New halogenated chalcones: Synthesis, crystal structure, spectroscopic and theoretical analyses for third-order nonlinear optical properties

The halogen chalcones have been prepared by a simple condensation reaction of 4-bromoacetophenone with different substituted halogen benzaldehydes by presence of catalyst of sodium hydroxide. The proposed structures were solved and refined by single crystal X-ray diffraction analysis and the optimized molecular structure at the ground state were further performed using density functional theory (DFT) method with B3LYP/6-311G++(d,p) basis set level. The supramolecular C-H center dot center dot center dot O, C-H center dot center dot center dot Cl and C-H center dot center dot center dot pi hydrogen bonds and halogen center dot center dot center dot halogen interactions observed stabilize and strengthen the crystal structure of the halogen chalcones. All the newly synthesized compounds were characterized by spectroscopic methods including, FT-IR, H-1 and C-13 NMR and UV-Visible. The experimental geometrical parameters were compared with the calculated TD-DFT, where the values are in good agreement. All compounds exhibiting a good HOMO-LUMO energy gap values in a range of 4.0 and 4.2 eV. Additionally, Hirshfeld surfaces analysis was used to quantify the intermolecular interactions and to analyze inter-contacts in the crystal structure. Results revealed mono-substitution molecules with ortho position will give a high impact on electronic dipole moment, thus offering a better quality NLO properties of the compounds. (C) 2019 Elsevier B.V. All rights reserved.