Halogenated Diazabutadiene Dyes: Synthesis, Structures, Supramolecular Features, and Theoretical Studies.

Novel halogenated aromatic dichlorodiazadienes were prepared via copper-mediated oxidative coupling between the corresponding hydrazones and CCl4. These rare azo-dyes were characterized using 1H and 13C NMR techniques and X-ray diffraction analysis for five halogenated dichlorodiazadienes. Multiple non-covalent halogen···halogen interactions were detected in the solid state and studied by DFT calculations and topological analysis of the electron density distribution within the framework of Bader's theory (QTAIM method). Theoretical studies demonstrated that non-covalent halogen···halogen interactions play crucial role in self-assembly of highly polarizable dichlorodiazadienes. Thus, halogen bonding can dictate a packing preference in the solid state for this class of dichloro-substituted heterodienes, which could be a convenient tool for a fine tuning of the properties of this novel class of dyes.

Crystal structure and Hirshfeld surface analysis of (E)-1-(4-chloro-phen-yl)-2-[2,2-di-chloro-1-(4-fluoro-phen-yl)ethen-yl]diazene.

In the title compound, C14H8Cl3FN2, the planes of the 4-fluoro-phenyl ring and the 4-chloro-phenyl ring make a dihedral angle of 56.13 (13)°. In the crystal, mol-ecules are stacked in a column along the a axis via a weak C-H⋯Cl hydrogen bond and face-to-face π-π stacking inter-actions [centroid-centroid distances = 3.8615 (18) and 3.8619 (18) Å]. The crystal packing is further stabilized by short Cl⋯Cl contacts. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from Cl⋯H/H⋯Cl (31.2%), H⋯H (14.8%), C⋯H/H⋯C (14.0%), F⋯H/H⋯F (12.8%), C⋯C (9.0%) and Cl⋯Cl (6.7%) inter-actions.

Crystal structure and Hirshfeld surface analysis of (E)-1-[2,2-di-chloro-1-(4-nitro-phen-yl)ethen-yl]-2-(4-fluoro-phen-yl)diazene.

In the title compound, C14H8Cl2FN3O2, the 4-fluoro-phenyl ring and the nitro-substituted benzene ring form a dihedral angle of 63.29 (8)°. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds into chains running parallel to the c axis. The crystal packing is further stabilized by C-Cl⋯π, C-F⋯π and N-O⋯π inter-actions. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions to the crystal packing are from H⋯O/O⋯H (15.5%), H⋯H (15.3%), Cl⋯H/H⋯Cl (13.8%), C⋯H/H⋯C (9.5%) and F⋯H/H⋯F (8.2%) inter-actions.