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April 8, 2002
Volume 80, Number 14
CENEAR 80 14 pp. 39-43
ISSN 0009-2347
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For more than 40 years, focus, concentration, and talent have been hallmarks of Allen J. Bard's quest to understand the molecular basis of electrochemistry




The hallways in the chemistry building at the University of Texas, Austin, are decorated with colorful posters depicting the latest research coming from the department's laboratories. The walls outside Allen J. Bard's office are a little different. Instead of describing his latest research, Bard displays a large map covered with flags that mark the whereabouts of his former students.




The display seems in keeping with this engagingly modest man. Bard, the Norman Hackerman-Welch Regents Professor of Chemistry at the university, is known for many things: He's an eminent electrochemist; recently retired editor of the Journal of the American Chemical Society, ACS's premier research journal; former president of the International Union of Pure & Applied Chemistry; former chair of the chemistry section of the National Academy of Sciences; and a mentor to generations of colleagues and students. Of all of those accomplishments, in his own estimation, his students are the most important.

"Whatever I've done as a scientist will be there for a while, but then fade away," Bard says. "The big names in science quickly become unknown. But through your students you maintain a presence in future generations, and they go on and on and on."

Teaching--in the classroom and by guiding student research--is clearly a pleasure for the 68-year-old Bard. He recently told a group of UT chemistry students, "I really enjoy interacting with students, watching them grasp new concepts, watching them get very good in the field from a very poor beginning. I think just working with young people is a lot of fun."

Bard has been working with young people at Texas for nearly 44 years. In the process, he's become one of the world's foremost electrochemists and a man widely known and respected throughout the profession. That respect is evident this week, as ACS awards him its highest honor, the Priestley Medal, given annually for distinguished service to chemistry.

Those who know his work don't expect Bard's scientific accomplishments to fade away anytime soon. "He's been the single most substantial influence on the electrochemical literature in the past 50 years," says former graduate student Larry R. Faulkner, now president of the University of Texas, Austin.

Fred C. Anson, professor emeritus of chemistry at California Institute of Technology, has known Bard since they were graduate students in the same research group at Harvard University in the 1950s. "He's always had an intense and very catholic inquisitiveness about all kinds of chemical topics," Anson says. "And he's always matched that with an enthusiasm for scientific research and a degree of focus, concentration, and industry that is really rare. He has managed to accomplish so much more than anybody else I can think of under the same circumstances."

"He's a scientist's scientist," says former Texas colleague Marye Anne Fox, now chancellor of North Carolina State University. "He really has done it all. He's a wonderful teacher. He's a superb and innovative researcher. He has been an incredible mentor to me throughout my career. From my earliest days as an assistant professor at Texas, he's helped me and been willing to be critical about my work. He's also had leadership positions in virtually every major chemical society."


EARLY BIRD Future JACS editor wrote a column for his junior high school newspaper.

BARD SEEMS uncomfortable with such praise. "In your life, you are either underappreciated or overappreciated," he noted recently. "When I was younger, I was completely underappreciated; now I'm sure I'm completely overappreciated!"

There was never much question that Bard would be a scientist. "From as early a time as I can remember, I liked science," he says. Born in New York City in 1933, he spent many hours as a young boy in the company of his older brother or sister at New York's American Museum of Natural History or the museum's Hayden Planetarium. "I liked doing experiments and collecting things, like leaves and bugs. Through grade school and junior high school, I always liked science classes best."

As a student at the Bronx High School of Science in the late 1940s, Bard, though good at chemistry, was more interested in biology. He enjoyed working with his sister-in-law, a botanist at Rutgers University, doing ecological studies. Yet he wasn't sure he wanted a career in biology. "I mistakenly felt in 1950 that biology was too much about classification," he recalls. "It seemed too routine. I like things that are more theoretical, more molecular. So I thought chemistry was a better place to go. Biology was changing, but I didn't know that. I didn't know about molecular biology. In retrospect, I don't know what would have happened if I had stayed with biology."

Bard's parents, both European immigrants, encouraged education and sent all of their children to college. Money was tight, and Bard attended the then-free City College of New York. It was a hard school to get into, he recalls, but once there, the faculty were devoted to the students and were very good at teaching fundamentals. There was no graduate program at the college at that time, so science faculty did little research. As Bard was to discover when he entered graduate school at Harvard University in 1955, that focus on undergraduate teaching left him a bit behind some of his Harvard classmates in his knowledge of the frontiers of chemistry. But he was quick to catch up.

Bard arrived at Harvard thinking he wanted to study inorganic chemistry. He was fascinated by the then-new field of organometallic sandwich compounds and joined the group of assistant professor Geoffrey Wilkinson, who was engaged in work on these compounds that would earn him a Nobel Prize in Chemistry in 1973.

Unfortunately for Bard, Wilkinson's days at Harvard were numbered. The chemistry department's practice at the time was to not offer tenure to its own assistant professors, including Wilkinson, who left at the end of 1955 to accept the chair in inorganic chemistry at Imperial College, London. The incident made a strong impression on Bard, who would soon choose to launch his own academic career at a less prestigious university than Harvard, but one where tenure was likely if he proved his worth.

Wilkinson's departure had another important impact on Bard's career. "I realized I wasn't so intrigued about doing inorganic chemistry," he says. Looking for a new research adviser gave him a chance to change fields and to move toward analytical chemistry, which, he felt, would be a better fit for him. The work of electrochemist James J. Lingane captured his imagination, and in 1956 Bard joined Lingane's group, earning a master's degree under Lingane's mentorship in 1956 and a doctorate two years later.

Electrochemistry "turned out to be a really lucky choice for me," Bard says. "I've always liked electronics and electrical circuits, and I think I have an aptitude for electrochemistry, probably much more so than for inorganic synthesis, organic synthesis, or some other field."

Bard arrived in Austin to join the faculty of UT as a chemistry instructor in 1958, with his brand-new doctoral degree. He had never been to Texas. Austin, then something of a sleepy cow town, was quite a change for a native New Yorker.

Bard and his wife, Fran, a fellow New Yorker whom he married in his last year of graduate school, have made Austin their home. Both of their children, Ed and Sara, were born in Texas. They now have five grandchildren.

Those who know his work don't expect Bard's scientific accomplishments to fade away anytime soon.

COMING TO TEXAS "was almost a lark," Bard says. "Things were different then. The university didn't give me any start-up money to speak of. I got $5,000 to set myself up, which wasn't a huge commitment on their side. And I didn't feel a huge commitment either. I would come down, see what it was like, and try to get started. If I didn't like it, I figured I could go somewhere else."

Of the university itself, Bard says, "I thought, frankly, it was a pretty mediocre place at the time. But I thought it had all the potential. It was in a state that had good resources. I knew the chairman of the chemistry department--Norman Hackerman--and I was impressed with his work. He was an electrochemist, too."

Hackerman, now an emeritus professor, offered Bard a teaching position without even bringing him in for the customary interview. "I thought he was an obvious person to get down here," Hackerman recalls. "He had done his Ph.D. work with a top-notch analytical chemist, and his dissertation and his early papers all had the mark of very reliable research. There was no point wasting his time or ours with an interview. If he was interested, he'd come.

"And he did have the qualities I was told he had," Hackerman says. "He's made some very important contributions to our understanding of electrochemistry, interface chemistry, and chemistry in general."

One of Bard's strengths, Hackerman points out, is an ability to recognize the potential of new instrumentation to address the problems he's interested in. "Bard would immediately jump on new and innovative instruments and work with them quite effectively. And he's still doing that. That has given him an edge. He sees things differently than they have been seen before because he has more sensitive instrumentation."

Hackerman adds: "He also has persistence. He has these long series of papers--sometimes going up to roman numeral 48 or so--that have allowed him to develop various subfields very effectively. In some cases he wasn't the only one developing the subfield, but his contribution is broad and always good. I don't think he's written a bad paper, in the sense of being a nonentity--one that doesn't make some contribution. And he's written, I don't know, 400 of them, maybe."

In fact, it's well over 600 and growing. Although Bard's research might all be classed as electrochemistry, it covers that field very broadly, from the practical to the more theoretical, and from solar cells to new analytical techniques.

It's hard to overestimate the respect other chemists have for Bard's research. "In my opinion," Caltech's Anson says, "Bard ranks as the most outstanding electrochemist of the last half of the 20th century. No one else has taught us as much about organic electrochemistry, electrochemistry of polymers, semiconductor photoelectrochemistry, mechanistic electrochemistry, and electrochemistry on the nanoscale as has Allen Bard."

Inorganic chemist Mark S. Wrighton, now chancellor of Washington University, St. Louis, says Bard's work has "transformed the field of electrochemistry and has captured the interest of every segment of the discipline of chemistry." The work has practical significance in areas such as fuel cells, solar energy conversion systems, display technology, and sensors, Wrighton notes. "Most important, Bard's basic research has had a great contribution to the fundamental understanding of chemical reactions which occur at electrodes."

COMMENTING ON the range of his work, Bard says, "I like to have broad interests because I think it's good for students. It's much better for a student to have a problem that has a lot of broad aspects to it and to hear from other people in the group who are working on other things. I want to create an environment that broadens students and gives them a good view of chemistry."

There's another reason for breadth, Bard notes. "I've discovered," he says, "that research doesn't follow a straight line. It goes in hops and jumps as you understand things, discover things, and see new possibilities. When I see where I am now and where I was 43 years ago, there's no connection that I would have ever foreseen."

Upon arriving at Texas, "I was interested in the application of electrochemical methods to chemical problems. I felt that electrochemistry had a lot of important applications, like batteries; even in those days, fuel cells; and electroplating. But I wasn't terrifically interested in those applications. I thought one could use electrochemistry to probe chemical systems. And I felt there was a real disconnect between electrochemists and all the other chemists. Organic chemists, inorganic chemists, physical chemists didn't really see electrochemistry making wide contributions to the field anymore."

In particular, Bard wanted to use electrochemistry to study organic systems. By working in nonaqueous solvents, he was able to probe the mechanisms of organic reactions occurring at electrodes. "We discovered quickly that we could understand a lot of organic chemistry through a molecular orbital approach, where you inject an electron in and pull an electron out of a molecule," he explains.

"That was not a popular idea at the time," Bard points out. In the late 1950s, the strength of organic chemistry was embodied in the ideas of people like Sir Christopher Ingold, who were explaining organic reactions by looking at the movement of pairs of electrons. "What we were finding was that electrons would also go in and out of molecules one at a time. You could make radical cations and radical anions that were perfectly stable, as long as there wasn't any oxygen or water around. We were among the first to use vacuum line techniques, and later dry boxes, in electrochemistry, so we could get really clean, dry, and air-free systems."

8014bard.college 8014bard 8014bard.portrait

THROUGH THE YEARS In graduate school in 1955, as a professor at UT Austin in 1972, and as JACS editor in 1994.

MORE AND MORE, Bard says, he and his students were establishing a molecular basis for electrochemical phenomena. "We were starting," he says, "to understand things based on molecular properties that you could calculate."

In the mid-1960s, the Bard group and several others began to wonder what would happen if a radical anion and a radical cation were brought together. The idea was to watch what happened in this very energetic reaction as electrons transferred from one ion to the other.

"What we discovered was that this electron-transfer reaction generates an excited state and gives out light. You could do electrochemistry and generate light," he says.

Bard discovered the phenomenon, now called electrogenerated chemiluminescence (ECL), independently. But other researchers were discovering ECL at essentially the same time. By chance, one of the other groups was headed by Bard's former Harvard roommate, Edwin A. Chandross, then at Bell Laboratories. A third group to make the discovery essentially simultaneously was that of David M. Hercules and his colleagues at Massachusetts Institute of Technology.

His own contribution to this field, Bard suggests, rests not so much in being first as in being persistent. "Others gave up rather quickly because they didn't see any applications, and Bell Labs, in particular, was interested in applications," Bard explains. "But I was just so fascinated with it. It was so much fun to do, and it was a very good field for students because they would learn electrochemistry, but they would also have to learn some spectroscopy, photochemistry, and so on."

As an analytical chemist, Bard wanted to find a way to use ECL as an analytical technique. But initially the phenomenon could only be carried out in organic solvents and under conditions that rigorously excluded water. None of the early compounds that gave ECL were soluble in water, and most reacted with it.

In the early 1970s, Bard began experimenting with a metal ion complex capable of luminescence, ruthenium tris-bipyridyl ion, Ru(bpy)32+. This ion could be used to produce ECL in polar solvents like acetonitrile, but generating both the oxidizing and reducing radical ions needed for ECL in water has its own special challenges. Bard and his students eventually overcame that difficulty as well. In recent work, they have developed ECL into a highly sensitive and selective analytical technique for biological applications, such as immunoassays and quantitative DNA analysis.

Along the way, they have tried a number of what may, or may not, turn out to be false starts. One characteristic of Bard's research is that he returns to the same problems over and over again, reinterpreting results in the light of new insights coming from his own and other laboratories.

In the late 1960s, for example, Bard and his students incorporated Ru(bpy)32+ and other organic compounds into polymer films that could generate light. The work predates the development of the inorganic light-emitting diodes that are in widespread use today. "Even then, the idea of having small, light-emitting devices for displays and so on was interesting," Bard says. But these early systems were not stable enough for practical applications. Interest is returning to this field, however, thanks to much work on organic light-emitting systems in many laboratories. "Ru(bpy)32+ works well as a light-emitting device, and we're still studying it," Bard says.

In fact, after nearly 30 years of investigation, Bard says, ECL "is still a very fascinating field. We are still learning things about the way these systems work."

THE WORK HAS LED Bard into several new research directions. For example, he recalls a conversation in about 1970 with Farrington Daniels, then a chemistry professor at the University of Wisconsin. "Daniels said, 'Anybody can put electricity into something and make light come out. That's not really a big deal. The big deal is to put light into a system and make electricity come out. Can you run your system backwards?' "

At the time, Bard says, he didn't have any idea how to run the system backwards. "But it got me to thinking: How would you make a system go the other way? So we slowly, slowly got into the field of photoelectrochemistry, which is putting light into systems and getting electricity and chemicals out of them."

For 25 years, Bard and his students have been investigating photoelectrochemistry, studying both semiconductors and other molecular materials. One of their biggest contributions to this field was to demonstrate that semiconductors don't have to be highly pure, single-crystal materials. As is well accepted now, polycrystalline materials, even powders, can serve as catalysts for photoelectrochemical reactions. Bard and his group not only did some of the first experiments using polycrystalline semiconductors, but also developed much of the theoretical understanding of the electrochemistry involved. They have helped explore useful applications as well, such as the incorporation of semiconductor particles into polymer films for solar energy conversion devices.

Semiconductor particles can also be used as catalysts for photochemical reactions, as Bard and his students have shown. Their 1977 experiments using titanium dioxide powders and sunlight to oxidize cyanide, and later organic pollutants, in water opened the way to this approach to wastewater treatment.

"One of our interests has always been to understand the electrode-solution interface and to be able to look at that with very high resolution," Bard says. "So when I saw the 1981 paper from Gerd Binnig and Heinrich Rohrer on scanning tunneling microscopy (STM), we immediately got interested in that, to see if we could apply it to electrochemistry. At that time, the only studies that had been done were in air or in a vacuum, and people told us, 'It's not going to work in solution.' But we decided, 'Well, we'll try it anyway.' "

As Bard and others were to show, STM can be done in solution. "We got the idea that maybe we could also use electrochemical probes of the same type," Bard says. "Instead of doing tunneling spectroscopy, we might be able to use electrochemistry to study interfaces and processes." The result was a technique Bard named scanning electrochemical microscopy, now widely used to study interfaces.

Current work in the Bard lab attempts to use scanning electrochemical microscopy and similar techniques to study biological systems. One project under way is trying to combine scanning electrochemical microscopy with near-field scanning optical microscopy. In the former, a metal tip serves as an electrochemical probe to scan a surface, detecting changes in electrochemical properties. In the latter, the resolution of an optical microscope is increased by squeezing laser light through a quartz fiber that's thinner than the wavelength of light passing through it. "We are trying to combine the two techniques by taking a quartz fiber and coating it with an electrode material, so that we can measure both optical and electrical properties of a surface at the same time," Bard explains. "It's a difficult problem." If it can be done, the combination could lead to a tool that could be used to generate reactants electrochemically and optically watch them interact with substrates.

"Our dream--which we are nowhere near--is to be able to image ions passing through an individual ion channel in a cell membrane," Bard says. "To do that, we will need much higher resolution and higher sensitivity than we have right now. But we are trying."

Work on organic thin films is also ongoing in Bard's lab. "We really don't understand the electronic properties of these films," he says. "We understand a lot about the electronic properties of inorganic films, but there are some really big surprises in the things we find when we make very thin organic films. For example, you can get charge in and trap it there, so that you can do electrochemistry in solids, in a sense. We're just in the early stages of studying that."

He's also interested in the light-emitting properties of these films. "We have cells that give out light, but they don't last, and we don't know why," Bard explains. "We would like to be able to make them last longer, but we also want to know just how much chemistry can go on in these films."


KID STUFF Bard helps grandson Alex investigate electrochemistry.

OUTSIDE OF THE analytical chemistry community, Bard is probably best known for his 20 years of service as the editor of JACS, a position he stepped down from last December.

Compared with the JACS of 1982, when Bard took the helm, today's JACS covers chemistry much more broadly, says Peter J. Stang, the journal's current editor. "JACS publishes more in the materials area, for example," Stang points out. "It has much more in analytical chemistry and in physical chemistry than it used to have. Not only did Bard maintain and enhance the excellence of JACS, but he broadened its scope. And he did this at a time when the publishing world was becoming more competitive."

Stang adds: "He does a first-rate job. He's always very, very fair and very considerate of authors."

Bard spent two years as an associate editor for JACS before he became editor, experience that he says helped him to appreciate how much support the journal's editor has and to see how he might fill that role.

"JACS has always been a good journal," Bard says. "It's easy to take over a good journal. I wanted to maintain the very high standard in the papers that were in it, and I think we've done that. But I also wanted to make it a more general journal."

Having worked on JACS essentially daily for two decades, Bard says he may be too close to the journal to see just how it's changed during that period. "It's certainly gotten much bigger," he says, "and more international." Some changes have not been conscious editorial decisions, he points out. Rather, they reflect the changing face of chemistry itself.

Coming full circle, it may be Bard's former students and colleagues who provide the most accurate insight into this man. "Besides science, Allen teaches fairness, tolerance, loyalty, and the importance of intellect and hard work," two of his former students--Richard M. Crooks and Henry S. White, now chemistry professors at Texas A&M University and the University of Utah, respectively--wrote in a special issue of the Journal of Physical Chemistry in 1998 that was dedicated to Bard.

"He's extremely creative, really smart, and he works really hard," Crooks adds. "This is, I think, driven by his passion for science and a craving to understand as much as he can about how nature works."

As former colleague Marye Anne Fox puts it, "There's nothing to be learned about being a professional in chemistry that you can't learn from Allen Bard."

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