First principles study for the key electronic, optical and nonlinear optical properties of novel donor-acceptor chalcones.

Using first-principle methods, several key electronic, optical and nonlinear optical properties are calculated for two recently synthesized chalcone derivatives i.e. (2E)-3-(4-methylphenyl)-1-(3-nitrophenyl)prop-2-en-1-one (comp. 1 ) and (2E)-3-[4-(dimethylamino)phenyl]-1-(3-nitrophenyl)prop-2-en-1-one (comp. 2 ). The calculation of dipole moment, polarizability <α>, anisotropy of polarizability as well as second hyperpolarizability (usually considered as a signature for two photon absorption phenomenon) are performed using density functional theory methods at PBE0/6-311G** level of theory. The linear average polarizability <α> for comp. 1 and comp. 2 are found to be 32.15 × 10 −24 and 38.76 × 10 −24 esu, respectively. Similarly, the second hyperpolarizability <γ> amplitudes of comp. 1 and comp. 2 are found to be reasonably larger mounting to 79.31 × 10 −36 and 181.36 × 10 −36 esu, respectively. The importance of donor end is determined by comparing p -methylphenyl group of comp. 1 with that of N , N -dimethylaniline group of comp. 2 that results a remarkable increase in its <γ> amplitude, which is ∼2 times larger as compared with that of comp. 1 owing to the stronger donor-acceptor configuration of comp. 2 . Interestingly, a comparison of average static third-order nonlinear polarizabilities <γ> shows that <γ> amplitudes of comp. 1 and comp. 2 are ∼13 times and ∼29 times larger than that of para -nitroaniline (a typical standard push-pull NLO-phore) at the same PBE0/6-311G** level of theory, which indicates a real time NLO application of our titled compounds. Time dependent density functional theory (TD-DFT) calculations along with frontier molecular orbitals, density of states (DOS), second hyperpolarizability density analysis and molecular electrostatic potential (MEP) diagrams are used to trace the origin of electro-optical as well as structure property relationships. [ABSTRACT FROM AUTHOR]