Enhanced nonlinear optics properties of a bromine chalcone from a novel polymorph

A comparative study of structural and spectroscopic properties of three structurally similar mechanically bending organic single crystals - 2-Amino-3-nitro-5-halo (halo = Cl, Br, or I) pyridine

In recent years, scientists have been very interested in single crystals of monoaromatic compounds with mechanical softness, but they are hard to find. The present work reports a comparative study of structural, spectroscopic, and quantum chemical investigations of three structurally similar mechanically bending monoaromatic compounds, namely, 2-amino-3-nitro-5-chloro pyridine (I), 2-amino-3-nitro-5-bromo pyridine (II), and 2-amino-3-nitro-5-iodo pyridine (III). The mechanical responses of the three organic crystals studied here are very intriguing due to the similarity of their chemical structures, which only differ in the presence of halogen atoms (Cl, Br, and I) at the fifth position of the pyridine ring and are explained through examining intermolecular interaction energies from energy frameworks analysis, slip layer topology, and Hirshfeld surface analysis. The crystals of all the three feature one dimensional ribbons comprising alternating NaminoH⋯Onitro and NaminoH⋯Npyridine hydrogen bonds that form R22(12) and R22(8) dimeric rings, respectively. In (III), weak I⋯I interactions link the adjacent ribbons forming a two dimensional sheet. Layer-like structures are observed in all three crystals, with no significant interactions between the adjacent architectures (ribbons or sheets). Energy framework calculations are used for estimating the bending ability of the three compounds, with the three following the order Cl ≪ Br < I. The iterative electrostatic scheme coupled with the supermolecule approach (SM) at the DFT/CAM-B3LYP/aug-cc-pVTZ level is used to calculate the third-order nonlinear susceptibility (χ3) values in a simulated crystalline environment for the static case as well as two typical electric field frequency values, (λ = 1064 nm) and (λ = 532 nm). In addition, estimates of the topological studies (localized orbital locator and electron localization function) and reactivity characteristics (global reactivity parameters, molecular electrostatic potential, and Fukui function) are made for the compounds under investigation. Docking studies done using AutoDock software with a protein target (PDB ID: 6CM4) revealed that three compounds could be used to treat Alzheimer's disease.

Synthesis and structural studies on (E)-3-(2,6-difluorophenyl)-1-(4-fluorophenyl)prop-2-en-1-one: a promising nonlinear optical material

A new fluorinated chalcone (E)-3-(2,6-difluorophenyl)-1-(4-fluorophenyl)prop-2-en-1-one was synthesized in 90% yield and crystallized by a slow evaporation technique. Its full structural characterization and purity were determined by scanning electron microscopy, infrared spectroscopy, gas chromatography-mass spectrometry, 1H, 13C and 19F nuclear magnetic resonance, thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), Raman microspectroscopy, UV-Vis absorption spectroscopy, single crystal X-ray diffraction (XRD) and Hirshfeld surface (HS) analysis. The fluorinated chalcone crystallized in centrosymmetric space group P21/c stabilized by the C-H⋯O and C-H⋯F interactions and the π⋯π contact. The crystalline environment was simulated through the supermolecule approach where a bulk with 378 000 atoms was built. The electric parameters were calculated at the DFT/CAM-B3LYP/6-311++G(d,p) level as function of the electric field frequency. The macroscopic parameters such as linear refractive index and third-order nonlinear susceptibility (χ (3)) were calculated, and the results were compared with experimental data obtained from the literature. The χ (3)-value for the chalcone crystal is 369.294 × 10-22 m2 V-2, higher than those obtained from a few similar types of molecule, showing that the chalcone crystal can be considered as a nonlinear optical material. Also, molecular theoretical calculations such as infrared spectrum assignments, frontier molecular orbital analysis and MEP were implemented, revealing that the most positive region is around the hydrogen atoms of the aromatic rings, and electrophilic attack occurs on the carbonyl group.