Efforts to identify and develop new superconducting materials continue apace, motivated by both fundamental science and the prospects for application. For example, several new superconducting material systems have been developed in the recent past, including calcium-intercalated graphite compounds, boron-doped diamond and-most prominently-iron arsenides such as LaO(1-x)F(x)FeAs (ref. 3). In the case of organic superconductors, however, no new material system with a high superconducting transition temperature (T(c)) has been discovered in the past decade. Here we report that intercalating an alkali metal into picene, a wide-bandgap semiconducting solid hydrocarbon, produces metallic behaviour and superconductivity. Solid potassium-intercalated picene (K(x)picene) shows T(c) values of 7 K and 18 K, depending on the metal content. The drop of magnetization in K(x)picene solids at the transition temperature is sharp (<2 K), similar to the behaviour of Ca-intercalated graphite. The T(c) of 18 K is comparable to that of K-intercalated C(60) (ref. 4). This discovery of superconductivity in K(x)picene shows that organic hydrocarbons are promising candidates for improved T(c) values.

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Interest in metal oxide semiconductors for energy processes has increased due to their prominent roles in photocatalysis, electrical energy storage, and conversion. However, an understanding of the thermochemistry of electron transfer (ET) reactions of these systems has lagged behind photophysical studies. This report investigates ET equilibria between reduced forms of well-characterized, ligated ZnO and TiO2 nanoparticles (NPs) suspended in toluene. Multiple electrons were added to each type of NP, either photochemically or with a chemical reductant. Equilibration experiments monitoring these added electrons are used to construct a qualitative band diagram. Surprisingly, the difference between the “reducible” oxide TiO2 and the formally “nonreducible” ZnO is reflected not in the relative band energies but rather in the relative width of the bands (the density of trap and/or band states). Moreover, the position of the electron equilibrium shifts upon addition of excess dodecylamine or oleic acid capping ligands. The directions of the equilibrium shifts suggest that they are due to the acid/base or hydrogen bond donor/acceptor properties of capping ligands. This suggests a coupling of protons with the electron transfers in these systems. These findings provide a more nuanced and detailed picture of ET thermodynamic landscapes at nanoparticles than what is provided in a typical nanoparticle band energy scheme. Aspects of this understanding could be valuable for the use of nanoscale oxides in energy technologies.

A new cobalt(ii) complex bearing a pair of cobalt(iii) tris-chelate complexes as metalloligands was prepared. The CoII ion possesses an ideal trigonal antiprismatic geometry because of the intermolecular hydrogen-bonds between the metalloligands via counter anions. This complex exhibits slow magnetic relaxation under a dc field reminiscent of a single-molecule magnet behavior.