For Mark Reed, the future of molecular electronics has just arrived. A self-described "device guy," Reed, who heads Yale University's electrical engineering department, prides himself on having a distinctly practical bent. Ask him about the possibility of one day using molecules to replace silicon in computers that are billions of times faster than today's PCs or that fit on the head of a pin, and he grimaces. "I don't know how to do that. I don't think anyone does," he says dismissively.

But that doesn't dim the excitement that Reed, a leading researcher in molecular electronics, is feeling. Using molecules synthesized by Rice University chemist James Tour, Reed has fabricated electronic memories and a simple logic element made up of molecules that function as tiny, individual switches. The devices, which rely on small organic molecules tailored by the Rice chemists to have just the right electronic properties, are crude laboratory experiments. But they work-the molecules acting as a component in ultrasmall electronic devices able to turn current "on" and "off." What's more, these early prototypes have already shown hints of performing memory and logic tricks not possible with silicon semiconductors.