Some things work better together—synergy between different types of catalytic sites is a coveted goal, often leading to improved bimetallic catalysts with interesting properties.

U. Hanefeld, Technische Universiteit Delft (TUD), The Netherlands, and colleagues have reported the synergistic catalytic properties of three-dimensional amorphous mesophorus materials containing aluminium and zirconium. The bimetallic materials, named Al-Zr-TUD-1, were synthesized in a surfactant-free, one-pot procedure employing triethanolamine as the complexing agent.

The catalyst performed particularly well in enhancing the rate of activity of the intermolecular Prins cyclisation of citronellal (below). The catalyst contains both Lewis and Brønsted acid sites in close proximity, so it can activate both the alkene and carbonyl reacting groups. Although Al-Zr-TUD-1 catalysts possess lower amounts of acid sites than their monometallic counterparts, the material was superior in its catalytic ability, proving its synergistic properties.

Images: (c) Wiley-VCH

• On the Synergistic Catalytic Properties of Bimetallic Mesoporous Materials Containing Aluminum and Zirconium: The Prins Cyclisation of Citronellal
  S. Telalović, A. Ramanathan, J. F. Ng, R. Maheswari, C. Kwakernaak, F. Soulimani, H. C. Brouwer, G. K. Chuah, B. M. Weckhuysen, U. Hanefeld,
  Chem. Eur. J. 2011, 17(7), 2077-2088.
  DOI: 10.1002/chem.201002909