Studies on Some Schiff Base Complexes of Co^II, Ni^IIand Cu^IIDerived from Salicylaldehyde and O-Nitrobenzaldehyde

Synthesis, spectral characterization, solution equilibria, in vitro antibacterial and cytotoxic activities of Cu(II), Ni(II), Mn(II), Co(II) and Zn(II) complexes with Schiff base derived from 5-bromosalicylaldehyde and 2-aminomethylthiophene

“…The IR spectrum of ligand (ATS) reveals a broad band in the 3361-3543 cm −1 region assigned to the (OH) group. The disappearance of this band in the spectra of the complexes indicates the deprotonation of the hydroxyl group and coordination through deprotonated phenolic OH group [31,32]. In the free ATS ligand, the high intensity band due to (C-O) (aromatic carbon and phenolic oxygen) at 1319 cm −1 [33] appeared as a medium intensity band in the 1382-1386 cm −1 region, indicating coordination of the phenolic oxygen atom to the metal ion [34] and formation of M-O bond via deprotonation.…”

Preparation, Chemical Characterization and Electronic Spectra of 6-(2-Pyridylazo)-3-Acetamidophenol and Its Metal Complexes

“…The IR spectrum of the ligand reveals a band at 3566 cm" due to v (OH). This band is absent in the Cu (II), Zn (II), Cd (11) and Fe (111) complexes, indicating coordination through a deprotonated phenolic OH group". While in Co (11) and Ni (11) complexes, this band was broadenedd, decreased in intensity, and shifted to a lower frequency indicating its participation in complex formation via the protonated phenolic OH group.…”

“…This band is absent in the Cu (II), Zn (II), Cd (11) and Fe (111) complexes, indicating coordination through a deprotonated phenolic OH group". While in Co (11) and Ni (11) complexes, this band was broadenedd, decreased in intensity, and shifted to a lower frequency indicating its participation in complex formation via the protonated phenolic OH group. The spectra of the solid complexes exhibits a broad band at 3500-3400 cm", which attributed to uoH of the associated water molecules, while the band observed at approximately 850-780 cm-' is assigned to coordinated water molecules"*'.…”

Mixed bivalent transition metal complexes of 1,10-phenanthroline and 2-aminomethylthiophenyl-4-bromosalicylaldehyde Schiff base: Spectroscopic, molecular modeling and biological activities

“…The IR spectrum of ligand (ATS) reveals a broad band in the 3361-3543 cm -1 region assigned to the to ν(OH) group. The disappearance of this band in the spectra of the complexes indicates the deprotonation of the hydroxyl group and coordination through deprotonated phenolic OH group [50,51]. The band observed for ATS ligand at 1319 cm -1 [52] due to ν(C-O) stretching frequency (aromatic carbon and phenolic oxygen), shifted to lower frequency by 19-27 cm −1 in the mixed-ligand complexes suggesting involvement of the oxygen atom to the metal ion and formation of M-O bond via deprotonation.…”