The Constants of Transformations

Paul Barron

Almost sixty years ago, David Edmonds met his friend for a coffee in the University of Birmingham  Students’ Union bar. This friend suggested that Edmonds, who had unsuccessfully applied to read  physics, should speak to the admissions tutor at the Metallurgy Department[1]. This chance exchange  set in motion a career which began with his doctoral studies, in which he researched zirconium-based  materials that were used to clad fuel rods in early nuclear fission reactors[2], and would eventually  leave an enormous mark on the world of metallurgy through his many discoveries on the phase  transformations of steels and other metals[3]. However, his impact, like the materials he worked with, has endured and adapted in no small part due to the work of his former students. 

Amongst them is Prof Sir Harry Bhadeshia, now also an internationally renowned figure in  metallurgical academia. Like his supervisor, Bhadeshia made many contributions to the understanding  of phase changes in steels[4]. One of his myriad discoveries was elucidating some transformation behaviour in nuclear reactor pressure vessels[5], a finding that will no doubt improve the lifetime of  both current and future reactors. This is just one example of how Bhadeshia’s work was driven by a  desire to improve important technologies using metallurgy[6]. Bhadeshia went on to supervise  doctoral students at the University of Cambridge (where I had the good fortune of being lectured by  him!), including Dr Ed Pickering, now my supervisor at the University of Manchester and already a  well-established metallurgist despite his relative youth. 

Pickering’s doctoral studies focussed on the changes that take place inside the massive ingots that are  forged into the same nuclear reactor pressure vessels that were a focus of his supervisor’s work[7].  After completing his PhD, Pickering’s academic work branched out into a more general study of phases  in other metals such as high-entropy alloys, a relatively new class of material that aims to exploit the  often-exceptional properties produced when many elements are mixed in roughly equal  proportions[8]. High-entropy alloys may offer a new direction for materials research in the field of  nuclear fusion. This forms the basis of my doctoral studies. 

Like my predecessors, I study how metals may change in the harsh environments inside nuclear  reactors. Although the materials and nuclear technology have changed, the motivations have not.  Understanding phase transformations in metals is key to improving them and the technologies that  rely on them, be it nuclear fission or fusion, or something else entirely. I believe it is this shared desire  to improve the world through better materials that unites the four of us. 

When searching for similarities in our research career, it can be easy to get carried away by grand  notions of a common goal, when it is often the small events in life that can be so important in  motivating someone. For instance, Bhadeshia stated in an interview that visiting his father’s battery  shop was what first piqued his interest in the scientific world[6]. This struck me as very similar to the  way trips to my grandfather’s machining workshop would kindle my curiosity about metals and how they could be hard yet malleable. Another curious commonality was Edmonds’ decision to pursue  metallurgy instead of physics, which was echoed by my own choice of specialising in materials science  after finding physics too difficult during undergraduate. All these motivating factors, grand and small,  have resulted in immense contributions to society by three distinguished academics. I can only hope  that my own career has even a fraction of their impact!

References 

[1] D. V. Edmonds, Personal communication. Nov 2020. 

[2] D. V. Edmonds and C. J. Beevers, “Some observations on discontinuous yielding in Zircaloy-2,” Journal of Nuclear Materials, vol. 28, no. 3. North-Holland, pp. 345–348, 01-Dec-1968. 

[3] J. G. Speer and H. K. D. H. Bhadeshia, “A tribute to Professor David V. Edmonds on the eve of  his retirement,” Mater. Sci. Technol. Conf. Exhib. 2009, MS T’09, vol. 3, pp. 1575–1590, 2009. 

[4] H. K. D. H. Bhadeshia and D. V. Edmonds, “The mechanism of bainite formation in steels,” Acta Metall., vol. 28, no. 9, pp. 1265–1273, Sep. 1980. 

[5] H. Pous-Romero, I. Lonardelli, D. Cogswell, and H. K. D. H. Bhadeshia, “Austenite grain growth  in a nuclear pressure vessel steel,” Mater. Sci. Eng. A, vol. 567, pp. 72–79, Apr. 2013. 

[6] British Library, “Harry Bhadeshia: life as a scientist,” Voices of Science, 2013. [Online].  Available: https://www.bl.uk/voices-of-science/interviewees/harry-bhadeshia/video/harry bhadeshia-life-as-a-scientist. 

[7] E. J. Pickering, “Macrosegregation in steel ingots,” University of Cambridge, 2014. 

[8] E. J. Pickering and N. G. Jones, “High-entropy alloys: a critical assessment of their founding  principles and future prospects,” Int. Mater. Rev., vol. 6608, no. May, pp. 1–20, 2016.

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2020 Ereztech BridgeForward™ Award Essay

Olja Simoska

Genealogies of research training are significant when considering scientific influences. Every  professor who trains a graduate student was once a student researching with another professor, creating a scientific linage. This academic history provides a vital perspective of the transmission  of ideas and their transmutation to one’s research. My scientific family tree begins with my  academic ‘father’ and outstanding Ph.D. mentor, Keith J. Stevenson. Stevenson completed his  graduate studies at University of Utah under the mentorship of Henry S. White, who obtained his  Ph.D. at University of Texas with Allen J. Bard. In addition to my interactions with my Ph.D.  mentor, I have had the opportunity to meet both my academic ‘grandfather’ and ‘great grandfather,’ who are professors at my post-doc and Ph.D. home institutions, respectively.  Recognized as the ‘father of modern electrochemistry,’ Bard has made immense  contributions in the field (e.g., electrochemiluminescence, development of scanning  electrochemical microscope, authoring the principal electrochemistry textbook). By applying  electrochemical methodologies to study chemical problems, Bard deepened the fundamental  understanding of electron-transfer reactions and fostered the development of electroanalytical  techniques/instrumentations. Through merging experimental and theoretical aspects of  fundamental electrochemistry, White has devoted his research to studying electrochemistry in  nanoscale domains, which is the driving science behind batteries, molecular electronics, and  chemical sensors. White’s major contributions are studies of electrochemically generated  nanobubbles and the creation of nanopore electrodes. My academic ‘father’ Stevenson has been  extremely innovative/unique in his approach blending fundamental electrochemistry with  materials science. His research mainly aims at elucidating chemistry at solid-liquid interfaces  critical to emerging energy storage and energy conversion technologies. Stevenson expands the  understanding of how materials behave, allowing him to apply existing materials to various  technologies and to design novel, improved materials. With Stevenson’s tremendous creativity in materials, my Ph.D. work focused on a distinctive electrode material combination to develop a  nanometer-size electrode array platform. The latter portion of my Ph.D., extending to a different  area, utilized this electrochemical platform for the real-time monitoring of cellular redox  metabolites, providing a substantial quantitative basis for understanding microbial infections and  virulence mechanisms in complex biological systems.  

Exploring my mentorship lineage and its history points to overlaps in research  fundamentals and electrochemistry concepts. However, the questions motivating the research  interests change through generations due to the interdisciplinary nature of electrochemistry. My academic forebears might have been decades away from practical applications as their research established the foundations of fundamental electrochemistry. From my perspective, thoughts of  real-world applications impacted the research directions of each generation. The current challenges in developing electrochemical technologies for practical uses (e.g., sensors, fuel cells, batteries)  still depend on these principal concepts, which infiltrate through the traditional chemistry  disciplines and will carry forward onto the next generations.  

This is not just academic history, but rather a story about leading electrochemists and  evidence of inspiring research. My preceding generations create a lineage of scientists who have  deepened our understanding of the physical world. Isaac Newton once said, “If I have seen a little  further, it is by standing on the shoulders of giants,” which applies here as these are generations of  valuable advisors. I know from firsthand experience that Stevenson undoubtedly is an outstanding mentor, and in my path forward, I will emulate him. During my Ph.D., he has done a stellar job  with long-distance mentorship. This cultural mentorship aspect is unprecedented, differentiating  Stevenson from my academic grandfathers. Stevenson builds not only research programs but also  the students who will keep carrying science forward – science that truly matters in the lives of  everyday individuals. By sharing the joy of what we do with younger generations of  electrochemists, we create a legacy that matters most.

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BridgeForward Essay

Jonathan Dabbs

At the University of Virginia, a black-and-white photo of Dr. Henry Taube hangs in Dr. W. Dean Harman’s lab. Harman repeatedly emphasizes that this photo is both a tribute to his late advisor and an acknowledgement that the ongoing research conducted in the Harman lab rests upon the shoulders of the work carried out by Taube.

The primary research interest of the Harman Lab is accessing novel chemical space and synthesizing topologically-complex small-molecules that are rich in stereocenters. This is done by the dihapto (η²) coordination of various aromatic compounds stoichiometrically to a π-basic transition metal complex.¹ Once η² bound, the aromatic molecule is then activated for highly regio- and stereoselective tandem electrophilic/nucleophilic additions across the remaining uncoordinated olefins. Libraries of these highly functionalized small molecules are then assembled after oxidatively liberating them from the metal.

The keystone of this research is the η² bond, which consists of a σ-donor and π-acceptor qualities of aromatic ligands. The π* orbital of the aromatic ligand accepts π-electron density backbonded from the π-symmetric t2g orbitals of the d6 W(0) metal center thus forming a metallacyclopropane-like structure between the metal and the coordinated olefin.

The first reported instance of an aromatic molecule η²-bound to a metal complex was reported by both Harman and Taube.² At the time, Taube’s research focus was on electron transfer (ET) between transition metals, work he was famously awarded the Nobel Prize for in 1983.³ After investigating ET between pentaamine-Co3+ complexes bridged to Cr2+ and proposing concepts such as “Inner-Sphere” and “Outer-Sphere” mechanisms,4,5  Taube began examining ET with pentaamine-Ru3+ and pentaamine-Os3+ complexes.6–8  These complexes, which were chosen due to their π-symmetric acceptor orbitals, displayed acute backbonding. The pentaamine-Os complex backbonds so effectively that it was serendipitously discovered to dearomatize benzene and other aromatic molecules through an η² bond.

Taube shifted his research focus to investigating ET between inorganic complexes after preparing to teach a course by reading about transition metal cations at the University of Chicago. Before this, he examined oxidation-reduction reactions with a strong focus on reactive oxygen species (ozone, peroxides, oxygen radicals, etc.).9–11 This body of work stemmed from his doctoral work at the University of California at Berkeley with his advisor, Dr. William C. Bray.

The two Canadian chemists had an excellent rapport. After winning the 1985 ACS Priestly Medal, Taube dedicated his speech to his late advisor in which he hailed Bray as the “herald of inorganic reaction kinetics.”12 In 1940, Taube and Bray published a noteworthy paper examining the effects of halogen ions on the rates of ozone and peroxide reactions, which likely jumpstarted Taube’s initial research interests. 13

While conducting impactful research on main group reaction kinetics and catalysis,15–17 Bray also transformed chemical education with his textbook A Course in General Chemistry and a strong belief in the importance of an active-learning based laboratory course. He recognized that research and teaching are both critical not only students but also professors in advancing chemical understanding. Taube, who stated this was Bray’s greatest contribution to the field, himself greatly benefitted from teaching a course that led to his Nobel-winning research. Keeping with this idea, Harman continues to teach general chemistry at Virginia where has won numerous faculty teaching awards.

The careers of Harman, Taube, and Bray demonstrate the power of an advanced understanding of electron movement. Despite having various research interests and applications ranging from developing druglike small-molecule libraries or inventing a catalyst for oxidizing carbon monoxide during World War I (as Bray did), the common thread is a firm grasp of the behavior of redox reactions in main group and transition metals.

References

(1) Liebov, B. K.; Harman, W. D. Group 6 Dihapto-Coordinate Dearomatization Agents for Organic Synthesis. Chemical Reviews. American Chemical Society November 22, 2017, pp 13721–13755. https://doi.org/10.1021/acs.chemrev.7b00480.

(2) Harman, W. D.; Taube, H. Reactivity of Pentaannnineosmium(II) with Benzene. J. Am. Chem. Soc. 1987, 109 (6), 1883–1885. https://doi.org/10.1021/ja00240a061.

(3) Henry Taube – Nobel Lecture https://www.nobelprize.org/prizes/chemistry/1983/taube/lecture/ (accessed Nov 29, 2020).

(4) Taube, H.; Myers, H. Evidence for a Bridged Activated Complex for Electron Transfer Reactions. J. Am. Chem. Soc. 1954, 76 (8), 2103–2111. https://doi.org/10.1021/ja01637a020.

(5) Taube, H.; Myers, H.; Rich, R. L. Observations on the Mechanism of Electron Transfer in Solution. Journal of the American Chemical Society. American Chemical Society August 1, 1953, pp 4118–4119. https://doi.org/10.1021/ja01112a546.

(6) Endicott, J. F.; Taube, H. Studies on Oxidation-Reduction Reactions of Ruthenium Ammines. Inorg. Chem. 1965, 4 (4), 437–445. https://doi.org/10.1021/ic50026a001.

(7) Stritar, J. A.; Taube, H. Electron-Transfer Reactions of Ruthenium(III) Pentaammines with Chromium(II), Vanadium(II), and Europium(II). Inorg. Chem. 1969, 8 (11), 2281–2292. https://doi.org/10.1021/ic50081a013.

(8) Magnuson, R. H.; Taube, H. Synthesis and Properties of Osmium(II) and Osmium(III) Ammine Complexes of Aromatic Nitrogen Heterocyclics. J. Am. Chem. Soc. 1975, 97 (18), 5129–5136. https://doi.org/10.1021/ja00851a018.

(9) Espenson, J. H.; Taube, H. Tracer Experiments with Ozone as Oxidizing Agent in Aqueous Solution. Inorg. Chem. 1965, 4 (5), 704–709. https://doi.org/10.1021/ic50027a023.

(10) Halperin, J.; Taube, H. The Transfer of Oxygen Atoms in Oxidation-Reduction Reactions. IV. The Reaction of Hydrogen Peroxide with Sulfite and Thiosulfate, and of Oxygen, Manganese Dioxide and of Permanganate with Sulfite. J. Am. Chem. Soc. 1952, 74 (2), 380–382. https://doi.org/10.1021/ja01122a027.

(11) Forchheimer, O. L.; Taube, H. Evidence for the Exchange of Hydroxyl Radical with Water. Journal of the American Chemical Society. UTC July 1, 1952, pp 3705–3706. https://doi.org/10.1021/ja01134a518.

(12) Taube, H. William C. Bray—Teacher and Herald of Inorganic Reaction Kinetics. Chem. Eng. News 1985, 63 (18), 40–45. https://doi.org/10.1021/cen-v063n018.p040.

(13) Taube, H.; Bray, W. C. Chain Reactions in Aqueous Solutions Containing Ozone, Hydrogen Peroxide and Acid. J. Am. Chem. Soc. 1940, 62 (12), 3357–3373. https://doi.org/10.1021/ja01869a027.

(14) Cervellati, R.; Greco, E. Periodic Reactions: The Early Works of William C. Bray and Alfred J. Lotka. J. Chem. Educ. 2017, 94 (2), 195–201. https://doi.org/10.1021/acs.jchemed.6b00342.

(15) Bray, W. C. A Periodic Reaction in Homogeneous Solution and Its Relation to Catalysis. J. Am. Chem. Soc. 1921, 43 (6), 1262–1267. https://doi.org/10.1021/ja01439a007.

(16) Hershey, A. V; Bray, W. C.; 58, V.; Brav, W. C. Kinetic and Equilibrium Measurements of the Reaction 2Fe+++ + 2I- = 2Fe++ + I2 . J. Am. Chem. Soc 1936, 58, 1760–1772.

(17) Bray, W. C.; Livingston, R. S. The Catalytic Decomposition of Hydrogen Peroxide in a Bromine-Bromide Solution, and a Study of the Steady State. J. Am. Chem. Soc 1923, 45

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BridgeForward Essay

Eric Kazyak

In 1675, Isaac Newton famously said, “If I have seen further it is by standing on the shoulders of Giants.” This now proverbial statement remains the foundation of the research process, enabling mentors to guide their students further than they have gone themselves. This is true not only of the knowledge and facts passed down (and built upon), but perhaps more importantly of the perspectives and ways of thinking about problems that students learn from their advisors. My own advisor, Dr. Neil Dasgupta, stressed this idea early on; our advisors, and in turn their advisors, shape not only what we know, but how we think. Neil’s interdisciplinary background in mechanical engineering, materials science, and chemistry has had dramatic impacts on the directions that our work has taken. 

Throughout history, and certainly in the modern era, many of the greatest breakthroughs have come about by approaching an existing problem from a new perspective.1 As the scientific community has exploded in size over the past two centuries, interdisciplinary work and thinking have become more vital. Knowledge and expertise have become more and more specialized and fragmented. In a way, these silos of knowledge could be described as tall but skinny towers of those standing on the “giants” immediately beneath them, while other fields often work on similar problems in their own silos. Thus, the power of the interdisciplinary approach stems from the ability to connect the accomplishments from disparate fields, add your own contribution/perspective, and integrate everything into a cohesive result that advances the state of knowledge. This also highlights the value of diversity in cultural and academic backgrounds, with diverse opinions enriching discussions and leading to more fruitful research.

While I have not had the privilege of meeting my advisor’s advisor, I was fortunate to have dinner several years ago with my academic great-great-grandfather (4th generation), Dr. Nathan Lewis. It was immediately evident that many of his perspectives and thought-processes had endured through the generations. He told a story about his favorite experiment, which involved an experimental setup utilizing a paper towel roll for an integral component. He emphasized that the most impactful experiments are not necessarily the ones which are the prettiest, or the most expensive, but those that approach important problems in unique and creative ways. I had already internalized this philosophy without realizing that it had been passed down from my forefathers. All this to say that even in cases where we don’t realize it, the lessons and approaches learned generations earlier play a central role in our daily research endeavors. 

My own work on next-generation batteries has many common threads with Prof. Lewis’ work on artificial photosynthesis. In both cases, it is critical to approach problems with a systems-level understanding, while simultaneously studying interfacial phenomena across length scales from centimeters to nanometers. For instance, both lithium-metal batteries and water splitting devices suffer from poor long-term stability due to undesirable interfacial reactions.2,3 In both cases, by carefully tuning the ionic/electronic transport properties of atomic layer deposition coatings, enhanced stability was enabled. The underlying theme in these works is that mechanistic understanding leads to the ability to rationally design solutions to real-world problems. In this sense, all of my academic forefathers have similar approaches to research. While knowledge for the sake of knowledge has value, they prefer to focus on having consequential impact on society by advancing the understanding and performance of practical systems. In today’s fast-moving and chaotic society, it is more important than ever before to maintain a sense of appreciation and understanding of the giants that came before us, and on whose shoulders we stand.

References

(1) Reich, Y.; Shai, O. The Interdisciplinary Engineering Knowledge Genome. Res. Eng. Des. 2012, 23 (3), 251–264. https://doi.org/10.1007/s00163-012-0129-x.

(2) Shaner, M. R.; Hu, S.; Sun, K.; Lewis, N. S. Stabilization of Si Microwire Arrays for Solar-Driven H2O Oxidation to O2(g) in 1.0 M KOH(Aq) Using Conformal Coatings of Amorphous TiO2. Energy Environ. Sci. 2015, 8 (1), 203–207. https://doi.org/10.1039/c4ee03012e.

(3) Kazyak, E.; Chen, K. H.; Davis, A. L.; Yu, S.; Sanchez, A. J.; Lasso, J.; Bielinski, A. R.; Thompson, T.; Sakamoto, J.; Siegel, D. J.; Dasgupta, N. P. Atomic Layer Deposition and First Principles Modeling of Glassy Li3BO3-Li2CO3 Electrolytes for Solid-State Li Metal Batteries. J. Mater. Chem. A 2018, 6 (40), 19425–19437. https://doi.org/10.1039/c8ta08761j.

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BridgeForward Essay

Michael Foody

Organometallic synthesis is impossible to learn without the guided care of a mentor. It is the perseverant relationship between mentor and protégé that has sustained hundreds of years of organometallic progress. I learned organometallic synthesis from my advisor, Adam Hock, and upon reflection on my deeper academic legacy, I notice certain motifs and perspectives I have unknowingly adopted. Notably, a perspective on scientific progress that emphasizes applications – that while many compounds may be intellectually interesting, a scientist should not neglect the basic usefulness of organometallics. I also appreciate personal similarities in my academic lineage. From my great-grand-advisor John Osborn, to my grand-advisor Richard ‘Dick’ Schrock, to my advisor Adam Hock, and in myself there is a pervasive optimism and enthusiasm for this work we share.

John A. Osborn was born in Kent, Britain in the year before the Nazi siege of Britain, 1939. His graduate work was with Geoffrey Wilkinson, where he was among the first chemists to synthesize chlor(tris-triphenylphosphine)rhodium(I), otherwise known as Wilkinson’s catalyst. Osborn spent his career synthesizing compounds for catalytic transformations of olefins. His compound tris-(triphenylphosphine)rhodium carbonyl hydride is still used industrially today for hydroformylation reactions. Although he passed away in 2000 from brain cancer, pictures of him can be found on-line where throughout his life he never seemed to have lost his bright assertive eyes, framed by a tangle of disheveled hair and a thick gray beard.

Dick Schrock met his advisor in 1967 during Osborn’s first year as a faculty member and Dick’s first year as a student. Dick would write a memorial for his advisor 33 year later where he described that meeting: “John told me about transition metals, about catalysis, about the excitement of creating new compounds, and about creating them for a purpose.” Dick Schrock grew up in rural Indiana and was six years younger than his advisor. His enthusiasm for chemistry was apparent from his earliest days, going so far as to convert a household storage area into a chemistry lab at the age of 13. His enthusiasm was surely well received by his advisor. Later at DuPont, he discovered the first alkylidene-based compounds for high oxidation state metals. After moving to MIT, he would use the chemistry of metal alkylidenes to perform olefin metathesis reactions. This work would be awarded the 2005 Nobel Prize in Chemistry.

Adam was a second year student in the Schrock Group during the Nobel excitement. Adam in many ways is like Dick. From rural Pennsylvania, Adam developed his interest in synthetic chemistry at a very young age. Both he and his advisor have a good-natured charm that conceals a strong competitive spirit. Adam still speaks fondly of his relationship with Dick and the years he spent in the Schrock Group. Like Dick, I began my graduate work with a young assistant professor, and over the years Adam has taken his expertise in organometallic synthesis and applied it to atomic layer deposition (ALD). Adam has made a point of teaching his students to be synthetic chemists first and applying synthetic principles to other fields. Indeed, my thesis aspires to analyze ALD precursors and reaction chemistry from the perspective of an organometallic synthetic chemist. I could not have written my thesis without the pioneering work into organometallics done by John Osborn in the 1960’s. Without the optimistic sense of progress that was instilled into Dick, my own development as a synthetic chemist would not be possible. This is the essence of science: we use the fundamental relationship between student and teacher to pass the fruits of scientific inquiry to the next generation. And in this we make progress.

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