Comparing two-photon absorption of chalcone, dibenzylideneacetone and thiosemicarbazone derivatives

We compared the experimental nonlinear optical responses (NLO) of one chalcone (BCH-1), two dibenzylide-neacetone (BCH-2 and BCH-3), and two thiosemicarbazones dibenzylideneacetone (TSCD-1 and-2). The com-pounds were synthesized by the Claisen-Schmidt reaction and characterized using NMR, FTIR, and UV-Vis. The Z-scan technique, using femtosecond pulses, obtained two-photon absorption cross-section (cr2PA) spectra of the investigated compounds, which presented moderate values of cr2PA, ranging from 28 GM to 69 GM. Such cr2PA difference in the NLO response is usually associated with the length of the conjugated chain and the different functional groups used. For example, increasing the conjugated x-chain and peripherals groups from BCH-1 to BCH-2 led to a doubling effect on the magnitude of the NLO (cr2PABCH_1 = 28 GM, cr2PABCH_2 = 64 GM). A noticeable drop in the NLO response is observed from cr2PABCH_2 = 64 GMto cr2PABCH_3 = 39 GMdue to the replacement of the 3,4,5 tri-methoxyphenyl by the thiophene aromatic peripheral group, respectively. The higher NLO response is attributed to compounds TSCD-1 and-2, with values of about 69 GM and 66 GM, respectively, indicating that bromo-and chloro-substituents do not influence the NLO response. According to the obtained results and considering the investigated compounds' short pi-chain, we could claim that these classes of organic molecules are promising NLO materials.

Automated summary

The NLO response of the investigated compounds is mainly determined by the length of the conjugated chain and the different functional groups. The replacement of the aromatic peripherals and the presence of bromo- and chloro-substituents do not greatly influence the NLO response.