The design and construction of some simple mechanical nanostructures based on the use of main group polyhedra has been investigated. A common synthetic subunit (synthon) has been designed and synthesized which can be electronically and geometrically modified during its synthesis or by post-synthetic substitution to customize the properties required in the fabrication of a variety of larger structural systems. The structures of proposed synthons have been geometry optimized using MOPAC97 at the AM1 level of theory. The geometry optimization of the described nanostructures has been completed using Augmented Molecular Mechanics (MM2/MM3) force fields.
Cluster complexes provide a wealth of desirable properties suitable for the design and synthesis of nanoscale components, including thermal stability, electronic polarization and delocalization throughout the clusters, chemical stability under a variety of conditions, and significant geometric flexibility, allowing these components to be incorporated into yet larger molecular systems. With the wide range of main group clusters available, it is possible to design many intricate nanoscale structures from cluster-based subunits, avoiding the severe synthetic difficulties which arise from atomic manipulation methods. Beyond the structural benefits of main group clusters, the electronic properties of these systems are becoming increasingly noticed for their roles as components of nonlinear optical (NLO) materials1-6.
The model synthons have been designed to display many useful structural and electronic properties, including significant electronic delocalization between clusters, selective electronic insulation and conduction between the clusters and the attached molecular fragments, and geometric features which provide for linkage of the synthons into large-scale molecular architectures. From the properties designed into the synthons, a variety of larger-scale electronic and structural effects can be considered.
In this paper, we will present our recent work using polyhedral materials in nanoscale component fabrication and molecular NLO applications.
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