ABSTRACT

No abstract

6,7,8,9-Tetrachloro[1,3]oxazepine-1,5-dione derivatives 1b-10b have been synthesized by reacting Schiff bases 1a-10a with tetrachlorophthalic anhydride (TCPA) under (2 + 5 → 7) cycloaddition reaction conditons. All reactions had been monitored using TLC. FT IR and melting points have been used to characterize the Schiff bases; oxazepine compounds 1b-10b were characterized using FT IR, 1 H NMR and their melting points. Biological activity for oxazepine compounds has been evaluated against bacterial types (Staphylococcus aureus, Escherichia coli, Klebsiella spp.) and against a fungus (Geotrichum spp.). Variable activities have been observed against used strains of bacteria and fungi.

Schiff's Bases were synthesized from the reaction of p-amino benzoic acid and alkoxybenzaldehyde in absolute ethanol and reacted with (E)-3-((4-hydroxybenzylidene) amino) phenol used DCC (N,N'-Dicyclocarbodiimide) and DAMP (4-(Dimethylamino) pyridine ) to 3-(((E)-4-((4-(((E)-4 alkoxy benzylidene) amino) benzoyl) oxy) benzylidene) amino) phenyl4- (E)- 4-alkoxy benzyli dene ) amino) benzoate. The structures of the products were confirmed by their melting points, FT-IR, 1HNMR spectra.

This study examines the effects of substituents and hydrogen bonding, orientations of imine linkage on the behavior of benzylidene aniline compounds as liquid crystals (LC). Compounds 4-carboxy benzylidene-4-X-aniline (X = H, F, Cl, Br, CH 3 , OCH 3) 1a-6a were synthesized by the reaction of aniline and its substituted derivatives with 4-formylbenzoic acid. Compounds 4-X-benzylidene-4-carboxy aniline (X = H, F, Cl, Br, CH 3 , OCH 3) 1b-6b were synthesized by the reaction of benzaldehyde and its substituted derivatives with 4-aminobenzoic acid using absolute ethanol as the solvent. Synthesized compounds were characterized by FT IR and 1 H NMR spectroscopy, liquid crystal properties were investigated using differential scanning calorimetry (DSC) and polarizing optical microscopy (POM) techniques. Based on the mesomorphic properties, it was proven that the compounds 2b-4b are dimorphic exhibiting a smectic and nematic phase, compounds 5b, 6b are monomorphic exhibiting a nematic phase, while compounds 1a-6a and 1b have not shown any mesophase. For compounds 1a-6a hydrogen bonding and reversing imine linkage (in comparison with compounds 1b-6b) caused the absence of their mesomorphic properties.