Structural, third-order optical nonlinearities and figures of merit of (E)-1-(3-substituted phenyl)-3-(4-fluorophenyl) prop-2-en-1-one under CW regime: New chalcone derivatives for optical limiting applications

Abstract

In the present work, the crystal structures and third-order nonlinear optical (NLO) properties of two novel chalcone derivatives, (E)-1-(3-bromophenyl)-3-(4-fluorophenyl) prop-2-en-1-one (F3BC) and (E)-1-(3-nitrophenyl)-3-(4-fluorophenyl) prop-2-en-1-one (F3NC) have been experimentally investigated. Both chalcones were synthesized by Claisen–Schmidt condensation reaction. The single-crystals were obtained from slow evaporation solution growth method and were structurally characterized by single-crystal X-ray diffraction. Both studied crystals are crystallized in centrosymmetric space groups. The existence of CH⋯π interactions in F3BC and CH⋯O and CH⋯F hydrogen interactions in F3NC play important roles in creating supramolecular structures. The linear optical absorption coefficient (α) of F3BC and F3NC were analyzed by UV–Vis–NIR spectral analysis and the optical band gaps (Eg) were estimated. TG-DTA analysis revealed that the F3NC crystal has higher thermal stability than F3BC crystal. The third-order nonlinear optical properties of these crystals were studied in solution using Z-scan technique with a continuous wave (CW) DPSS laser operating at 532 nm wavelength. The molecules reveal a strong third-order nonlinear absorption (NLA) and negative nonlinear refraction (NLR). The calculated values of nonlinear absorption coefficient β, nonlinear refraction coefficient n2 and third-order nonlinear susceptibility χ(3) were found to be of the order of 10−5 cm/W, 10−8 cm2/W and 10−6 esu, respectively. The value of the two-photon absorption (2 PA) cross section at 532 nm for both chalcones is of the order of 108 GM. These crystals also exhibited optical limiting (OL) properties under CW laser excitation.