It isn't easy BN aromatic! 1,2‐Dihydro‐1,2‐azaborine, a hybrid organic/inorganic benzene, is a stable aromatic molecule with features that are distinct from its isoelectronic “organic” (benzene) and “inorganic” (borazine) counterparts. Experimental structural, spectroscopic, and chemical data are fully supported by high‐level calculations.

There is emerging evidence that growth of synthetic and natural phases occurs by the aggregation of prenucleation clusters, rather than classical atom-by-atom growth. Ferrihydrite, an iron oxyhydroxide mineral, is the common form of Fe(3+) in soils and is also in the ferritin protein. We isolated a 10 angstrom discrete iron-oxo cluster (known as the Keggin ion, Fe13) that has the same structural features as ferrihydrite. The stabilization and manipulation of this highly reactive polyanion in water is controlled exclusively by its counterions. Upon dissolution of Fe13 in water with precipitation of its protecting Bi(3+)-counterions, it rapidly aggregates to ~22 angstrom spherical ferrihydrite nanoparticles. Fe13 may therefore also be a prenucleation cluster for ferrihydrite formation in natural systems, including by microbial and cellular processes.

The first cobalt molecule to function as a single-molecule magnet, [Co 4 (hmp) 4 (MeOH) 4 Cl 4 ], where hmpis the anion of hydroxymethylpyridine, is reported.The core of the molecule consists of four Co(II) cations and four hmpoxygen atoms ions at the corners of a cube. Variable-field and variable-temperature magnetization data have been analyzed to establish that the molecule has a S=6 ground state with considerable negative magnetoanisotropy. Single-ion zero-field interactions (DS z 2 ) at each cobalt ion are the origin of the negative magnetoanisotropy. A single-crystal of the compound was studied by means of a micro-SQUID magnetometer in the range of 0.040-1.0K.Hysteresis was found in the magnetization versus magnetic field response of this single crystal. It is concluded that this is the first cobalt molecule to function as a singlemolecule magnet.

Extended carbon nanostructures, such as carbon nanotubes (CNTs), exhibit remarkable properties but are difficult to synthesize uniformly. Herein, we present a new class of carbon nanomaterials constructed via the bottomup self-assembly of cylindrical, atomically precise small molecules. Guided by supramolecular design principles and circle packing theory, we have designed and synthesized a fluorinated nanohoop that, in the solid state, self-assembles into nanotube-like arrays with channel diameters of precisely 1.63 nm. A mild solution-casting technique is then used to construct vertical "forests" of these arrays on a highly ordered pyrolytic graphite (HOPG) surface through epitaxial growth. Furthermore, we show that a basic property of nanohoops, fluorescence, is readily transferred to the bulk phase, implying that the properties of these materials can be directly altered via precise functionalization of their nanohoop building blocks. The strategy presented is expected to have broader applications in the development of new graphitic nanomaterials with π-rich cavities reminiscent of CNTs.

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