Structure and theoretical approaches to a chalcone derivative

Chalcones are α,β-unsaturated aromatic ketones which can present a wide range of biological activities. Here, the structure of the chalcone ( E )-1-(4-biphenyl)-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one was determined by single crystal X-ray diffraction technique and compared to those of similar compounds whose crystal structures are available in the Cambridge Structural Database. These comparisons have allowed us to conclude that electron delocalization is abrogated through the biphenyl and carbonyl moieties, while resonance effects are increased through the trimethoxyphenyl group and the olefin carbons. Single-molecule calculations of the asymmetric unit using the DFT method have strengthened these structural relationships, since experimental and theoretical molecular geometries were similar. For instance, the global minimum for the optimized structure occurs when one of the four dihedral angles on the bridge between the two rings of biphenyl is 40.25°, a value close to that of the corresponding torsion determined by single crystal X-ray diffraction analysis [41.7(3)°]. Our theoretical approaches further suggest another stable conformer for different torsions around this bridge, although this conformer was not found in the crystal phase because C–H···π intermolecular interactions contributing to assemble the supramolecular architecture of the studied compound keep only the conformer observed. Other face-to-face π···π stacking interactions and C–H···Ο contacts are also responsible for the crystal assembly.