Boron and beyond: celebrating Todd B. Marder's contributions to chemistry

Prof. Dr Dr h.c. Todd B. Marder is a world leader in a diverse range of ground-breaking chemistry. His work is characterized by attention to detail, and the fact that his fundamental studies of organometallic and main group systems lead to applications, developed by his own group and many others, in homogeneous catalysis, materials chemistry, and the synthesis of biologically active and bioimaging compounds. We believed that the New Journal of Chemistry is the perfect venue to highlight his diverse research program. We are most grateful to everyone that contributed to this issue and highlighted the remarkable impact Prof. Marder's research has made in science.

Following his BSc (MIT) and PhD (UCLA), Prof. Marder was a postdoctoral fellow at Bristol University (UK) and then a Visiting Research Scientist at DuPont Central Research and Development (USA) before taking up a faculty position at the University of Waterloo (Canada) where he rapidly rose through the ranks to Full Professor. In 1997, he accepted the Chair of Inorganic Chemistry at Durham University (UK). In 2012, he moved to the Julius-Maximilians-Universität Würzburg (Germany) as Chair I of Inorganic Chemistry.

He has held visiting, honorary, or similar professorships in the UK, France, Canada, Hong Kong, Japan, India, and China, and was the 2014 David Craig Visiting Professor at Australian National University. He currently holds an Honorary Professorship at Durham University (UK), an Adjunct Professorship at the Hong Kong University of Science and Technology, a Guest Professorship at Shandong University (China), a Visiting Professorship at Northeast Normal University (China), and a Consultant Professorship at Northwestern Polytechnical University (China). As of February 1, 2021, he has published over 385 papers, which have been cited around 25 000 times (h-index = 88) and has filed several patents. He has given over 415 invited lectures worldwide.

His major awards include the Rutherford Memorial Medal for Chemistry (Royal Society of Canada, 1995 – leading chemist under 40 in Canada), the Royal Society of Chemistry (UK) Awards in Main Group Element Chemistry (2008) and in Organometallic Chemistry (2015), a Japan Society for the Promotion of Science JSPS Invitation Fellowship (2010), a Royal Society (UK) Wolfson Research Merit Award (2010), and an Alexander von Humboldt Foundation (senior) Research Award (2010) which subsequently led to his permanent move to Würzburg in 2012. He was elected as a Fellow of the Royal Society of Chemistry (UK) in 1997 and to the Bayerische Akademie der Wissenschaften (the Bavarian Academy of Science) in 2015, Fellow of the American Association for the Advancement of Science (AAAS) in 2018, and Fellow of the European Academy of Sciences (EurASc) in 2019. He also received an honorary doctorate from the University of Rennes 1 (France) in April 2018 and has served on the editorial boards of Organometallics, Inorg. Chem., J. Organometal. Chem., Applied Organometal. Chem., Inorg. Chim. Acta, Can. J. Chem., Crystal Eng., and Chin. J. Chem.

Prof. Marder has carried out internationally leading independent research for over 35 years, including fundamental studies into the synthesis, structure, bonding, and photophysical properties of organometallic and organoboron compounds, as well as applications in homogeneous catalysis and materials chemistry. He was one of the first to develop a catalyst for the intermolecular hydroacylation of alkenes and transition metal catalysts for the cyclization of alkynoic acids to enol lactones. He has developed novel routes to metal acetylide complexes and polymers via C–H activation and examined their linear and nonlinear optical properties. He discovered the quantitative formation of novel luminescent rhodacyclopentadienes which are highly unusual organometallic luminophores in that they fluoresce rather than phosphoresce, exhibiting quantum yields as high as 70%. Most recently, he has developed novel phosphorescent rhodacycles with exceptionally long-lived triplet excited states in solution at room temperature and is currently exploiting these for applications in visible-light induced photocatalysis.¹

For over 30 years, he has done pioneering work on the linear and nonlinear optical properties of 3-coordinate organoboron compounds,^2,3 inspiring many groups worldwide to explore the optical and electronic properties of organoboron compounds, and he has published 3 leading reviews in this area.² Very recently, following up on his fundamental studies, he has developed novel boron-based chromophores for the 1- and 2-photon excited fluorescence imaging of organelles in live cells⁴ and for sensing DNA, RNA, and proteins.⁵

Prof. Marder is probably best known for his pioneering studies of transition metal boryl complexes and their applications in metal-catalyzed borylations, including hydroboration, diboration, and the first example of what is now known as β-borylation. He has made remarkable developments in the efficient one-pot, multi-step, single-solvent processes for arene C–H borylation followed by Suzuki–Miyaura or conjugate addition reactions. He is also responsible for demonstrating the first catalytic borylation of benzylic C–H bonds. Subsequent work has investigated detailed studies of the steric and electronic effects on arene C–H borylation selectivity, the discovery of inexpensive and highly active Cu and Zn catalysts for the borylation of aryl and even primary, secondary and tertiary alkyl halides. Recent studies have focused on using Ni catalysts for the synthesis of multifluoroarenes as building blocks for synthesis via C–F borylation.

Developing methodologies for the catalyzed arene and alkene C–H borylations and Pd-catalyzed cross-couplings, he discovered the rapid efficient syntheses of stable retinoids (analogues of retinoic acid) which trigger stem cell differentiation to form neurons. From this starting discovery, Prof. Marder and his research team have also developed luminescent retinoids (several patents filed, lead compounds commercialized).

He has developed a rapid and efficient synthesis of 2- and 2,7-substituted pyrene derivatives directly from pyrene via metal-catalysed C–H borylation, revolutionising access to this important class of compounds and chromophores and has been exploiting such derivatives⁶ for numerous applications via many international collaborations.

He has also done pioneering studies on diboron(4) reagents⁷ and their Lewis base adducts⁸ and, in collaboration with Prof. Nicholas C. Norman, is responsible for generating bis(neopentaneglycolato)diboron (B₂neop₂), now a widely used reagent produced in ton quantities and distributed commercially by companies in North America, Europe, Asia and Australia, that is used by researchers all over the world. He has also recently reported a reversible boron–carbon oxidative addition to a carbene carbon atom.⁹

His work with fluoroarene–arene interactions and their applications in crystal engineering and liquid crystals has already afforded over 25 articles. Most recently, along with his associate, Dr Alexandra Friedrich, and a multinational team, he has reported the pressure-induced polymerization of polycyclic arene–perfluoroarene cocrystals, including high pressure single-crystal X-ray diffraction studies.¹⁰

His research has been supported by both multinational and small companies such as DuPont, Imperial Oil, ICI Synetix, Johnson Matthey Catalysts, GlaxoSmithKline, Syngenta, ReInnervate Ltd, High Force Research Ltd, and numerous funding agencies in the US, Canada, the UK, and Germany. Since moving to Würzburg in 2012, he established a research group of ca. 40 co-workers, including numerous Humboldt Fellows, overseas funded PhD students, and visiting researchers.

He has always been involved in international activities and has run truly international research groups at universities in 3 countries. He was the International Ambassador for the Department of Chemistry at Durham University (UK) and is a member of the university level Internationalization Commission of the Julius-Maximilians-Universität Würzburg. He has delivered lectures on International Cooperation and Collaboration in Chemistry in the UK, India, South Korea, and China. At Durham he was the leader of the Durham University (UK) – University of Rennes 1 (France) CNRS PICS (International Program for Scientific Cooperation) and the subsequent CNRS LEA (European Associated Laboratory) before moving to Würzburg. He has organized numerous symposia and conferences around the world and has been a member of both the International Scientific Committee of the IMEBORON Conference series (the international conferences on boron chemistry) and the Euroboron Conference series (the European conferences on boron chemistry) for many years.

One of the biggest impacts Prof. Marder has made in his career (so far) has involved the training of highly qualified personnel and giving so many young scientists, from all around the world, opportunities to explore the wonders of chemistry. During his illustrious career, he now has around 35 of his former students and co-workers holding academic appointments around the world (US, Canada, UK, Germany, France, Spain, Nigeria, Saudi Arabia, Thailand, Malaysia, India, Singapore, Japan, Hong Kong and mainland China), and countless others in industry, the health sciences professions and in education. His interest and love of chemistry continues to inspire many young scientists, and so many have benefitted from his positive attitude in exploring the wonders and marvels of science. Prof. Marder has spent his career disseminating his research results all over the world and discussing his travels throughout the periodic table. One can only wonder where his next journey in chemistry will take him!

References

1. Y.-M. Tian, X.-N. Guo, M. Kuntze-Fechner, I. Krummenacher, H. Braunschweig, U. Radius, A. Steffen and T. B. Marder, Selective photocatalytic C–F borylation of polyfluoroarenes by Rh/Ni dual catalysis providing valuable fluorinated arylboronate esters, J. Am. Chem. Soc., 2018, 140, 17612–17623.
2. L. Ji, S. Griesbeck and T. B. Marder, Recent developments in and perspectives on three-coordinate boron materials: a bright future, Chem. Sci., 2017, 8, 846–863.
3. Z. Wu, J. Nitsch, J. Schuster, A. Friedrich, K. Edkins, M. Loebnitz, F. Dinkelbach, V. Stepanenko, F. Würthner, C. M. Marian, L. Ji and T. B. Marder, Persistent room temperature phosphorescence from triarylboranes, Angew. Chem., Int. Ed., 2020, 59, 17137–17144.
4. S. Griesbeck, E. Michail, C. Wang, H. Ogasawara, S. Lorenzen, L. Gerstner, T. Zhang, J. Nitsch, Y. Sato, R. Bertermann, M. Taki, C. Lambert, S. Yamaguchi and T. B. Marder, Tuning the π-bridge of quadrupolar triarylborane chromophores for one- and two-photon excited fluorescence imaging of lysosomes in live cells, Chem. Sci., 2019, 10, 5405–5422.
5. Ž. Ban, S. Griesbeck, S. Tomić, J. Nitsch, T. B. Marder and I. Piantanida, A quadrupolar bis-triarylborane chromophore as a fluorimetric and chirooptic probe for simultaneous and selective sensing of DNA, RNA and proteins, Chem. – Eur. J., 2020, 26, 2195–2203.
6. J. Merz, J. Fink, A. Friedrich, I. Krummenacher, H. H. Al Mamari, S. Lorenzen, M. Hähnel, A. Eichhorn, M. Moos, M. Holzapfel, H. Braunschweig, C. Lambert, A. Steffen, L. Ji and T. B. Marder, Pyrene MO shuffle – controlling excited state and redox properties by changing the nature of the frontier orbitals, Chem. – Eur. J., 2017, 23, 13164–13180.
7. E. C. Neeve, S. J. Geier, I. A. I. Mkhalid, S. A. Westcott and T. B. Marder, Diboron(4) compounds: from structural curiosity to synthetic workhorse, Chem. Rev., 2016, 116, 9091–9161.
8. R. D. Dewhurst, E. C. Neeve, H. Braunschweig and T. B. Marder, sp²–sp³ diboranes: astounding structural variability and mild sources of nucleophilic boron for organic synthesis, Chem. Commun., 2015, 51, 9594–9607.
9. A. F. Eichhorn, S. Fuchs, M. Flock, T. B. Marder and U. Radius, Reversible oxidative addition at carbon, Angew. Chem., Int. Ed., 2017, 56, 10209–10213.
10. A. Friedrich, I. E. Collings, K. F. Dziubek, S. Fanetti, K. Radacki, J. Ruiz-Fuertes, J. Pellicer-Porres, M. Hanfland, D. Sieh, R. Bini, S. J. Clark and T. B. Marder, Pressure-induced polymerization of polycyclic arene-perfluoroarene cocrystals: single crystal X-ray diffraction studies, reaction kinetics, and design of columnar hydrofluorocarbons, J. Am. Chem. Soc., 2020, 142, 18907–18923.

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