Crystal structure and electronic properties of three phenylpropionic acid derivatives: A combined X-ray powder diffraction and quantum mechanical study

Crystal structures of three derivatives of phenylpropionic acid, 2, 3 and 4 with hydroxyl, methyl and methoxy substitutions at the 2, 4 positions have been determined from X-ray powder diffraction data and their electronic structures were calculated at the DFT level. The optimized molecular geometries agree closely to that obtained from the crystallographic analysis. Intermolecular O–H…O hydrogen bonds generate R 2 2 (8) rings, which are further connected through O–H…O and C–H…O hydrogen bonds into two-dimensional framework in 2 and 4, and a step like architecture in 3. The HOMO–LUMO energy gap (>4.0 eV) indicates a high kinetic stability of the three compounds.