Fred Wudl. Discovering new science through making new molecules

This special issue of the Journal of Materials Chemistry is a tribute to one of the pioneers of the field, Professor Fred Wudl, on the occasion of his 70^th birthday. Fred was born in 1941 in Bolivia in a family of German immigrants. As a high school student he made his way to the United States and graduated with a BSc in chemistry from University of California at Los Angeles (UCLA) in 1964. Three years later, in 1967, he obtained his PhD, also from UCLA, working with Donald Cram. After a short post-doctoral stay at Harvard University with Robert Woodward, he accepted an assistant professorship at State University of New York at Buffalo in 1968. In the first few years of his independent career he synthesized tetrathiafulvalene (TTF)¹ and demonstrated high electrical conductivity of its ion radical salts²—a finding that soon led to the famous organic metal TTF:TCNQ and the first organic superconductors. The idea of rational chemical design of electronic materials has attracted hundreds of organic chemists to the field. Over 7000 TTF derivatives, and even more of its complexes and analogues have been synthesized to date.

In 1972 Fred accepted a research staff position at Bell Labs—which at the time was one of the world leading materials research centers. Fred himself described this move as one of the smartest decisions of his life. There, he continued working on conducting molecular solids and received worldwide recognition as one of the fathers of the field.

In 1982 the call of an academic “duty” (or possibly the grey skies of the New Jersey winters) brought Fred back to California, where he joined UC-Santa Barbara. There, Fred also started to work on conducting polymers and formed an incredibly powerful scientific alliance with physicist Alan Heeger—a collaboration that led (and still leads) to a wide variety of key contributions in the field of conjugated polymers. This work includes pioneering studies on chemical synthesis³ and electrochemical doping of polythiophenes,⁴ the first low band-gap polymer (poly(isothianaphthene)),⁵ organic-⁶ and water-soluble⁷ conjugated polymers, among others. Two papers co-authored by Wudl and Heeger on fast electron transfer in conjugated polymer/[60]fullerene systems⁸ and on bulk heterojunction solar cells thereof,⁹ which gave rise to a completely new field of research and applications, have been cited over 4000 times.

When the fullerene era sparkled, Fred was there, studying the incredible soccer ball-shaped molecule from all materials and organic chemistry sides. Again, his group was the first to discover that C₆₀ is an electron-poor compound, exhibiting high reactivity toward nucleophiles. Therefore, when they mixed the strong donor tetrakis(dimethylamino)ethylene (TDAE) with C₆₀, they found an organic molecular ferromagnet, with a Curie temperature T_C = 16.1 K.¹⁰ Analogously, the synthesis of “fulleroids”, produced by allowing C₆₀ to react with diazo compounds, gave rise to the first family of systematically functionalized fullerene derivatives.¹¹ The entire field of fullerene functionalization boomed since then, with his group contributing continuously with new and exciting discoveries, such as the “azafullerenes”.¹²

In 1997 Fred moved to UCLA, where he founded the Institute for Exotic Materials, a name which fits pretty well with his personality. Only an “exotic” and outstanding scientist can grab a bark sample from a tree, while walking with his lovely wife in a wonderful Japanese garden, put it in his pocket, and one year later publish two papers describing the unusual morphology and the mechanical properties of that sample.^13,14 Very few things could be farther away from organic electronics, the main direction of Fred's research, but his creativity was never limited by the perceived “discipline boundaries”. In fact, one of Fred's key contributions in the last decade was the discovery of self-mending polymers that are capable of “healing” fractures developed under stress, upon gentle heating.¹⁵ Totally different from anything else done in his lab before, this work has marked the first application of dynamic covalent chemistry (Diels–Alder cyclization) to make smart materials.

Later, in 2006 Fred returned to Santa Barbara to join the new Institute for Nanoscience in UCSB, where he continues making new advanced materials and developing new science while, at the same time, educating the next generation of students in understanding chemistry as a personal challenge, as he always did.

With an astonishing h-index of 85, Fred is one of the most cited living chemists on the planet. He is a Fellow of the American Association for the Advancement of Science and received numerous prestigious awards including the American Chemical Society (ACS) Arthur C. Cope Scholar Award, the ACS Award for Chemistry of Materials, the Tolman Medal and most recently the Stephanie L. Kwolek Award from the Royal Society of Chemistry. His name is exceptionally well-recognized around the world and a number of well established academics, particularly from Europe and Japan, have spent time in Fred's lab (Fig. 1). Fig. 2 shows the ceremony at Universidad Complutense in Madrid, Spain where Fred was awarded the Doctor Honoris Causa degree.

Fig. 1 Fred Wudl with friends and former co-workers at a conference in Espinho, Portugal, September 1997. From left to right: Conceptio Rovira, Andreas Hirsch, Fernando Langa, Fred Wudl, Maurizio Prato, Nazario Martin, Kees Hummelen and Angela Sastre. Most, if not all, of these academics had their careers boosted after having worked in Fred Wudl's lab at UCSB.

Fig. 2 Fred Wudl (second from the left) at the ceremony awarding him Doctor Honoris Causa from Universidad Complutense in Madrid, Spain.

His impact goes beyond the over 500 published papers. His creativity and unconditional love for science have had a tremendous influence on his former students, post-docs, collaborators and colleagues, many of whom are themselves world leaders in the field of organic materials. The breadth of this impact is also evident from the diversity of the 41 papers contributed to this issue by Fred's co-workers, colleagues and friends, which cover various areas of organic, inorganic and biomaterials. Their contributions to this issue is an acknowledgement of Fred's pioneering role as a scientist in shaping what Materials Chemistry is today and his role as a mentor or a friend in shaping their research careers. In fact, what makes Fred “superspecial” is his human side. Beyond his “what's the story”, during the years, he has cared in a fatherly manner about his collaborators, following their work closely after they left Fred's group, giving suitable advice on how to develop their careers and supporting them on all occasions.

We conclude noting that the story is not finished yet. Prof. Wudl and his group continue to surprise us with new and revolutionary findings and discoveries. In January 2011 many of us will gather in Santa Barbara to celebrate Fred's birthday at a special symposium “Advances in Organic Electronics”—and we are certain it will not pass by without Fred sharing some of his latest results and ideas. For sure “what's the story?” will continue to stimulate us for many coming years.

Happy Birthday, Fred, and many more to come!

Michael Bendikov

Nazario Martin

Dmitrii F. Perepichka

Maurizio Prato

References

1. F. Wudl, G. M. Smith and E. J. Hufnagel, Bis-1,3-Dithiolium Chloride—An Unusually Stable Organic Radical Cation, J. Chem. Soc. D, Chem. Comm., 1970, 1453.
2. F. Wudl, D. Wobschal and E. J. Hufnagel, Electrical Conductivity by the Bis-1,3-Dithiole-Bis-1,3-Dithiolium System, J. Am. Chem. Soc., 1972, 94, 670.
3. M. Kobayashi, J. Chen, T. C. Chung, F. Moraes, A. J. Heeger and F. Wudl, Synthesis and Properties of Chemically Coupled Poly(Thiophene), Synth. Met., 1984, 9, 77.
4. T. C. Chung, J. H. Kaufman, A. J. Heeger and F. Wudl, Charge Storage In Doped Poly(Thiophene)—Optical and Electrochemical Studies, Phys. Rev. B: Condens. Matter, 1984, 30, 702.
5. F. Wudl, M. Kobayashi and A. J. Heeger, Poly(Isothianaphthene), J. Org. Chem., 1984, 49, 3382.
6. S. Hotta, D. D. V. Rughooputh, A. J. Heeger and F. Wudl, Spectroscopic Studies of Soluble Poly(3-Alkylthienylenes), Macromolecules, 1987, 20, 212.
7. A. O. Patil, Y. Ikenoue, F. Wudl and A. J. Heeger, Water-Soluble Conducting Polymers, J. Am. Chem. Soc., 1987, 109, 1858.
8. N. S. Sariciftci, L. Smilowitz, A. J. Heeger and F. Wudl, Photoinduced Electron-Transfer from a Conducting Polymer to Buckminsterfullerene, Science, 1992, 258, 1474.
9. G. Yu, J. Gao, J. C. Hummelen, F. Wudl and A. J. Heeger, Polymer Photovoltaic Cells—Enhanced Efficiencies via a Network of Internal Donor–Acceptor Heterojunctions, Science, 1995, 270, 1789.
10. P. M. Allemand, K. C. Khemani, A. Koch, F. Wudl, K. Holczer, S. Donovan, G. Gruner and J. D. Thompson, Organic Molecular Soft Ferromagnetism in a Fullerene-C₆₀, Science, 1991, 253, 301.
11. T. Suzuki, Q. Li, K. C. Khemani, F. Wudl and O. Almarsson, Systematic Inflation of Buckminsterfullerene C₆₀—Synthesis of Diphenyl Fulleroids C₆₁ to C₆₆, Science, 1991, 254, 1186.
12. J. C. Hummelen, B. Knight, J. Pavlovich, R. Gonzalez and F. Wudl, Isolation of the Heterofullerene C₅₉N as Its Dimer (C₅₉N)₂, Science, 1995, 269, 1554.
13. X. Xu, E. Schneider, A. T. Chien and F. Wudl, Nature's High-Strength Semitransparent Film: The Remarkable Mechanical Properties of Prunus serrula Bark, Chem. Mater., 1997, 9, 1906.
14. X. Xu, E. Schneider, C. Zaremba, G. D. Stucky and F. Wudl, Modification of the Semitransparent Prunus serrula Bark Film: Making Rubber out of Bark, Chem. Mater., 1998, 10, 3523.
15. X. Chen, M. A. Dam, K. Ono, A. Mal, H. Shen, S. R. Nutt, K. Sheran and F. Wudl, A Thermally Re-mendable Cross-Linked Polymeric Material, Science, 2002, 295, 1698.

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