Surface capped clusters

Hiratani, T., Konishi, K., Surface cap-mediated host-guest chemistry of semiconductor CdS Intercalative cation accumulation around a phenyl-capped CdS cluster and its notable effects on the cluster photoluminescence. Angew. Chem., Int. Ed. 2004, 43, 5943-5946. 

In an extension of this work, we have considered the bonding in bispherical and multispherical clusters where the skeletal atoms lie on the surfaces of two or more concentric spheres15713. This type of model may be used to analyse face-capped clusters. In bispherical cases, it was found that the presence of a ring (either planar or puckered) around the... 

During the past decade, a new focus has developed. It was found that semiconductor particles can be made so small, typically into the nanometer size regime, that a quantum confinement effect occurs [6-15]. Particles of this size are often referred to as nanoclusters, nanoparticles, quantum dots, or Q-particles. The structures of these nanometer-sized semiconductor clusters are usually similar to those of the bulk crystals, yet their properties are remarkably different. With the proper surface-capping agents, clusters of varying sizes can be isolated as powders and redissolved into various organic solvents just like molecules. The availability of this new class of materials allows us to study the transition of a material from molecule to bulk solid, as well as its various properties and applications. 

FIG U RE 10.4 Geometry of a sphere cap nucleating on a solid surface. The cluster of radius R forms a contact angle 0 with the porous surface. 

Herron, N., Wang, Y., and Eckert, H. (1990). Synthesis and Characterization of Surface-Capped Size-Quantized CdS Cluser. Chemical Control Cluster Size. J. Am. Chem. Soc. 112, 1322-1326. 

DiLabio GA, Wolkow RA, Johnson ER (2005) Efficient silicon surface and cluster modeling using quantum capping potentials. J Chem Phys 122 5... 

Addition of either nucleophilic or electrophilic metallic species can result in the capping of triangular- or square-metal faces in carbonyl clusters. These redox reactions provide high yield syntheses of higher nuclearity clusters and somewhat resemble surface reconstruction on metals. With a few examples,... 

Based on the same principle, there are monomeric / -helical proteins that carry at their extremities a cluster of helical or nonrepetitive structures that could act as a capping element covering their exposed ends (Emsley et al., 1996 Lietzke et al, 1994 Petersen et al, 1997 Steinbacher et al, 1994). For example, the last 40 residues of pectate lyase C form a large loop that partially covers the surface of the /Hielix (Yoder et al, 1993). The fibrous (or otherwise elongated) domain of these natural /f-stranded proteins is not stable in isolation, as for example in the case of the P22 tailspike where bacterially expressed isolated /Hielix domain, at high concentrations, forms fibrous aggregates that bind Congo red (Schuler et al, 1999). 

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