Organic rechargeable batteries have received significant research interest from the viewpoints of structural diversity and sustainability of electrode materials. We designed core structures of organic cathode materials for lithium-ion (Li-ion) batteries based on density functional theory (DFT) calculations, which indicated that six-membered cyclic 1,2-diketones serve as excellent core structures because of the high redox energy change resulting from favorable coordination of the oxygen atoms to Li and the aromaticity of the reduced form. Here, we show that the Li-ion battery composed of pyrene-4,5,9,10-tetraone (PYT), which has two six-membered cyclic 1,2-diketone units, bound to polymethacrylate exhibits remarkable charge-discharge properties with a high specific capacity of 231 mAh/g, excellent rechargeability (83% of the capacity retained after 500 cycles), and charge-discharge ability (90% of the capacity at 30 C as compared to 1 C) in the LiNTf(2)/tetraglyme ionic-liquid system.

A teranthene derivative has been successfully isolated in a crystalline form for the first time. Geometrical considerations and physical property investigations indicate that the molecule possesses prominent biradical character in the ground state.

Ones and twos: The two‐photon absorption cross sections (σ(2)) of singlet diradical hydrocarbons with phenalenyl peripheral groups (see scheme) are larger than those of closed‐shell aromatic hydrocarbons by an order of magnitude or more and are comparable to those of π‐conjugated compounds with strong electron donor or acceptor substituents. A significant increase in cross section was also observed in the resonance‐enhanced region.

A phenalenyl‐based Kekulé hydrocarbon with singlet biradical character has been isolated and characterized. Strong intra‐ and intermolecular interactions between the unpaired electrons lead to short π–π contacts and formation of one‐dimensional chains (see picture). Thus, wide valence and conduction bands are established, and the compound shows semiconductive behavior.