A novel carbosilane dendrimer that can tell the difference between the enantiomers of an amino acid analogue may lead to new organocatalysts and resolving agents. 

Dendrimers consist of a core molecule to which monomer branches are attached at several points. The resulting molecule is a first generation dendrimer. If further monomers are added to the newly-formed dendrimer then a second generation dendrimer is formed, and so on. The overall compound resembles the top of a tree, the branches of which are called dendritic wedges or dendrons. 

Dendrimers are of interest as potential drug delivery agents because they can be bound to other molecules or guests, offering stability in conditions where the guest would otherwise deteriorate. Carbosilane dendrimers, so-called because they are composed mainly of carbon and silicon, form a versatile range of these polymers. 

Joost Reek and co-workers at the University of Amsterdam, the Netherlands, used a technique called convergent dendrimer synthesis to prepare the branches of a carbosilane dendrimer before joining them to its core. Reek's approach led to dendrimers previously difficult to obtain that were capable of recognizing guest molecules. 

The physical properties of carbosilane dendrimers can be tuned by varying the monomers used or by attaching different groups to the outer surface, but until now very little research has focused on modifications to the core of these dendrimers. This new line of enquiry has already led to the synthesis of important new dendrimers and may be of interest for the fields of organocatalysts and resolution chemistry, says Reek.  

Celia A Clarke