Six-branched chromophores with isolation groups: synthesis and enhanced optical nonlinearity

Abstract

Three new six-branched chromophores with different isolation groups were designed and synthesized by incorporating azo chromophores onto phenyl glycerol ester via an esterification reaction. The chemical structures were confirmed by ¹H NMR, ¹³C NMR, FT-IR spectroscopy, mass spectrometry, element analysis and UV-visible absorption spectra. The six-branched dendritic chromophores can form thin films directly without adding any polymer matrix and show a quite high chromophore loading density. After electric poling, the nonlinear optical coefficients (d₃₃) of the dendrimer films were determined to be around 113, 142 and 136 pm V⁻¹, which are almost 3 times the maximum d₃₃ value of the azo-chromophore doped polymer films. The further improvement in optical nonlinearity was successfully realized by mixing the six-branched chromophores containing different isolation groups.