New Coumarin-benzoxazole derivatives: Synthesis, photophysical and NLO properties

In this work, a series of novel D-π-A structure coumarin-benzoxazole derivatives have been synthesized. The third-order NLO properties of the coumarin derivatives in DMSO are investigated by Z-scan measurement, and the photophysical properties of the compounds are studied through experimental and theoretical calculation methods. The results showed that the introducing specific functional groups at multiple active sites of coumarin reduced the π-π intermolecular stacking, while the formation of push-pull structure decreased E-gap of entire molecule. The excellent third-order NLO responses based on chromophore 4c with maximum nonlinear absorptive coefficients is 50.64 × 10−13 esu and the largest second-order NLO hyperpolarizability is 7.12 × 10−30 esu. Experimental results have also been confirmed through DFT, TDDFT and ZINDO calculations. Our results indicate that the coumarin fluorescent dyes are promising candidate materials for NLO applications.