Supramolecular Dendrimer Chemistry: A Journey Through the Branched Architecture

Abstract

The three-dimensional branched architecture of a dendrimer consists of three topologically distinct regions: multivalent surface, branching repeat and encapsulated core. This paper discusses the use of dendritic architectures for supramolecular chemistry and, in particular, focuses on the unique ability of the branched shell to affect molecular recognition processes in these three regions. The multivalent nature of the fractal dendrimer surface allows the recognition of multiple guests with maximum efficiency and accessibility. Such multivalent recognition has been used both to enhance binding strengths for weak molecular recognition processes, and also to endow the receptor with much improved guest sensing properties.With the site of recognition in the branched repeat unit, dendritic hosts can exhibit not only high guest uptake, but also interesting cooperative binding effects. Meanwhile, recognition sites buried at the core experience the unique microenvironment generated by the dendritic branching. This microenvironment can generate new modes of binding and hence novel guest selectivities. As a consequence, such host molecules can mimic aspects of biological behaviour, particularly that of enzymes. Well-defined molecular recognition events with dendritic molecules also provide an entry into more highly organised supramolecular constructions and assemblies. This paper provides a survey of dendritic molecular recognition processes and, in particular, highlights the different ways in which the branched shell can actively control the binding event.