Assessing the dipolar-octupolar NLO behavior of substituted thiosemicarbazone assemblies

Density Functional Theory with hyper-Rayleigh scattering is used to investigate the non-linear optical response of newly synthesized thiosemicarbazone molecules. The systems present low refractive indices, and PDOS analyses indicate that the substituents chlorine and bromine induce a batchromism in the UV-Vis spectra and significantly improve (ca. 69%) the estimate of the first hyperpolarizability (??????HRS) to values fifty times higher than those reported for urea (?????? = 0.34 x 10-30 esu). Moreover, intramolecular charge transfer processes and evident octupolar contributions (???????????? =3 approximate to 70%) account for the NLO behavior. The results suggest potential uses in optoelectronics and photonics.