Synthesis, X‐Ray Structural Analysis, Supramolecular Properties, and Computational Study of New Aromatic Azo Compounds

This article discusses the synthesis of aromatic azo compounds based on tert ‐butylbenzaldehyde. The synthesized compounds ( E )‐1‐(1‐(4‐( tert ‐butyl)phenyl)‐2,2‐dichlorovinyl)‐2‐(4‐chlorophenyl)diazene (I), ( E )‐1‐(2,2‐dibromo‐1‐(4‐( tert ‐butyl)phenyl)vinyl)‐2‐phenyldiazene (II) , and ( E )‐1‐(2,2‐dibromo‐1‐(4‐( tert ‐butyl)phenyl)vinyl)‐2‐(4‐methoxyphenyl)diazene (III) were characterized by 1 H and 13 C NMR spectroscopy. Moreover, the crystal structure of compounds was explored by single‐crystal X‐ray diffraction (SC‐XRD) analysis. The diffraction analysis showed that the substitution on the aromatic ring affects the dihedral angle between rings, and a distinction between supramolecular assemblies is noticed. The inclination between aromatic rings is 79.96 (4)°, 78.76 (8)°, and 77.42 (7)° for compounds I–III , respectively. The supramolecular assembly of compounds I and II is stabilized by C–H⋅⋅⋅Cl and C–H⋅⋅⋅O bonding, respectively, whereas compound III has no conventional H‐bonding. The H⋯π interactions are observed at distances of 2.85 Å in compound I and 2.88 Å in compounds II and III , whereas the corresponding halogen⋯π distances are 3.6260 (7), 3.5660 (13), and 3.7934 (10) Å for compounds I , II , and III , respectively. The H⋯H contact predominates in the supramolecular assembly (34.4%, 44.2%, and 42.6% for I–III ), along with notable H⋯halogen and H⋯carbon interactions in all compounds. Furthermore, the crystal structure data have been employed to theoretically determine UV–visible, FT‐IR, NMR, highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) energies, frontier molecular orbitals, and molecular electrostatic potential through the DFT/B3LYP/6‐311+g(2d,p) level of theory. The HOMO–LUMO energy gaps are 5.75, 5.26, and 5.23 eV for compounds I–III , respectively, indicating that the bromo‐substituted derivative is the most reactive among them. The DFT results were found to be consistent with the experimental findings.