High-generation second-order nonlinear optical (NLO) Dendrimers that contain isolation chromophores: convenient synthesis by using click chemistry and their increased NLO effects

Herein, high-generation dendrimers G4-NS and G5-NS, which contained 30 and 62 azo-benzene chromophore moieties, respectively, were conveniently prepared in high purity and satisfied yields by a combination of divergent and convergent approaches, coupled with the utilization of the powerful Sharpless click reaction. These dendrimers possessed a regular structure of alternating layers of nitro-based and sulfonyl-based azo chromophores in which the sulfonyl-based azo-chromophore moieties were utilized as co-isolation groups for the nitro-based moieties to achieve larger macroscopic second-order nonlinear optical (NLO) effects. These high-generation dendrimers (G4-NS and G5-NS) displayed very large NLO efficiencies (up to 253.0 pm V(-1)), which is, to the best of our knowledge, the record highest efficiency for simple azo-chromophore moieties.