| Abstract |
Schiff base condensation of 2-nitrobenzaldehyde with (para-substituted phenyl)hydrazine in the presence of CH3COONa in EtOH at 80 degrees C produces (E)-1-(para-substituted phenyl)-2-(2-nitrobenzylidene)hydrazines [-OCH3 (1), -CH3 (2), -H (3), -Br (4), -CI (5), -F (6)]. CuCl catalyzed olefination of 1 - 6 with CCl4 in the presence of tetramethylethylenediamine (TMEDA) in DMSO leads to (E)-1-(2,2-dichloro-1-(2-nitrophenyl)vinyl)2-(para-substituted phenyl)-diazenes [-OCH3 (7), -CH3 (8), -H (9), -Br (10), -Cl (11), -F (12)], respectively. 1-12 were characterized by H-1 and C-13 NMR spectroscopies, ESI-MS, elemental and X-ray diffraction (for 8, 9 and 12) analysis. The single crystal X-ray analysis of 8, 9 and 12 evidence the intramolecular N center dot center dot center dot Cl pnicogen bonds which is significantly strengthened in view of the planarity of the four atoms involved in the 1,4-membered synthon. The intermolecular halogen and hydrogen bonds also contribute to stabilize the crystal structures of 8, 9 and 12. In DMSO solution 1-12 exist in the E-isomeric form, which stabilized by inter- and intramolecular noncovalent interactions. Solvatochromic behavior on UV-vis absorption spectra of azo dyes 7-12 were studied in CH2Cl2, DMF and MeOH, which lambda(max) is dependent on the attached substituents at para-position of aromatic moiety. |
