Synthesis, characterization and nonlinear optical properties of symmetrically substituted dibenzylideneacetone derivatives

Nonlinear Optical Study in a Set of Dibenzylideneacetone Derivatives with Potential for Optical Frequency Conversion

The search for advanced optical materials, in particular, materials with nonlinear optical responses, has, in the last years, experienced substantial growth due to their vast applications in the photonics field. One of those applications is ultra-fast optical frequency conversion, in the optics communications field. Organic compounds have emerged as promising candidates for raw materials to develop nonlinear optical devices, such as optical converters, due to their intrinsic ultra-fast electronic responses. Also, the easy tailoring of organic molecular structures makes organic materials much more appealing than the inorganic ones. In this work, we have performed a linear and nonlinear optical characterization of a set of dibenzylideneacetone derivatives. The nonlinear optical responses investigated correspond to second- and third-order nonlinear processes, namely, first electronic molecular hyperpolarizability and two-photon absorption cross-section, respectively. The value of the first electronic molecular hyperpolarizability, up to 52 cm4·statvolt−1, could be considered a robust value when compared to the short-sized π-electron backbone length of the studied compounds. Such results suggest that these compounds exhibit the potential to be used as optical frequency converters. Quantum chemical calculations were used to predict the theoretical value of the first molecular hyperpolarizability, as well as to simulate the one- and two-photon absorption spectra for all compounds.

Synthesis of diarylidenecyclohexanone derivatives as potential anti-inflammatory leads against COX-2/mPGES1 and 5-LOX

This study establishes the diarylidenecyclohexanones as good anti-inflammatory pharmacophores with selective high potency against PGE₂and 5-LOX without toxicity towards healthy human cells.

Crystal growth and characterization of second- and third-order nonlinear optical chalcone derivative: (2E)-3-(5-bromo-2-thienyl)-1-(4-nitrophenyl)prop-2-en-1-one

Experimental and computational studies of linear and nonlinear optical (NLO) properties of (2E)-3-(5-bromo-2-thienyl)-1-(4-nitrophenyl)prop-2-en-1-one (5B2SNC) single crystals are reported. Good-quality and large-sized single crystals of 5B2SNC were successfully grown and characterized by powder X-ray diffraction and high-resolution X-ray diffractometry techniques. 5B2SNC was found to crystallize in the monoclinic noncentrosymmetric space group Cc and possesses moderately good crystalline perfection. The linear optical properties were investigated using the absorption spectrum, which reveals a direct optical band gap of 3.1 eV. The thermal stability was studied with thermogravimetric analysis/differential thermal analysis. The powder second harmonic generation efficiency was evaluated by the Kurtz and Perry method, and 5B2SNC was found to be 26 times more efficient than urea standard. Third-order NLO properties were studied by the z-scan technique with a femtosecond laser. The second hyperpolarizability was obtained to be ∼1.45 × 10−31 e.s.u. The molecule reveals a strong reverse saturation absorption and negative nonlinear refraction. The molecule exhibited good optical limiting properties, and its limiting threshold was measured to be ∼3.2 mJ cm−2. In addition, static electric dipole moments, linear polarizabilities, and first- and second-order hyperpolarizabilities were calculated by density functional theory (DFT). Highest occupied molecular orbital/lowest unoccupied molecular orbital band gaps were also evaluated by DFT calculations. The experimental and theoretical results showed that 5B2SNC exhibits excellent second- and third-order nonlinear optical properties.

Highly enantioselective asymmetric Henry reaction catalyzed by novel chiral phase transfer catalysts derived from cinchona alkaloids

Newly synthesized CPTCs are applied in the asymmetric Henry reaction to a wide range of aldehydes under mild reaction conditions, and we obtained higher chemical yields and an excellent enantiomeric excess.