry one can, in theory, explain everything. But real life is often different, either because of the spin states involved, or because the system sizes are so large that density functional theory (DFT) calculations take several weeks to several months to finish. And then the DFT results have to match with experimental spectroscopy data and reaction rates of course. Luckily this was the case in these three examples.

What different strengths did different people bring to the team?

Abhishek Das: I think different people bring different aspects of reasoning to explain the obtained results and which help us to understand the chemistry more as a team.

Marcel Swart: I think this team has been very successful because of the extensive expertise in oxidation chemistry, both from a synthesis/catalysis point of view (Minnesota), as spectroscopic characterisation (Carnegie Mellon) and computational studies (Carnegie Mellon, Girona).

Why is this work so important and exciting?

Bittu Chandra: In particular, our work that the oxygen atom transfer reactivity of a nonheme FeIV=O unit can be so significantly enhanced by a simple flip in its orientation relative to its macrocyclic tetraamine host is truly remarkable and suggests that there is much more that can be learned for catalyst design by paying attention to the effect of ligand topology on the iron active site.

Abhishek Das: This work provides useful understanding on how to design the primary as well as second coordination sphere to prepare synthetic model systems to replicate the efficiency of the enzymatic systems.

Yisong Guo: It has long been recognized that the reactivity of high-valent iron complexes, such as oxoiron(IV) complexes, is crucially influenced by the electronic properties of the oxoiron(IV) moiety and its primary coordination sphere in synthetic model complexes, however, the role of secondary coordination sphere on the chemical reactivity of the complexes has not been fully demonstrated. Our current work provides an excellent systematic study on this important aspect, thus elucidating new design principles to achieve high reactivity in oxoiron(IV) synthetic complexes.

Where do you see the biggest impact of this technology/research being?

Mehmet Jahja: This is the point of view of an apprentice molecular chemist but to me, one of the biggest impact of this research might be that these systems can be part of the synthetic chemist鈥檚 toolbox for efficient oxidation reactions.

Marcel Swart: Providing knowledge of the inner working of high-valent metal-oxo compounds, which serve as model system for metalloenzymes. I.e. through bioinspired chemistry in homogeneous catalysis we (can) learn more about enzymatic catalysis. This in turn can lead to new ideas and advances in homogeneous catalysis.

How will this work be used in real life applications?

Jin Xiong: The ultimate outcome of this work may promote sustainability by reducing the cost of chemical or biological syntheses through more efficient C-H activation methodologies, which lower material and energy consumption. In particular, it could help decrease the cost of developing and producing medications, as well as other high-value chemical products.

Yisong Guo: C-H functionalisation is one of the key topics in organic synthesis, to design cost effective catalysts that can perform efficient C-H activation on inert C-H bonds is one of the holy grail of organic synthesis and catalysis. Oxoiron(IV) complexes are known for their ability to activate inert C-H bonds. Our work provides additional design principles to achieve high-reactivity oxoiron(IV) complexes, which could be used to design oxoiron(IV)-based catalysts for more efficient C-H functionalisation.

How do you see this work developing over the next few years, and what is next for this technology/research?

Abhishek Das: As various model studies provide useful mechanistic information about the oxidation reactions of the high valent iron(IV)-oxo complexes, next challenge will be to utilise the synthetic systems practically to various useful organic transformations replicating the enzymatic efficiency.

Marcel Swart: Nowadays the design of new ligands is still based mostly on experimental work (synthesis) first. In the last couple of years, computational methods are catching up to such extent that within five years the order will be reversed. First a computational study will be done, and only if successful will the experimental part be tried. At least this is my prediction, and I hope to be able to contribute to this switch.

What inspires or motivates your team?

Marcel Swart: The inspiration often comes from Nature, which has devised metalloenzymes with such efficiency and selectivity that is difficult to match by homogeneous catalysts. For instance, the soluble methane monooxygenase is such an enzyme, which is one of the few that is able to activate the inert methane molecule and transform it into methanol.

What is the importance of collaboration in the chemical sciences?

Jin Xiong: Collaboration is often essential in the chemical sciences today. Although we appreciate the pioneers who push the frontiers of the chemical sciences significantly by themselves, the landscape of modern chemical research has changed dramatically due to the continual expansion of knowledge. Unlike in the past, advancing the frontiers of chemical sciences today often demands diverse expertise and multidisciplinary backgrounds.

While it is still possible for a single scientist to possess expertise across multiple disciplines, the time required is often extensive. From the perspective of societal efficiency, collaboration is indispensable for accelerating scientific advancement. This has been clearly demonstrated in our own team, which consists of excellent synthetic chemists, theoretical chemists and bioinorganic spectroscopists. Our collaboration significantly boosted our research by providing comprehensive approaches.

Abhishek Das: To get more clearer understanding about any scientific question, there are requirements of various spectroscopic techniques and experimental modifications. Along with the experimental part, the theoretical studies help to provide support to the experimental findings and can unveil new avenues. So active collaboration can bring various people with different expertise to come together to answer a broader question.

Mehmet Jahja: Chemical sciences are so vast that collaborations are a necessity. Each researcher has a specialty, and each specialty is a cornerstone of ambitious projects such as this one.

Marcel Swart: Each research team has its own expertise and equipment. Instead of attempting to replicate this, it is often better to specialise in a specific technique, with the corresponding equipment. That makes it easier to collaborate, especially if one participates e.g. in a COST Action (such as ECOSTBio, 2014-2018).

What does good research culture look like or mean to you?

Jin Xiong: I believe one of the most important factors contributing to a good research culture is openness and collaboration. As the knowledge continues to expand, it often requires multidisciplinary research to push the scientific frontiers forward. In this context, openness and collaboration have become more and more important. Effective communication improves research efficiency, and collaboration accelerates the expansion of our knowledge.

In addition, proper mentorship and training are also critical, as they help bring in new people and keep the scientific community moving forward. As a young researcher, I am especially grateful to Alex, Marcel and Larry for their guidance during this project. They not only supported me in this work but also played important roles in promoting my career.

Mehmet Jahja: Competent people respecting each other and sharing their knowledge to make progress in science.

Marcel Swart: Open-minded, diverse, flexible and supportive. This is difficult to find. Much of this can be achieved through trust, from both ends, and fairness. I.e. trusting others to do what they think is best, and giving them the space to develop their own research lines without interference or trying to impose oneself. Within this team there is this trust, from which the results have benefited.

How can scientists try to improve the environmental sustainability of research? Can you give us any examples from your own experience or context?

Marcel Swart: That is difficult. In principle, calculations are 鈥渃leaner鈥� for the environment because no chemicals are used, however, the electricity needed has an environmental cost as well. And in the end, the computational predictions need to be validated by experiments, so there is no escaping that.

Yisong Guo: Designing more efficient catalysts for C-H functionalisation could reduce the use of chemicals and solvents in organic synthesis, thus reducing environmental impact and improving sustainability. Our work elucidates new principles for designing oxoiron(IV) complexes that could exhibit excellent C-H activation reactivity, which could lead to generate more efficient C-H activation catalysts and ultimately provide positive impact to environmental sustainability.

What advice would you give to a young person considering a career in the chemical sciences?

Mehmet Jahja: In chemistry, there is room for any profile. Whether you like doing math, physics, biology or synthesis, you will always find a topic that will suit your preferences.

Marcel Swart: Go for it! Based on my experience as coordinator of the ECOSTBio COST Action (2014-18), I鈥檝e noticed that in principle chemists are quite open-minded, willing to listen to other opinions, and change their mind if new data show these to be correct. Moreover, the research groups in chemistry are in general very supportive of young students, helping them to get good quality education and willing to collaborate on a variety of topics. Even though the number of academic positions is obviously limited, a successful education in chemistry prepares one for industry.