Synthesis, characterization and structure–activity relationship of non-linear optical response of chalcone derivatives with in silico insights

Abstract

Fifteen chalcone derivatives having D–A–D, D–A–A and A–A–D architectures have been synthesized by Claisen–Schmidt condensation reaction and characterized by UV–Vis, IR, 1H-NMR, 13C-NMR and Mass spectrometry. In order to unambiguously establish the structure–activity relationship for the non-linear optical activity of these compounds, for the first time to our knowledge, we use the femtosecond degenerate four wave mixing (DFWM) technique to quantify and compare the third-order non-linear optical (NLO) activity of all the 15 compounds, under identical conditions. The second harmonics generation (SHG) efficiencies for all the compounds have also been evaluated using the Kurtz-Perry powder method. Among the compounds that we have synthesized here, the ones with A–A–D architecture show the highest NLO activity. Our results show that the NLO activity of a compound with A–A–D architecture can be further enhanced by incorporating a substituent with strong electron withdrawing ability on ring A and strong electron donating substituent on ring B. The results of the in silico studies that we have carried out correlate well with our experimental findings. The compounds (E)-3-(4-(dimethylamino)phenyl)-1-(4-nitrophenyl)prop-2-en-1-one with the compound code (4-N(CH3)2–4′-NO2) and (E)-3-(4-methoxyphenyl)-1-(4-nitrophenyl)prop-2-en-1-one with the compound code (4-MeO-4′-NO2) show the highest NLO activity among the compounds we have reported here.