Experimental and DFT studies on a new phase matchable NLO material (1E,4E)-1-(4-methoxyphenyl)-5-phenylpenta-1,4-dien-3-one

摘要

A new promising NLO chalcone (1E, 4E)-1-(4-methoxyphenyl)-5-phenylpenta-1,4-dien-3-one (V_3) has been synthesized by Claisen-Schmidt condensation reaction and was characterized by elemental analysis, ~1H NMR and FTIR techniques. Linear optical study reveals that the material is transparent in the entire visible region with lower optical cut-off wavelength 448 nm and has optical band gap of 2.73eV (Tauc's plot). The TG /DTA study reveals that the title compound melts at 94°C. The second harmonic generation conversion efficiency of the powder sample of V3 was measured using Kurtz powder technique which was found to be 1.28 times greater than that of standard Urea. The particle size dependence of SHG intensity reveals that the V3 is a phase matchable material. Laser damage threshold for the compound was measured to be greater than 0.2 GW/cm~2. Theoretical calculations were performed using Gaussian 03 by adopting B3LYP/6-31G (d) level of theory to derive the molecular first hyperpolarizability (β) and frontier molecular orbitals. Intramolecular charge transfer (ICT) in the molecule is due to HOMO-LUMO interactions which clearly indicate that compound belongs to D-π-A push-pull system. Maximum absorption peak observed in electronic spectra at 368nm (TDDFT) can be assigned to n- π~* transition and is assigned to the excitation of C=O group. Owing to large SHG, phase matchable property and good optical transparency, V_3 can be used for NLO applications.