Dopant Makes Palladium Chiral

Figure 1. Small coin-like disk (left) was pressed from chiral form of palladium. Source: Paul F. Collignon, University of Amersterdam.The team, lead by Gadi Rothenberg, professor of heterogeneous catalysis and sustainable chemistry at the University of Amsterdam, changed the structure of palladium by doping it with a cinchona alkaloid. “…The alkaloid molecules are entrapped between the Pd crystallites, resulting in a three-dimensional metallo-organic hybrid structure that is chiral. The resulting chirally modified metal-organic composites catalyze the asymmetric hydrogenation of aceteophenone and isophorone with significant (albeit moderate) enantiomeric excess. Excitingly, the Pd metal retains its chiral aspect even after extraction of the alkaloid modifier,” they report in Nature Chemistry.The composite material keeps the metal’s usual properties of malleability, conductivity and catalytic activity, and can be pressed into shapes. (Figure 1 shows it formed into a coin-sized disk.) Experiments at Hebrew University of Jerusalem showed that the two chiral forms of palladium provide different catalytic activities for absorption reactions.