Efficient synthetic routes to hitherto unknown core-trisubstituted naphthalene diimides (NDIs) starting with 2,6-dichloro-substituted NDIs 1 are described. The reaction of NDIs 1 with ethylene diamine as solvent, affords the ethylene-diamine-bridged core-trisubstituted NDIs 2 in very good yield. The substitution of the chlorine atom of 2 with alkylamino or alkoxy nucleophiles leads to triamino- or alkoxy-diamino-substituted NDIs. UV/Vis spectroscopy revealed that the electronic properties of NDI chromophores bearing three core substituents are strongly influenced by the nature of the substituents. NDIs which are tri(alkylamino)-substituted at the naphthalene core exhibit high (up to 70%) fluorescence quantum yields.
dyes - fluorophores - rylenes - nucleophilic aromatic substitution - intramolecular ring closure
