CORRESPONDENCE The 2000 Nobel Prize in ChemistryÐ A Personal Accolade Joel S. Miller*[a]

The discovery and development of con- Institute of Technology, led to the forma- This section contains correspondence of publications ductive polymers has just been awarded in ChemPhysChem and material, written on invitation, tion of lustrous silver films of polyacety- the 2000 Noble Prize in Chemistry in on topics of high current interest. Other correpond- lene. Currently he is Professor Emeritus at Stockholm. This stunning, paradigm-shift- ence is welcomed if it contributes to scientific the Institute for Materials Science at the discussion. The editior reserves the right to select what ing discovery was made at the University shall appear. University of Tsukuba, where he has been of Pennsylvania by chemists Alan G. since 1979. The error was the use of the MacDiarmid and Hideki Shirakawa and spawned a flurry of activity worldwide Ziegler ± Natta catalyst a thousand times physicist Alan J. Heeger in 1977. The aimed at seeking new materials with more concentrated than previously used. revelation that polymeric materials could enhanced properties and, as a conse- Although Shirakawa's research interests provide additional function far beyond quence, related electron-transfer, salt- were far removed from conducting poly- the well established structural and me- based organic superconductors were first mers, he shared his then-new discovery chanical properties continues to engen- reported in 1980.[5] with MacDiarmid, who was visiting the der exciting new opportunities for future With soluble organic-based conductors institute. MacDiarmid shared the poten- electronic, optoelectronic, as well as pho- established extension to polymers were tial importance of this observation with tonic devices. Commercial products are inevitable. The lustrous, highly reflecting Kenneth J. Wynne, of the U.S. Office of emerging that are based on conductive inorganic polymer, poly8sulfur nitride) or Naval Research who concurred and was polymers. 8SN)x, was reported to exhibit metallike the first to fund research on conducting Conductive polymers evolved from conductivity between 2.4 and 300 K,[6] polymers. MacDiarmid seized the oppor- earlier studies on organic electron-trans- and even superconductivity at 0.26 K,[7] tunity to invite Shirakawa to join him in fer salts that exhibited high direct-current but it lacked the ability to be modified his laboratory to jointly study the elec- electrical conductivity at room temper- akin to organic polymers. Hence, en- trical and optical properties of the films ature. Organic conductors, described as hanced electrical conductivity via chem- with him and Heeger at the University of ªorganic amalgamsº, were first envisioned ical modification as well as improved Pennsylvania; Heeger subsequently four decades[1] prior to the 1954 report chemical stability and processing could moved to his current position at the that perylene electron-transfer salts with not be achieved for 8SN)x. Conjugated University of California, Santa Barbara. bromine exhibited high electrical con- polymers, akin to poly8sulfur nitride) but The rest, of course, is history. ductivity.[2] Independently, while search- unlike saturated polymers such as poly- Unsurprisingly, polyacetylene was a ing for new polymers akin to Teflon, ethylene, could be envisioned to be semiconductor; however, upon reaction Du Pont researchers discovered that elec- conductive. These polymers, however, with iodine, among other oxidants, a tron-transfer salts of TCNQ 87,7,8,8-tetra- had to be in a useful form and partially greater than million-fold enhancement cyano-p-quinodimethane) also produced oxidizable 8or reducable). The Ziegler ± in the electrical conductivity was ach- highly conducting materials.[3] Metallike Natta polymerization of acetylene to form ieved. This oxidation process was termed conductivity, that is, an increase in con- polyacetylene was well established but ªdopingº in accord with the enhancement ductivity with decreasing temperature, the polyacetylene was only available as a of the conductivity of semiconductors. was observed a few years later in a TCNQ powder. This remarkable observation altered in a complex containing an electron-transfer A fortuitous error on the part of Hideki permanent way how organic chemists salt.[4] These highly conducting materials Shirakawa in 1975, then of the Tokyo viewed the old reaction of iodination of double bonds for extended systems. This seminal workwas essentially published [8] and presented simultaneously. Along with Arthur J. Epstein, Alan G. MacDiar- mid, and Henry Taube, I chaired the Conference on Synthesis and Properties

[a] Prof. J. S. Miller Department of Chemistry University of Utah Salt Lake City, UT 84112 6USA) Fax: 6‡1)801-581-8433 Alan J. Heeger Alan G. MacDiarmid Hideki Shirakawa E-mail: [email protected]

CHEMPHYSCHEM 2000, 1, 229 ± 230  WILEY-VCH-Verlag GmbH, D-69451 Weinheim, 2000 1439-4235/00/01/04 $ 17.50+.50/0 229 J. S. Miller of Low-Dimensional Materials sponsored turned. It vanished from my office and in- effect transistors[14] and ªplastic chipsº[15] by the New YorkAcademy of Sciences. [9] depth sleuthing led to identification that are being pushed towards commerciali- This meeting had a strong chemical focus the custodial staff deemed it as garbage zation. Clearly, conductive polymers cer- and provided the ideal forum for dissem- and promptly discarded it. Even after tainly have a bright, if not illuminating, ination of the then-revolutionary discov- sifting through numerous trash deposito- future and their discoverers, Alan G. ery of their conducting organic polymer. ries, we failed to recover it. My sadness MacDiarmid, Hideki Shirakawa, and Alan This stunning result was highlighted in over this loss continues to be exasperated J. Heeger, certainly deserve the high the press.[10] as the importance of this sample increas- accolade bestowed by the Noble Foun- The area encompassing conducting es with time. But Alan MacDiarmid was as dation for their seminal discovery. organic materials has grown exponential- gracious as ever and well understood my ly through the years, as illustrated by a torment. snapshot of the interests and number of Applications and commercialization of attendees at its biennial international organic conductors were never distant [1] a) H. N. McCoy, W. C. Moore, J. Am. Chem. Soc. conferences. The interests have migrated and today are on the research and devel- 1911, 33, 273; b) H. Kraus, J. Am. Chem. Soc. 1913, 34, 1732. from electron-transfer salts and linear opment forefront. Amusingly, the early [2] H. Akamatsu, H. Inokuchi, Y. Matsunaga, chain metal-based soluble conductors expectation to use them as battery ma- Nature 1954, 173, 168. and their associated physics and chem- terials was not sustainable, while a ple- [3] a) D. S. Acker, R. J. Harder, W. R. Hertler, W. istry issues to the solid-state physics of thora of unexpected applications Mahler, L. R. Melby, R. E. Benson, W. E. Mochel, J. Am. Chem. Soc. 1960, 82, 6408; b) R. G. [11] polyacetylene on to the development of evolved. These include polypyrrole- Kepler, P. E. Bierstedt, R. E. Merrifield, Phys. new classes of conducting polymers and based electrolytic capacitors, polyaniline- Rev. Lett. 1960, 5, 503. their electrochemical p- and n-doping, based high capacity floppy disks, poly- [4] L. R. Melby, Can. J. Chem. 1965, 43, 1448. polymer physics, chemical modifications, pyrrole-based conductive coatings for [5] D. Jerome, A. Mazaud, M. Ribault, K. Bech- gaard, J. Phys. Lett. 6Paris) 1980, 41, L45. and materials processing properties. The textile, polypyrrole-based copper plating [6] V. V. Walatka, Jr., M. M. Labes, J. H. Perlstein, available conducting polymers expanded baths for printed circuit boards, and Phys. Rev. Lett. 1973, 31, 1139. to include poly8p-phenylene), polythio- polyaniline-based antistatic coatings. In [7] R. L. Green, G. B. Street, L. J. Sutter, Phys. Rev. phene, polypyrrole, polyaniline, and poly- the waning years of the twentieth cen- Lett. 1975, 34, 557. [8] H. Shirakawa, E. J. Louis, A. G. MacDiarmid, 8p-phenylenevinylene), to name a few, tury, new conductive polymer-based or- C. K. Chiang, A. J. Heeger, J. Chem. Soc. Chem. with several of them presently commer- ganic light emitting diodes 8LED) beck- Comm. 1977, 579. cially used. Due to its instability, neither p- oned. In 1990, Richard Friend's group at [9] ªSynthesis and Properties of Low-Dimension- nor n-ªdopedº polyacetylene itself has Cambridge University reported light was al Materialsº in Ann. N.Y. Acad. Sci. 8Eds.: J. S. Miller, A. J. Epstein), 1978, p. 313. any commercial appeal. produced upon application of an electri- [10] J. H. Kreiger, Chem. Eng. News 1977, 55827), 14. An early sample of highly reflecting cal potential to a conductive polymer;[12] [11] J. S. Miller, Adv. Mater. 1993, 5, 587, 671. ªdopedº polyacetylene, perhaps destined this was similar to the light produced with [12] J. H. Burroughes, D. D. C. Bradley, A. R. Brown, for a major science museum such as the application of an applied voltage to an R. N. Marks, K. Mackay, R. H. Friend, P. L. Burns, A. B. Holmes, Nature 1990, 347, 539. Franklin Institute or even the Smithsoni- anthracene crystal that was reported from [13] M. Pope, H. P. Kallmann, P. Magnante, J. Chem. an, that was prepared in MacDiarmid's Martin Pope's laboratory in 1962.[13] Today, Phys. 1963, 38, 2042. laboratory, was lost forever. I personally numerous groups worldwide are working [14] a) G. Horowitz, Adv. Mater. 1990, 2, 287; b) G. take the blame. At my request, Alan feverishly to commercialize a myriad of Horowitz, X-Z. Peng, D. Fichou, F. Garnier, J. Mole Electron. 1991, 7, 85. MacDiarmid kindly sent me his remaining products based on thin-film organic LEDs. [15] G. H. Gelinck, T. C. T. Geuns, D. M. de Leeuw, sample, which was to be promptly re- Likewise, organic devices such as field- Appl. Phys. Lett. 2000, 77, 1487.

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