The reaction studied was a classical Diels-Alder reaction that was promoted by applying an oriented electric field between two nano-electrodes containing the reacting molecules.
“Theory suggested that many chemical reactions – and not just redox (electron transferring) reactions, as is often thought – might be catalysed by applying an electric field,” says Ismael Díez-Pérez, assistant professor at the UB and senior researcher at IBEC, who led the study published in Nature today. “We’ve provided experimental evidence for this for the first time.”
Being able to catalyse chemical reactions is essential, as it speeds up the reaction and thus makes it more proliferate – and therefore cheaper to use – in its many applications. Electrostatic catalysis (the use of electric fields) is the least developed form of catalysis in synthetic chemistry, because electrostatic effects are strongly directional. The researchers in Spain and Australia overcame this by using state-of-the-art single molecule techniques that are based on scanning tunnelling microscopy.
“Our modified STM approach allows recording direct signatures of individual molecules reacting”, says Albert C. Aragonès, a FPU-PhD student at IBEC and UB and first author on the study.
“By controlling the orientation of the molecules with respect to the electric field, we accelerated a non-redox reaction for the first time,” adds Ismael.
“Using external electric fields as the ‘catalyst’ in this way means that the synthesis of molecules that otherwise might not occur in a feasible way in laboratories or large industrial facilities can be achieved”, adds Nadim Darwish, a Marie Curie Research Fellow at IBEC and UB. “This opens the door for future chemical technology.”
Source paper: Albert C. Aragonès, Naomi L. Haworth, Nadim Darwish, Simone Ciampi, Nathaniel J. Bloomfield, Gordon G. Wallace, Ismael Diez-Perez & Michelle L. Coote (2016). Electrostatic catalysis of a Diels–Alder reaction, Nature