Over the past ten years, there has been tremendous progress
in the measurement, modeling and understanding of structure-function
relationships in single molecule circuits. Experimental techniques for
reliable and reproducible single molecule junction formation and
characterization have led, in part, to this progress. In particular, the
scanning tunneling microscope based break-junction technique has enabled
rapid, sequential measurement of large numbers of nanoscale junctions
allowing a statistical analysis to readily distinguish reproducible
characteristics. In this talk, I will present methods to create
single-molecule devices and measured their physical properties,
including electronic, electrochemical and thermoelectric. I will then
show how their molecular structure as well as the environment around
these nanoscale systems can control their electronic characteristics.