Understanding the mechanism of nanoparticle self-assembly is of critical significance for developing synthetic strategies for complex nanostructures. By encapsulating aggregates of Au nanospheres in shells of polystyrene-block-poly(acrylic acid), we prevent the dissociation and aggregation typically associated with the drying of solution samples on TEM/SEM substrates. In our study of the salt-induced aggregation of 2-naphthalenethiol-functionalized Au nanospheres in DMF, the trapping of the solution species under various experimental conditions permits new insights in the mechanism thereof. We provide evidence that the spontaneous linear aggregation in this system is a kinetically controlled process and hence the long-range charge repulsion at the "transition state" before the actual contact of the Au nanospheres is the key factor. Thus, the charge repulsion potential (i.e. the activation energy) a nanosphere must overcome before attaching to either end of a nanochain is smaller than attaching on its sides, which has been previously established. This factor alone could give rise to the selective end-on attachment and lead to the linear assembly of originally isotropic Au nanospheres.

A central theme in nanotechnology is to advance the fundamental understanding of nanoscale component assembly, thereby allowing rational structural design that may lead to materials with novel properties and functions. nanoparticles (nPs) are often regarded as 'artificial atoms', but their 'reactions' are not readily controllable. Here, we demonstrate a complete nanoreaction system whereby colloidal nPs are rationally assembled and purified. Two types of functionalized gold nPs (A and B) are bonded to give specific products AB, AB 2 , AB 3 and AB 4 . The stoichiometry control is realized by fine-tuning the charge repulsion among the B-nPs. The products are protected by a polymer, which allows their isolation in high purity. The integration of hetero-assembly, stoichiometry control, protection scheme and separation method may provide a scalable way to fabricate sophisticated nanostructures.

The first charge-transfer complexes of tetrathiafulvalene (1) with 1,2,5-chalcogenadiazole derivatives, i.e. with [1,2,5]thiadiazolo [3,4-c][1,2,5]thiadiazole (2) and 3,4-dicyano-1,2,5-telluradiazole (3), were prepared in the form of single crystals and structurally defined by X-ray diffraction as 1·2 and 1·3 2 , respectively. Starting compound 2 was synthesized by a new efficient method from 3,4-diamino-1,2,5-oxadiazole and disulfur dichloride. The electronic structure and UV-vis spectral properties of complexes 1·2 and 1·3 2 were studied by means of DFT 2 calculations. The electrical properties of single crystals of the complexes were investigated revealing semiconductor properties with an activation energy of 0.34 eV for 1·2 and 0.40 eV for 1·3 2 . Both complexes displayed photoconductive effects with increased conductivity under white-light illumination.3

The synthesis of a terpyridine-guanosine ligand and its reaction with copper(II) to yield a new [2 + 2] metallo-rectangle is reported. The metallo-rectangle was characterized by single crystal X-ray diffraction and the structure showed significant intramolecular π-π stacking interactions between the two terpyridine moieties of the molecule. This prompted us to investigate the magnetic properties of the new di-copper(II) assembly which displayed ferromagnetic interactions in the solid state.

Electrochemical deposition has been used to prepare a thin film of neutral 4',4-(3-alkyl)-thiophene-5',5-hydogen-nickel and copper dithiolenes (Ni-C2, Cu-C2). The application of molecular electrodeposition provides a means to solution process molecular semiconductors of poor solubility, which results from the strong intermolecular interaction required for charge transport. Both Ni-C2 and Cu-C2 form continuous thin films that show intense NIR absorptions, extending to 1800 nm and 2000 nm respectively giving evidence for the strong intermolecular interactions in the solid state. Both films are highly conducting and temperature dependence of resistance gave an activation energy of 0.42 eV and 0.072 eV respectively, with the near-metallic behaviour of Cu-C2 attributed to the additional presence of an unpaired electron.