Novel global-like second-order nonlinear optical dendrimers: convenient synthesis through powerful click chemistry and large NLO effects achieved by using simple azo chromophore

In this paper, global-like dendrimers, G1-TPA, G2-TPA and G3-TPA, bearing 9, 21 and 45 azobenzene chromophore moieties, respectively, were conveniently prepared with high purity and satisfactory yields, through the combination of divergent and convergent approaches, coupled with the utilization of the powerful Sharpless "click" reaction. Due to their perfect 3D structure and the isolation effect of the exterior benzene moieties and the interior triazole rings, these global-like dendrimers exhibited large d(33) (a second harmonic generation coefficient) values, e. g., 246.0 pm V-1 for G3-TPA, which, to the best of our knowledge, is a new record reported so far for simple azo chromophore moieties.