Dendritic hosts guest encapsulation

The possibilities for encapsulating guest molecules in dendritic hosts were first proposed by Maciejewski in 1982 [143], In 1990, Tomalia presented evidence for unimolecular encapsulation of guest molecules in dendrimers and pointed out that it was one of the possible future research areas in dendrimer chemistry [164],... 

This chapter presents a selective glimpse of this dynamic family of spherical macromolecnles for newcomers to the topic in order to help them better appreciate the field that has been extensively reviewed elsewhere. This chapter is divided into several parts to emphasize the structmal diversity and their potential applications. First, a study of the internal structure of the dendritic architecture, emphasizing the different types, followed by a study of their interactions with other molecules or atoms, such as in the case of host-guest chemistry, molecular recognition, or encapsulation inside the dendrimer. Finally, there is a small section that will address the intermolecular interactions of dendrimers and dendrons to either themselves or other nano-objects. In this past quarter century, tens of thousands of papers have been published producing a wide variety of different dendritic architectures with varied structural components capable of novel supramolecular interactions. Therefore, only an overview describing their structure with representative examples and practical purposes will be discussed, when appropriate. 

Dendrimers and dendrons are appealing types of nanoscale, highly branched, macromolecules, which, because of their structure and properties, have attracted the interest of many researches worldwide. The preceding text has tried to summarize the different selective supramolecular aspects about their properties, structure, potential diversity, and applications to nonspecialized scientists. An introduction of these dendritic structures has combined a short description of the structure and synthesis with some historical perspectives, followed by a classification of dendritic structures, as covalent and noncovalent entities. Emphases have been given to their host-guest capacity to encapsulate small molecules, ions, or nanoparticles, as well as to interact with themselves or other nano-objects. The continued investigation in many fields of these unique architectures has produced a wide variety of branched fractal constructs, which undoubtedly will continue to spark the imagination of future synthetic architects. 

Rose Bengal and 8-10 molecules of p-nitrobenzoic acid could be encapsulated in each dendritic host. To achieve selective liberation of p-nitrobenzoic acid, the dendritic box was penetrated by hydrolysis of the iBOC and dialysis of the reaction mixture. In this way aU p-nitrobenzoic acids were dissolved in the mixture while guests Rose Bengal remained encapsulated. Hydrolysis of the outer shell released Rose Bengal after dialysis [25],... 

The amidoferrocenyl or silylferrocenyl monomers do not show any effect, however. Therefore, the dendrimer topology is important for recognition of oxo-anions. The appropriate encapsulation of the anionic host between the dendritic tethers is a key factor that very much increases the interaction between the functional ferrocenyl termini and the guest (Scheme 8.6). 

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