Superconductivity in aromatic hydrocarbons

Short Synthesis of [5]‐ and [7]Phenacenes with Silyl Groups at the Axis Positions

“…[7d] This synthesis consisted of ruthenium-catalyzed direct CÀHa rylation, [12] followed by sequential Wittig olefination and bismuth-catalyzed cyclization of the resulting vinyl ethers (Scheme 3). [13] Based on this success, we initially attempted the synthesis of 3,10-disilyl [5]phenacene( 2)a nd 3,12-disilyl [7]phenacene (3)t hrough as imilar three-step synthesis strategy. However,i nt he first reactiont hat we attempted, the ruthenium-catalyzed direct CÀHa rylations of aldimines that were derived from 3-silylbenzaldehyde with 1,4-dibromobenzene (Scheme 4a)o r1 ,8-diformylphenanthrenew ith bromo-4-silyl-benzene (Scheme 4b)d id not proceed efficiently.…”

“…[3,4] Because of their low HOMO energies, thesecompounds exhibit improved chemical stability under ambientc onditions compared with their isostructural analogues, [n]acenes. Further-more, [5]phenacene (picene) is the first hydrocarbon to show unique superconductivity through intercalation with an alkali metal. [5] The importance of [n]phenacenes means that an efficient route is required fort he direct synthesis of suitably functionalized [n]phenacenes from simple buildingb locks in fewer steps.…”

“…Further-more, [5]phenacene (picene) is the first hydrocarbon to show unique superconductivity through intercalation with an alkali metal. [5] The importance of [n]phenacenes means that an efficient route is required fort he direct synthesis of suitably functionalized [n]phenacenes from simple buildingb locks in fewer steps. However,a lthough numerouss tudies have investigated the transition-metal-catalyzed synthesis of fused polyaromatic hydrocarbons, [6] their application to the short and efficient synthesis of functionalized[ n]phenacenes has so far been limited.…”

“…[7] To further develop the unique properties of [n]phenacenes, we investigated short transition-metal-catalyzed syntheses of [n]phenacenes that contained appropriate functional groups at the axis positions. Thisd esign was inspired by ar ecent mobility study of 3,10-di(tetradecyl) [5]phenacene (1a)b yK ubozono and co-workers( Scheme 1). [4e] The hole mobility of compound 1a reached 20 cm 2 V À1 s À1 (average value:1 4cm 2 V À1 s À1 ), the second-highest among p-channelo rganic thin-film FETs.…”

Superconducting materials classes: Introduction and overview

“…P6: Superconductivity in aromatic molecules was suggested a long time ago by Fritz London. In 2010, it was finally found in alkali doped aromatic hydrocarbons, as reviewed by Kubozono and coworkers [31], for example, K x picene (five benzene rings) with T c ∼ 18K. The authors point out that for this class of materials, the shielding fraction is usually very low and the highest priority research is to increase it.…”