Liquid crystalline properties of copper(II) complexes derived from azo-containing salicylaldimine ligands

Structural and biological behaviors of some nonionic Schiff-base amphiphiles and their Cu(II) and Fe(III) metal complexes

“…The product was washed by petroleum ether and recrystallized from ethanol. The final product was dried under vacuum at 40 • C [18]. The produced Schiff base was denoted as SB and its chemical structure was represented in Scheme 1.…”

Synthesis, 2D NMR and X-ray diffraction studies on Cu(II) and Ni(II) complexes with ligands derived from azobenzene-cored Schiff base: Mesomorphic behaviors of Cu(II)–phenolates and crystal structure of bis[4-(4-alkoxy-2-hydroxybenzylideneamino)azobenzene]copper(II)

“…All other proton signals close to the paramagnetic Cu(II) and Ni(II) centers are not observable [3,22,23].…”

“…The strong band observed at 1610-1611 cm À1 corresponds to the stretching of azomethine, C@N. The reduction of C@N frequency as compared with free ligands suggests the coordination of N atom from the ligand to the central metal atom [22,24,5,30,31]. On the other hand, the disappearance of the OAH band of free ligands in the Ni(II) and Cu(II) metal complexes indicates that OH group is deprotonated and then it is coordinated to the metal ion [22,24,29,5,30]. Furthermore, the coordination of oxygen to metal ion is further confirmed by the stretching vibration of phenolic CAO shifted to higher frequency at 1311-1313 cm À1 for Cu(II) and Ni(II) complexes [27,32].…”

Synthesis and Liquid-Crystalline Properties of N,N′-di-(5-(4-Alkoxyphenyl)azo)-Salicylidene-1,2-Phenylene Diiminato Nickel(II) Complexes

“…As a part of our systematic investigation [16][17][18][19][20][21] on structural and thermal studies of Cu þ2 , Ni þ2 , and VO þ2 metal complexes with azo-linked salicylaldimine Schiff-base derivatives, we report here the results of our investigation on the synthesis and liquid-crystalline character of tetradentate Schiff base N,N 0 -di-(5-(4-alkoxyphenyl)azo)-salicylidene-1,2 phenylene diimine and the corresponding nickel(II) complexes (see Scheme 1).…”