Structural Organization of Dibromodiazadienes in the Crystal and Identification of Br···O Halogen Bonding Involving the Nitro Group.

Nitro functionalized dibromodiazadiene dyes were prepared and fully characterized including X-ray single crystal analysis. Electron deficient dibromodiazadienes were found to be able to act as donors of halogen bonding (XB), while the nitro group acted as an acceptor of the XB. Depending on the substituents, the Br···O XB competed with other weak interactions, and for some of the dyes, they even outcompeted the XB involving the nitro group. However, the nitro functionalized dibromoalkenes 6a and 10a, which had only the nitro moiety as the most plausible acceptor of the XB, reliably formed 1D chains via Br⋯O XB. Experimental work was supported by the DFT calculations and topological analysis of the electron density distribution within the framework of Bader's theory (QTAIM method).

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.

Hydrogen and halogen bonding in the haloetherification products in chalcone.

Cooperative action of hydrogen and halogen bonding in the reaction of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-1-phenylprop-2-en-1-one with HCl or HBr in alcohol medium under microwave irradiation (20 W, 80 °C, 10 min) allows the isolation of the haloetherification products (2S,3S)-3-(3-tert-butyl-5-chloro-4-hydroxyphenyl)-2-chloro-3-ethoxy-1-phenylpropan-1-one, C21H24Cl2O3, (2S,3S)-2-bromo-3-(3-tert-butyl-5-bromo-4-hydroxyphenyl)-3-methoxy-1-phenylpropan-1-one, C20H22Br2O3, and (2S,3S)-2-bromo-3-(3-tert-butyl-5-bromo-4-hydroxyphenyl)-3-ethoxy-1-phenylpropan-1-one, C21H24Br2O3, in good yields. Both types of noncovalent interactions, e.g. hydrogen and halogen bonds, are formed to stabilize the obtained products in the solid state.