Bifunctionalised molecular periphery

Phosphorus-containing surface-block dendrimers can be prepared by a method developed by Majoral et al. [57] (Fig. 3.9). 

Newkome et al. were the first to present a combinatorial approach to the synthesis of peripherally heterogeneously functionalised POPAM dendrimers of type B (see Fig. 3.7), which is based on functionalisation of end groups with a 

Kim et al. first reacted dendrimers bearing hydroxy terminal groups with amine-protected a-amino acids after basic cleavage of the protective group they were able to introduce a second functionality by means of carboxylic acids [62]. 

However, these bifunctionalisation methods are comparatively laborious and applicable only in special cases, since the monofunctionalisation step is limited to substrates possessing an additional coupling site in protected form for the second functional unit. A more versatile method of local bifunctionalisation, which has no need of a deprotection step and also utilises commercially available dendrimer scaffolds, consists in the functionalisation of POPAM dendrimers bearing amine terminal groups with sulphonyl chlorides and subsequent substitution of the sulphonamide proton with other sulphonyl chlorides [63] or with alkyl- or (dendritic) benzyl bromides [64] (see Fig. 3.13). 

The preparation of peripherally bifunctionalised dendrimers by the method of non-covalenl local bifunctionalisation has hitherto remained restricted to individual cases. This method of bifunctionalisation can be applied to peripherally 

---

Bifunctionalised dendrimer with perfectly alternating molecular periphery. 

---