The ultimate computational system would consist of logic devices that are ultra dense, ultra fast, and molecular-sized. Even though state-of-the-art nanopatterning techniques allow lithographic probe assemblies to be engineered down to the 100 A gap regime, the issue of electronic conduction based upon single or small packets of molecules has not been addressed and the feasibility of molecular electronics remains theoretically controversial. In an attempt to assess the possibility of molecular wire conduction by spanning the 100 A probe gaps with small packets of molecules, we describe here the synthesis of phenylene-alkynylene oligomers that remain in a near-linear conformation due to 1,4-phenylene- substitution patterns and alkyne linearity. This linear arrangement should minimize undesired conformational movement during adhesion and testing between nanofabricated probes. Our approach to such a molecular framework involves a rapid iterative method that doubles molecular length at each iteration to provide an air and light-stable linear conjugated oligomer that is 128 A long that could also serve as a useful model for understanding bulk polymeric material properties. Moreover, the product could easily permit independent functionalization of the ends to serve as "molecular alligator clips" that might be required for surface contacts to metal probes for molecular electronic studies. jg p. 3.

Described is the synthesis of oligo(2-ethylphenylene-ethynylene)s and oligo(2-(3'ethylheptyl)phenylene-ethynylene)s via an iterative divergent convergent approach. Synthesized were the monomer, dimer, tetramer, and octamer of the ethyl derivative and the monomer, dimer, tetramer, octamer, and 16-mer of the ethylheptyl derivative. The 16-mer is 128 A long. At each stage in the iteration, the length of the framework doubles. Only three sets of reaction conditions are needed for the entire iterative synthetic sequence; an iodination, a protodesilylation, and a Pd/Cu-catalyzed cross coupling. The oligomers were characterized spectroscopically and by mass spectrometry. The optical properties are presented which show the stage of optical absorbance saturation. The size exclusion chromatography values for the number average weights, relative to polystyrene, illustrate the tremendous differences in the hydrodynamic volume of these rigid rod oligomers verses the random coils of polystyrene. These differences become quite apparent at the octamer stage. These oligomers may act as molecular wires in molecular electronic devices and they also serve as useful models for understanding related bulk polymers.

PPV materials are very stable and can be further functionalized along their main-chains, however due to shorter effective conjugations lengths (smaller than that of the oligoenes), the range of electronic tunability is smaller in these materials. In addition to this family of symmetric molecules other asymmetric oligoene molecules were synthesized as candidates for single-molecule rectification. These molecules allow different electronic coupling to the right and left electrodes, which may modulate their IV characteristics.

Provides in-depth knowledge on molecular electronics and emphasizes the techniques for designing molecular junctions with controlled functionalities This comprehensive book covers the major advances with the most general applicability in the field of molecular electronic devices. It emphasizes new insights into the development of efficient platform methodologies for building such reliable devices with desired functionalities through the combination of programmed bottom-up self-assembly and sophisticated top-down device fabrication. It also helps to develop an understanding of the device fabrication processes and the characteristics of the resulting electrode-molecule interface. Beginning with an introduction to the subject, Molecular-Scale Electronics: Concept, Fabrication and Applications offers full chapter coverage on topics such as: Metal Electrodes for Molecular Electronics; Carbon Electrodes for Molecular Electronics; Other Electrodes for Molecular Electronics; Novel Phenomena in Single-Molecule Junctions; and Supramolecular Interactions in Single-Molecule Junctions. Other chapters discuss Theoretical Aspects for Electron Transport through Molecular Junctions; Characterization Techniques for Molecular Electronics; and Integrating Molecular Functionalities into Electrical Circuits. The book finishes with a summary of the primary challenges facing the field and offers an outlook at its future. * Summarizes a number of different approaches for forming molecular-scale junctions and discusses various experimental techniques for examining these nanoscale circuits in detail * Gives overview of characterization techniques and theoretical simulations for molecular electronics * Highlights the major contributions and new concepts of integrating molecular functionalities into electrical circuits * Provides a critical discussion of limitations and main challenges that still exist for the development of molecular electronics * Suited for readers studying or doing research in the broad fields of Nano/molecular electronics and other device-related fields Molecular-Scale Electronics is an excellent book for materials scientists, electrochemists, electronics engineers, physical chemists, polymer chemists, and solid-state chemists. It will also benefit physicists, semiconductor physicists, engineering scientists, and surface chemists.

Described is the synthesis of oligo(3-ethylthiophene-ethynylene)s via an iterative divergent convergent approach starting from 3-ethyl-2- (trimethylsilylethynyl)thiophene. Synthesized were the monomer, dimer, tetramer, octamer and 16-mer. The 16-mer is approximately 100 A long in its minimum energy conformational form. At each stage in the iteration, the length of the framework doubles. Only three sets of reaction conditions are needed for the entire iterative synthetic sequence; an iodination, a protodesilylation, and a Pd/Cu- catalyzed cross coupling. The oligomers were characterized spectroscopically and the mass spectrometry data are discussed. The optical properties are presented which show that at the octamer stage, the optical absorbance maximum is nearly saturated. The size exclusion chromatography values for the number average weights, relative to polystyrene, illustrate the tremendous differences in the hydrodynamic volume of these rigid rod oligomers versus the random coils of polystyrene. These differences become quite apparent at the octamer stage. The rigid rod conjugated oligomers may act as molecular wires in molecular electronic devices and they also serve as useful models for understanding analogous bulk polymers.