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Subnanometric metal particles exhibit anomalous chemical activity, suggesting innovative applications as next-generation materials. However, a precise synthesis and detailed characterisation of these subnano-materials remain a major challenge. Here we summarise recent works on the synthesis of size-controlled tin (Sn) oxide subnanoparticles (SNPs) using the dendrimer template method, and on their detailed characterisation. Size-controlled Sn oxide SNPs (Sn12, Sn28 and Sn60) have been synthesised and they showed a size-dependent compositional change containing not only stable Sn(iv) states but also metastable Sn(ii) states so as to form subnano-scaled particle shapes. Detailed vibrational characterisation of SNPs was achieved by employing subnano-sensitive Raman spectroscopy for spectroscopic characterisation. Combined with density functional theory studies, the inherent subnano-structures of Sn oxide SNPs have been elucidated for the first time. Furthermore, the size-dependent activity of Sn oxide SNPs upon CO oxidation was rationally explained from the simulated structure of Sn oxide SNPs. A detailed understanding of the chemical and physical nature of subnano-materials facilitates the rational design of SNPs for practical applications such as catalysis, biosensors, and electronics.

IR light irradiation of a mixed toluene solution of ammonium salt-stabilized gold nanoparticles with 3.8 ± 0.8 nm core diameter and a porphyrin thioacetate derivative affords a thin photoactive film of the cluster–porphyrin network.

Fullerene is strongly adsorbed on both single crystal and polycrystalline gold surfaces and its specific adsorption resulted in the formation of high coverage large hexagonal rafts with strong interactions between the adsorbed fullerene molecules and the Au substrate. The oxygen reduction reaction (ORR) was investigated on these surfaces to determine their influence on the reduction mechanism. Oxygen reduction did not take place on the fullerene overlayer but proceeded on the sub-nanometer sized exposed pockets of the underlying Au substrate. Reduction at these confined sites produces hydrogen peroxide selectively. This effect is ascribed to the blocking action, or so-called "third body effect", of the adsorbed fullerene molecules, which do not display electrocatalytic properties for oxygen reduction.

Copper underpotential deposition (Cu UPD) and STM studies have been carried out on fullerene (C60) modified Au single crystal surfaces to determine the influence of crystal orientation on the structure of adsorbed C60 overlayers. High coverage could be achieved for C60 on all the surfaces studied, Au(111), Au(332) and Au(554). In each case, hexagonal and/or quasi-hexagonal arrays of adsorbed C60 were formed, with distortion from the ideal hexagonal packing arising from the constrained width of the terraces of the stepped surfaces. The structural parameters of the C60 overlayers were found to be sensitive to the terrace width.