Spectroscopic, magnetic and thermal studies of Co(II), Ni(II), Cu(II) and Zn(II) complexes of 3-acetylcoumarin–isonicotinoylhydrazone and their antimicrobial and anti-tubercular activity evaluation

Synthesis, characterization and anticancer activity of 3-formylchromone benzoylhydrazone metal complexes

“…In the spectra of the complexes, the azomethine proton (CH=N) and 2-H signals are shifted downfield indicating the participation of the former group in coordination [34,35]. In complexes, (3), (4), (5) and (8), the NH signals were absent, indicative of deprotonation of the enolized hydrazone, i.e., fcbh -functions as a mononegative tridentate ligand through pyrone carbonyl oxygen, azomethine nitrogen and deprotonated enolized hydrazone oxygen atoms [31]. In the case of complexes (1), (2), (6) and (7), the NH signal was slightly shifted downfield, indicating the neutral tridentate behavior of Hfcbh [36].…”

“…1). In complexes (3), (4), (5) and (8), the m(C=O) hydrazonic stretches were missing, while a new band appears near 1,590 cm -1 that is attributed to deprotonation of the enolized hydrazone upon complex formation [31]. In these complexes, the fcbh - The IR spectra of complexes (1) and (4) exhibit strong bands near 1,100 and 755 cm -1 due to m(P-C) and d(CCH) vibrations, respectively [8,9].…”

Synthesis, spectroscopic studies and inhibitory activity against bactria and fungi of acyclic and macrocyclic transition metal complexes containing a triamine coumarine Schiff base ligand

“…Further evidence of the bonding is given by the appearance of new bands in the spectra of the metal complexes of medium or weak intensity between 533 and 554 cm -1 can be assigned to ν(M-O)[34,35]. On the other hand, the spectra of mononuclear Co(II) and Ni(II) complexes, show another behavior where none of the carbonyl lacton groups involve into the coordination and remain unchanged[36,37].…”

Synthesis, characterization and biological activity of Cu(II), Zn(II) and Re(I) complexes derived from S-benzyldithiocarbazate and 3-acetylcoumarin

“…The spectrum of SBCM-H in DMSO-d 6 also showed a double set of signals due to the presence of SBCM-H in two isomeric forms. Isomerism was also observed by Hunoor et al (2010) with 3-acetylcoumarin-isonicotinoylhydrazone. According to Su and Aprahamian (2014), for most Schiff bases, the more stable diastereoisomer is the E since the Z diastereoisomer of an hydrazone bond is an ephemeral species.…”