Dr. Jiliang Zhang
Department of Chemistry
University of Liverpool, United Kingdom
Superconductivity has recently been reported in alkali metal (AM) intercalated polyaromatic hydrocarbons (PAHs) synthesized in solid state reactions, with a maximum superconducting temperature of 33 K reported in potassium-doped 1,2:8,9-dibenzopentacene. These systems attract great interest as a novel superconducting family. However, reproducibility of the reported products is poor and no crystal structures have been reported. In most cases, reactions between potassium metal and PAHs yield potassium hydride as a major product instead of the reported compounds, suggesting that strongly reducing conditions at high temperature disrupt the s-bonding of the PAH. Here I would like to present the synthesis of potassium intercalated rubrene compounds K2R (R=rubrene), and characterization of both the amorphous and crystalline components of complex mixtures, characteristic of many intercalated PAH systems.
The systematic investigation of Potassium-Rubrene solid state reactions using both K and KH sources reveals complex competition between K intercalation and decomposition of rubrene. The result provides a guideline to achieve AM-intercalated PAHs in both redox chemistry and metallurgy. With the guideline, we successfully synthesized other intercalated compounds of different PAHs (tetracene, pentacene and picene) with AMs (Li, K, Cs). Crystal structures of these compounds are also well characterized and some properties are expected based on their structures, despite the absence of superconductivity.