New functional twists for P 450 s


caesium-doped phenanthrene, prepared by Yasuhiro Takabayashi and colleagues through a second synthetic route9. In this case, the reaction of caesium with the PAH was carried out in solution, affording highly pure crystalline samples of CsxPhenanthrene, with x = 1 or 2. Although Cs2Phenanthrene (x = 2) remains a nonmagnetic insulator, analogous to the K2PAH samples discussed above, CsPhenanthrene (x = 1) is shown to exhibit quantum spin-liquid behaviour. In this rare and exotic magnetic phase, no longrange magnetic order is possible and the magnetic frustration, which persists even down to the lowest measured temperatures, supports unconventional excitations with fractional quantum numbers such as spinons. The experimental realization of such a quantum phase — materials that are currently discussed as a suitable platform for performing calculations in quantum computers — is, however, very scarce. With CsPhenanthrene, Takabayashi and co-workers propose a possible new spinliquid candidate and directly demonstrate the potential for further exploration of these materials, for which high-quality samples are now attainable. Stepping back, this work continues a long history of materials research in organic carbon-based systems. In 1911, Herbert McCoy and William Moore had already advanced the idea that suitably prepared organic materials could support unpaired electrons, granting them conductivity combined with magnetic properties analogous to those of metals10. It was not until the 1950s and 60s, however, that this prediction was experimentally realized, with the discovery of semiconducting behaviour in doped PAHs. By the 1970s, the utility of doping to introduce charge-carrying electrons was fully established, through the report of metallic conductivity in polyacetylene treated with halide vapours11 — a development that ultimately earned Alan Heeger, Alan MacDiarmid and Hideki Shirakawa the 2000 Nobel Prize in Chemistry. Around this time, Robert Haddon posited that superconductivity should also be realizable in PAH materials12, pre-empting later discoveries in the 1980s and 90s. These culminated in the achievement of record-high superconducting transition temperatures exceeding 30 K in alkali-doped C60 (refs 13,14). Over the intervening time, the development of organic electronics has been pursued in earnest, inspiring far-reaching advances from organic semiconductors to light-emitting devices, to the emergence of graphene and carbon nanotubes. The present advancements in synthetic methods, 26 years since the first inspiring reports of superconducting buckyballs, now firmly establish alkalidoped PAHs as attractive species to explore novel material science. ❐

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Cite this paper

@inproceedings{Takabayashi2017NewFT, title={New functional twists for P 450 s}, author={Yasuhiro Takabayashi and Alan J. Heeger and Alan G. MacDiarmid and Hideki Shirakawa}, year={2017} }