Keywords: nanotechnology, nanoparticles, molecular electronics, particle chromatography, particle electrophoresis.

While significant effort has been made to synthesize molecular wires for electronic applications, the ability to insert these molecules between two metallic contacts with directional control has yet to be demonstrated. Control over molecular orientation is critical to the development of molecular devices such as diodes, capacitors and transistors. In this study, directional control is achieved using orthogonal self-assembly to synthesize electronic junctions between nanoparticles of different compositions. Phenyl ethynylene oligomers were synthesized with different end groups. One molecule was functionalized with a thiol which exhibits preferential binding to gold and an isocyanide which exhibits preferential binding to platinum. The other was functionalized with a thiol for binding to gold and a carboxylic acid which exhibits preferential binding to metal oxides. One of the major challenges of this work was the synthesis of nanoparticle building blocks that were suitable for the formation of these heterodimeric structures. Metal and metal oxide particles were synthesized with capping ligands that provided stability yet did not sterically hinder heterodimer formation. Once appropriate nanoparticles had been identified, preliminary studies indicated heterodimer formation. However, characterizing these structures presented additional challenges. Several characterization techniques, including transmission electron microscopy (TEM), size-exclusion chromatography (SEC), several types of electrophoresis and small-angle x-ray scattering (SAXS), were evaluated for their ability to characterize these structures with statistical accuracy. While all of these techniques did indicate the presence of dimers or larger aggregates in solution, accurate statistical information was not obtained using any single method.

Chemically synthesized nanostructured materials have the potential to impact fields ranging from energy conversion, electronics, and catalysis to fields such as chemical sensing, biotechnology and health care. This body of work describes the synthesis and characterization of two classes of chemically synthesized nanostructured materials with designed/tunable optical and electronic properties--mesostructured oxides and nanoparticle assemblies.

Keywords: molecular electronics, nanoparticles, orthogonal self-assembly.

The integration of top-down lithographic techniques with synthetic organic and inorganic technologies is a key challenge for the development of effective nanosca1e devices. In terms of assembly, nanoparticles provide an excellent tool for bridging the gap between the resolution of electron beam lithography (-60 nm) and the molecular level. Nanoparticles possess an array of unique properties associated with their core materials, including distinctive magnetic, photonic and electronic behavior. This behavior can be controlled and applied through monolayer functionalization and assembly strategies, making nanoparticles both scaffolds and building blocks for nanotechnology. The diverse structures and properties of nanoparticles makes them useful tools for both fundamental studies and pragmatic applications in a range of disciplines. This volume is intended to provide an integrated overview of the synthesis and assembly of nanoparticles, and their applications in chemistry, biology, and materials science. The first three chapters focus on the creation and intrinsic properties of nanoparticles, covering some of the myriad core materials and shapes that have been created. The remaining chapters of the book discuss the assembly of nanoparticles, and applications of both discrete particles and particle assemblies in a wide range of fields, including device and sensor fabrication, catalysis, biology, and nanosca1e electronic and magnetic systems.

Cubes, triangular prisms, nano-acorn, nano-centipedes, nanoshells, nano-whiskers. . . . Now that we can create nanoparticles in a wide variety of shapes and morphologies, comes the next challenge: finding ways to organize this collection of particles into larger and more complex systems. Nanoparticle Assemblies and Superstructures, edit

Nanocrystals research has been an area of significant interest lately, due to the wide variety of potential applications in semiconductor, optical and biomedical fields. This book consists of a collection of research work on nanocrystals processing and characterization of their structural, optical, electronic, magnetic and mechanical properties. Various methods for nanocrystals synthesis are discussed in the book. Size-dependent properties such as quantum confinement, superparamagnetism have been observed in semiconductor and magnetic nanoparticles. Nanocrystals incorporated into different material systems have proven to possess improved properties. A review of the exciting outcomes nanoparticles study has provided indicates further accomplishments in the near future.