Structural Characterization, Theoretical Investigation and Hirshfeld Surface Analysis of 2,6-(E,E)-bis((thiophene-2-yl)methylene)cyclohexanone

Abstract

The bis(chalcone) compound, 2,6-(E,E)-bis((thiophene-2-yl)methylene)cyclohexanone, has been synthesized and characterized by FTIR, 1H-NMR, 13C-NMR techniques, X-ray structure analysis. The optimized molecular structure of the studied compound is calculated using DFT/B3LYP with 6-31G (d,p) level. The calculated geometrical parameters are in good agreement with the experimental data obtained from our reported X-ray structure. The calculated IR fundamental bands, 1H and 13C NMR chemical shifts of the compound were assigned and compared with the experimental data. Additionally, frontier molecular orbital energies (HOMO, LUMO), their energy gap (, molecular electrostatic potential analysis of the compound have been calculated by the same method. The molecular electrostatic potential (MEP) was used to visualize the charge distribution on the molecule. In addition, the intercontacts in the crystal structure are analyzed using Hirshfeld surfaces computational method. The title compound (C16H14OS2) crystallizes in the monoclinic chiral space group P21/c with a=15.0492(10)Å, b=12.0085(9)Å, c=7.6283(6) Å, β=95.883(7)o, V=1371.31(17)Å3, Dcalc=1.387g/cm3. The central cyclohexanone ring has a flattened chair conformation and the substituents at the vinyl group of each chalcone moiety exhibit a trans (entgegen) disposition, and the two thiophene rings adopt a syn orientation and are located on the both side of the cyclohexanone. The asymmetric unit of the title compound, C16H14OS2, contains one-half of a molecule. The other half of the molecule is generated with (x,y,-z) symmetry operator. In the molecule there are two weak C-H…S and C-H…O intramolecular and only C-H…O intermolecular hydrogen bonds. In addition, π…π interactions are found in the crystal structure between the thiophene rings.