Abstract
Herein, we report linear polarizibilty (α) and hyperpolarizibility (β) of anthracyl-based organic materials containing electron acceptor (NO2) and electron donor (NH2) moieties. Six compounds (a–f) were designed by structural modification of a reported chromophore 9,10-bis(phenylethynyl)anthracene (R). Ground state geometries, HOMO-LUMO energies polarizability, first hyperpolarizability and natural bond orbital (NBO) analyses of all compounds (R and a–f) were studied through density functional theory. FMO's results showed that the energy gaps of designed molecules a–f (1.791–2.215eV) were much lower than parent molecule R (2.606 eV). UV Visible analysis of designed compounds showed a red shift in the absorption spectrum as compared with reference molecule (R). The highest λmax was observed for compound c (816.7 nm). NLO analysis and hyper polarizibility values computed for compounds a-f were much higher than reference compound R (0.023 a.u.). The observed red shifts in the absorption spectra indicated the decrease in excitation energy, an important factor in enhancing NLO response. Overall, compound c showed larger αtotal and βtotal values of 575.9 a.u. (LC-BLYP/6–31++G(d,p), and 58156.8 a.u. (LC-BLYP/6–31++G(d,p), respectively. The findings of our study provide a theoretical platform for useful conversion of centrosymmetric compounds to non-centrosymmetric materials for enhancing the NLO behavior through structural modifications for modern technological applications.
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