Researchers at Penn State have flipped the switch -- the molecular switch.

A team of scientists from Penn State, Rice University, and the University of Oregon has found a way to turn molecules on and off. Their research shows how single-molecule switches can be customized to react in predictable ways. The discovery of the molecular switch is a crucial step in bettering the future of molecular electronics.

Paul Weiss, researcher and distinguished professor of chemistry and physics, said a molecular switch can change its conductivity at any given voltage.

"It's a single molecule that can have two states -- an on state and an off state," said James Tour, fellow researcher and professor of chemistry at Rice University. "There are several mechanisms of a molecular switch," he said. "The molecules tilt toward the surface to give two states."

A paper titled "Molecular Engineering of the Polarity and Interactions of Molecular Electronic Switches" will be published on Dec. 21 in the Journal of the American Chemical Society.

Weiss tested the molecules in the basement of Davey Laboratory. The switches might be used with real electronics in the future, but not until someone discovers a way to wire them.

The research team includes Weiss, Tour and Francisco Maya of Rice University, Penelope Lewis of Columbia University, and James Hutchison and Christina Inman of the University of Oregon.

The researchers split their work into three parts: making the switches, developing a matrix to hold the switches in place and studying the switches.

The team has confirmed that it has the predictive power to design molecular switches that can be turned on or off at will.

Some of the switches have high conduction while others are less conductive, Weiss said.

Conduction is the movement of electrically charged particles through a medium. Molecular switches change how conductive it is in a given atmosphere.

In their research, Weiss and his team studied synthetic organic molecules called oligo phenylene-ethynylenes (OPEs). The scientists modified the strands in a number of ways to have a variety of physical, chemical and electronic characteristics.

The possibility of using the OPE molecules as switches was limited by their troublesome tendency to turn on and off at random. The team reduced the random switching when it found how to control the molecular switches by placing the molecules in a matrix of similarly shaped molecules and observing them under a powerful scanning tunneling microscope (STM).

A molecular surface system is responsible for the switching, Weiss said.

Molecular wires (MWs) are among the key components in the rising field of molecular electronics.

MWs form one-dimensional electronic conductors to interconnect molecular devices.

Tour said that the team has proved that the "mechanisms of molecular switches are consistent. The molecules tilt back and forth."

As of now, molecular switches are not used for anything, Weiss said. They are still learning how they work and stabilizing them, but they cannot apply them to anything yet.

"They have only been tested in the laboratory," he said. "We do not yet know how to connect them to the nanoscopic, to the microscopic, nor to the macroscopic worlds."

Weiss has been involved in this research for about a decade.