Highly Emissive Supramolecular Oligo(p-phenylene vinylene) Dendrimers

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Abstract
π-Conjugated oligo(p-phenylene vinylene) (OPV) guest molecules for interaction with dendritic hosts were synthesized and fully characterized by NMR spectroscopy, MALDI-TOF−MS, elemental analysis and optical measurements. The binding properties of the five different OPV guests to a N,N-bis[(3-adamantyl ureido) propyl] methylamine host have been investigated. The guests that contained an aryl urea glycine spacer were bound with the highest association constant. Subsequently, an adamantyl urea modified fifth generation poly(propylene imine) dendrimer was synthesized as a multivalent host which contains 32 N,N-bis[(3-adamantyl ureido) propyl] amine binding sites. Size exclusion chromatography showed that 32 of the OPV guests strongly bind to the fifth generation adamantyl functionalized dendritic host. In the case of the supramolecular dendritic host/guest system smooth homogeneous thin films could be obtained by spin coating. The dendritic guest−host complexes showed a significantly higher emission upon binding then that of the individual molecules due to the three-dimensional orientation of the OPV guest molecules. In the solid state, this enhancement in luminescence was a factor of 10. The π-conjugated oligomers are less aggregated in the supramolecular assemblies presumably because of a shielding effect of the bulky adamantyl units present in the hosts.