Modeling of Supramolecular Systems, Mechanically Docked to Carbon Nanotubes
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0924-Z08-06
Modeling of Supramolecular Systems, Mechanically Docked to Carbon Nanotubes J. C. Poler, and T. D, DuBois Chemistry, UNC Charlotte, 9201 University City Blvd., Charlotte, NC, 28223 ABSTRACT Carbon nanotubes and nanowires are important materials for new nanotechnology devices and sensors. Future optoelectronic devices can be made from assemblies of nanostructured materials. One difficulty in preparing these assemblies from nanotubes is the lack of site-specific points of contact and the subsequent compliance of the linkage between nanoparticles. Using molecular mechanics, semiempirical and dynamics calculations, we have modeled the assembly process of two-dimensional and three-dimensional structures of carbon nanotubes. The linkers between the nanotubes consist of novel metallodendrimers. These dendrimers have multiple binding sites with chemically specified chirality. Most importantly, they are mechanically rigid. This enables the multidimensional constraints and geometry, required for advanced electronic and optoelectronic devices.
INTRODUCTION Carbon nanotubes and nanowires are important materials for technology devices and sensors. Nanoelectronic devices can be made from assemblies of nanostructured materials. One difficulty in preparing these assemblies is the lack of site-specific points of contact and the subsequent compliance of the linkages between the nanotubes or nanoparticles. Thus, the assembly of nanotubes into preconceived three dimensional structures (self assembly) is quite challenging. With that said, the structural and optical isomers of inert transition metal complexes, i.e., transition metal complexes resistant to ligand exchange, provide an attractive array of molecular scaffolds or points of contact for the attachment of nanotubes. Prime candidates for the construction of molecular scaffolds are found in the inert d6 octahedral complexes of cobalt(III) and ruthenium(II) and the square planar d8 complexes of platinum(II). While many of these complexes are isolated as cationic salts, structurally rigid neutral and anionic complexes containing inert metal centers can be prepared by the careful selection of the metal center and the proper number of anionic and neutral ligands. In this paper we report some computational results and observations concerning the interaction of small hydrogen terminated single walled carbon nanotubes (SWCNTs) with MacDonnall’s dendrimer and other three dimensional dimeric, trimeric, etc. complexes generated by the controlled assembly of different optically active octahedral ruthenium(II) centers.1,2 COMPUTATIONAL METHODS Calculations were performed using the suite of programs contained within the SPARTAN 04 computational package and the suite of programs contained within Gaussian 03 for Windows.3, 4 Molecular dynamics calculations were performed by exporting SPARTAN files with structures optimized at the semiempirical PM3 level into Odyssey.5
RESULTS AND DISCUSSION The Λ and ∆ isomers of tris(1,10-phenathroline)ruthenium(II) dication optimize to a struct
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