Building Robust and Reliable Molecular Constructs: Patterning, Metallic Contacts, and Layer-by-Layer Assembly

We describe recent progress in our laboratories to build stable complex two- and three-dimensional molecular constructs. We have introduced a simple and robust method for constructing complex molecular devices using top-down and bottom-up techniques based on self-assembled monolayers (SAMs), lithography, and site-selective reactions. It has significant advantages over other methods; it is easily scaled up, affords precise nanoscale placement, and is extensible to many different materials. Several recent developments are discussed including the UV photopatterning and electron beam lithography of SAMs adsorbed on semiconductors, the site-selective deposition of metals using electroless deposition and low-temperature chemical vapor deposition, and layer-by-layer assembly using covalent coupling. Optimization and further development of these techniques requires a detailed understanding of the reaction pathways involved in the lithography of SAMs and of the interaction of SAMs with metals, organometallic compounds, ions, and other compounds.