TOWARD MODULAR CHEMISTRY WITH THE DENDRITIC BOX AS MODULE

摘要

In this paper we like to present the dendritic box as a new tool toward modular chemistry. A dendritic structure with a densely-packed shell is prepared via modification of the fifth generation poly(propylene imine) dendrimers with N-BOC-L-phenylalanine groups. This so-called dendritic box has a diameter of approximately 4.5 nm, as determined by DLS and SAXS, and has internal cavities which can be used for the encapsulation of guest molecules. Supramolecular encapsulation is achieved by performing the construction of the box in the presence of the guest molecules, followed by dialysis to remove excess and adhered guest. A number of properties of encapsulated guests is critically influenced by the host, like the observation of induced optically activity and a solvent-independent fluorescence of dyes encapsulated as well as the formation of a triplet radical pair of 3-carboxy-proxyl. A shape-selective liberation of encapsulated guests is accomplished by a two-step hydrolysis of the shell. The potentials of these boxes as new supramolecular architectures within the nanometer regime are discussed and the physical locking of guest molecules is proposed as a new binding principle useful for modular chemistry.