Using a chain of molecules as an infinitesimal lanyard to tug on a chemical bond about to break, Duke University chemists have found they can speed a complex chemical reaction Craig's group used an AFM tip to exert almost infinitesimally small tugs on a molecular complex made of pyridine and the metal palladium.
The researchers dangled the pyridine-palladium complex in space as if it were part of a molecular trapeze act, by attaching trapeze "wires" made of atomic chains of the molecule polyethylene glycol (PEG). One PEG chain connected the dangling pyridine-palladium to the AFM's tip. A separate PEG "wire" anchored the complex underneath onto an underlying surface substrate.
When the AFM's flexible tip pivoted upward, it pulled on the bond linking the pyridine to the palladium. "This is almost like spring-loading that bond," Craig said.