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.

Fresh ideas have always been a necessary ingredient for progress in chemistry. Without a continuous supply of stimulating ideas from creative researchers, there would be no new insights into the subject. But what are some of the ideas that pervade modern chemistry? The answer to this question is to be found in "Stimulating Concepts in Chemistry". In a collection of 24 essays, a group of leading researchers provides an overview of the most recent developments in their fields. Readers can find out about modern concepts in chemistry such as self-assembly, nanochemistry, and molecular machines. Moreover, many spectacular advances have been achieved from the fusion of chemistry with life and materials science - a development which is illustrated by contributions on enzyme mimics, molecular wires, and chemical sensors. Further, the essayists write about new nanomaterials, efficient methods in synthesis, and big biomolecules - indeed, many of the topics that have dominated some of the recent discussions in chemistry. This outstanding text makes use of a special layout to reflect the editors' aim of presenting concepts in the form of essays. Thus, the book is not merely another source of knowledge but is intended to stimulate readers to develop their own ideas and concepts. This format should help to make the book interesting to a wide range of scientists. Students of chemistry will benefit from the different style of presentation of their subject, while researchers in industry and academia will welcome the exciting way in which some of the most challenging concepts in modern chemistry are presented.

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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.