Dendrimer noncovalently functionalized

Whether dendritic catalysis can compete successfully in commercial applications with other strategies that allow recycling of the catalyst remains to be seen. Dendrimer supports are still relatively expensive, but for applications that do not require the well-defined structure of the dendrimer support, hy-perbranched polymers can offer a cheaper alternative. A recent novel strategy in this research area that might provide the added value required to make the step towards commercial applications involves the noncovalent functionalization of dendritic support with catalysts (Fig. 1). This offers several advantages above the traditional covalent approaches. In this chapter we will review the progress in the area of supramolecular dendritic catalysis. 

Noncovalently Functionalized Dendrimers Based on Multiple Interactions... 

Fig. 5 The application of a noncovalently functionalized dendrimer (1) in a CFMR in the allylic animation of crotyl acetate and piperidine in dichloromethane (Koch MPF-60 NF membrane, molecular weight cut-off = 400 Da). The crossed square represents the yield expected on the basis of the retention factor of the system and the deviation is explained by catalyst decomposition...

Kainz, Q. M., A. Schatz, A. Zbpfl, W. 1. Stark, and O. Reiser. Combined covalent and noncovalent functionalization of nanomagnetic carbon surfaces with dendrimers and BODIPY fluorescent dye. Chem. Mater. 23, 2011 3606-3613. 

Ribaudo F, van Leeuwen PWNM, Reek JNH (2006) Supramolecular Dendritic Catalysis Noncovalent Catalyst Anchoring to Fimctionalized Dendrimers. 20 39-59 Richmond TG (1999) Metal Reagents for Activation and Functionalization of Carbon-Fluorine Bonds. 3 243-269... 

The groups of Reek and Meijer have also applied the noncovalent approach for catalyst anchoring to a dendrimer support [62], Phosphine functionalized ligands were attached to the periphery of polypropylene imine) dendrimers via combined ionic interactions and H-bonding using a specific binding motif that is complementary to that of the support (Fig. 6). 

Fig. 4 The first supramolecular dendritic catalyst in which 32 phosphine ligands are noncovalently anchored to the functionalized dendrimer by hydrogen bonds and ionic interactions...

Recently, we extended the approach to dendrimers immobilized on silica. For this purpose, the first generation (and also larger generations) DAB den-drimer was functionalized with urea propyl-(SiOR)3 groups that via an easy process were grafted on silica. The catalyst was noncovalently anchored by simply adding a solution of a metal complex with ancillary ligands utilized with the typical the complementary motif (Fig. 7) [29]. 

Supramolecular Dendritic Catalysis Noncovalent Catalyst Anchoring to Functionalized Dendrimers... 

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