Network Approaches to Highly Porous Materials: Metal-organic frameworks (MOFs), in which inorganic centers are bridged by organic linkers, can achieve very high porosity for gas absorption. However, as the materials develop larger void spaces, there is also more room for growing interpenetrating networks—filling the open spaces not with gas molecules but with more MOFs. Furukawa et al. (p. 424 , published online 1 July) describe the synthesis of a MOF in which zinc centers are bridged with long, highly conjugated organic linkers, but in which the overall symmetry of the networks created prevents formation of interpenetrating networks. Extremely high surface areas and storage capacities for hydrogen, carbon dioxide, and methane were observed.

Covalently linked cyclic porphyrin arrays have been explored in recent years as artificial photosynthetic antenna. In this review we present the fundamental aspects of covalently linked cyclic porphyrin arrays by highlighting recent progress. The major emphasis of this tutorial review lies on the synthetic method, the structure, and the excitation energy transfer (EET) of such arrays. The final cyclization steps were often performed with the aid of templates. Efficient EET along the wheel is observed in these cyclic arrays, but ultrafast EET processes with rates of <1 ps, which rival those in the natural LH2, are rare and have been identified only in cyclic arrays 30–32 composed of directly meso–meso linked porphyrins.