The group's research focuses on surface chemistry, self-assembly of two- and three-dimensional structures, and molecular electronics. The main experimental techniques used are inorganic/organic synthesis, CMOS processing, and physical and analytical measurements of surface or materials properties. Scanning tunneling microscopy, atomic force microscopy, electrochemistry, X-ray photoelectron spectroscopy, and optical spectroscopy are used to get insight into the structure and electronic properties of molecules on surfaces or inside materials. The group's work is quite interdisciplinary and we collaborate with several groups in the College of Engineering

DNA nanotechnology

We are studying fundamental materials issues for the integration of self-assembling DNA nanostructures (DNA lattices, tiles, or origami) with top-down CMOS fabrication methods. DNA-templated assembly of electronic components offers several possible wins as a patterning technology for nanoelectronics. Self-assembly of DNA can create objects on the scale of 10-100 nm as well as repeating grids or meshes that cover several square microns. Design principles are sufficiently understood such that DNA nanostructures with novel, arbitrary shapes can move from concept to reality in about 2 weeks. Students with an interest in synthetic chemistry can tackle the integration of non-DNA components with DNA nanostructures, while students with more of a physical or analytical focus can address fundamental questions about the yields, error types, and ultimate utility of self-assembly.

Guided assembly of biomolecules and nanoparticles

Electron-beam lithography is used in very high resolution CMOS fabrication processes. We are developing methodology to use the electron beam to chemically pattern a surface, and then to deposit biomolecules upon the very tiny chemical patterns. Biomolecules of interest include proteins, virus particles, and DNA.

Self-Assembling Monolayers of Phthalocyanines

Phthalocyanines are similar to porphyrins; like porphyrins, they can be synthesized using a metal ion as a template. Functional groups that can bind to a gold or SiO₂ surfaces are introduced either at the periphery of the ring (as the OR groups), or in an axial position(as the R' group or by substitution of the axial chloride). When a smooth gold surface is soaked in solutions of these phthalocyanines, a single molecular monolayer is formed. Ways to control the orientation of the phthalocyanine rings on the surface are being explored; this is a general problem in surface chemistry which the highly anisotropic phthalocyanines are well suited to probe.

"Shish-kebab" polymers in which phthalocyanine rings are covalently connected through axial interactions are also being made. With properly chosen peripheral substituents, the rod-like polymers are soluble in organic solvents. They are similar in diameter to carbon nanotubes. However, unlike carbon nanotubes, they can be synthesized with some control over their composition and surface properties. These one-dimensional semiconductors act as sensors for gaseous chlorine and nitrogen oxides and are also of interest as light-harvesting antennae for organic photovoltaic cells.