Explorations of benzene-based organic superconductors and bismuth-based functional materials are today's hottest topics in chemistry, physics, and materials science.Here, we show that by doping potassium into an organobismuth molecule, tri-p-tolylbismuthine, which is composed of one bismuth atom and three methylphenyl groups, all synthesized samples exhibit type-II superconductivity at 3.6 K at ambient pressure and one sample also shows superconductivity at 5.3 K. The common 3.6 K superconducting phase is identified to have a triclinic P1 structure, with a mole ratio of 3:1 between potassium and tri-p-tolylbismuthine. The calculated electronic structure indicates that superconductivity is produced by transferring an electron from K 4s to the C 2p orbital, which results in both red and blue shifts of the Raman spectra. Our study enriches the physical functionality of organobismuth compounds and illustrates a new route for the search of organic superconductors.

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Superconductivity with a Tc of 3.6 K observed in K-doped o-TTB and the molecular arrangement of K-doped o-TTB.

The rich physical properties of metal-intercalated polycyclic aromatic hydrocarbon materials have recently attracted considerable attention. Crystals of potassium-intercalated 2,7-dimethylnaphthalene were synthesized via solid phase reaction. The combination of XRD measurements and first-principles calculations indicated that each unit cell contains two potassium atoms and four organic molecules. Magnetization measurements revealed that the samples show a Curie paramagnetism. Theoretical calculations showed that the intercalated structure becomes metallic and has local magnetic moment. Raman spectroscopy confirmed the migration of electron from potassium 4s to carbon 2p orbital, which is the source of magnetism. Our research on naphthalene derivatives is helpful for expanding the range of novel organic magnetic materials and organic superconducting materials.

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