Synthesis and Antimicrobial Studies of Tridentate Schiff Base Ligands with Pyrazolone Moiety and Their Metal Complexes

Abstract

In solvolysis studies using Grunwald-Winstein plots, dispersions were observed for substrates with aromatic rings at the α-carbon. Several examples for the unimolecular solvolysis of monoaryl benzylic derivatives and related diaryl- or naphthyl- substituted derivatives have now been reported, where the application of the aromatic ring parameter (I) removes this dispersion. A recent claim suggesting the presence of an appreciable nucleophilic component to the I scale, has now been shown, in a review of the solvolysis of highly-hindered alkyl halides, to be unlikely to be correct. Attention is now focused on the application of the hI term for the solvolysis of compounds containing a double bond in the vicinity of any developing carbocation. Available specific rates of solvolysis (plus some new values) at 25°C of cinnamyl chloride, cinnamyl bromide, cinnamoyl chloride, p-chlorocinnamoyl chloride, and p-nitrocinnamoyl chloride are analyzed using the simple and extended (including the hI term) Grunwald-Winstein equations.

Recent developments of metal-based compounds against fungal pathogens

“…Pyrazolyl-Schiff bases formed between 3-methyl-1-phenyl-4-acetylpyrazolin-5-ol and 1,2-diaminobenzene or 2-aminophenol were reported in 2010. 150 Complexation with V(IV), Fe(III), Cu(II), and Co(II) ions yielded eight different complexes. The tridentate ligands coordinated as ONN or ONO donors via the pyrazolyl oxygen, azomethine nitrogen and phenol or amino O/N (Fig.…”

Crystal structure of (Z)-4-[1-(4-acetylanilino)ethylidene]-3-methyl-1-phenyl-1H-pyrazol-5(4H)-one

“…Depending on the tautomers, two types of intramolecular hydrogen bonds are possible: O-HÁ Á ÁN in the enol-imine and N-HÁ Á ÁO in the keto-amine form. Schiff bases derived from acyl pyrazones and aromatic amines have been prepared as antimicrobial agents (Parmar et al, 2015) and also as ligands for the formation of metal-ion complexes (Jayarajan et al, 2010;Moorjani et al, 2010). A compound similar to the title compound, 5-methyl-2-phenyl-4-{1-[(pyridin-2-ylmethyl)-amino]-ethylidene}-2,4-dihydro-pyrazol-3-one derived from acyl pyrazolone and aliphatic amine was reported to possesses the amino-one structure (Amarasekara et al, 2009).…”

Anti-pathogenic Activity of Cu(II) Complexes Incorporating Schiff Bases: A Short Review

“…Proposed structure of complexes.The antifungal activities of ligand (HL) and complexes were screened against two different fungi, Aspergillus flavus (A. flavus) and Aspergillus niger (A. niger) strains & ketoconazole was used as standard drug[30]. The condensation product of 4-acetyl-3-methyl-1-phenylpyrazol-5-ones (mainly exists as the 3-methyl-1-phenyl-4-acetylpyrazolin-5-ol tautomer) with 1,2-diaminobenzene, and 2-aminophenol resulted in ONN-and ONO-type tridentate ligands & their transition metal complexes of VO(II), Cu(II), Fe(III), and Co(II) were synthesized by Ramasamy Jayarajan et al The complexes tested for antifungal activity against C. albicans, Rhizopus sp., and A. niger compared to the ligands and showed enhanced antifungal activity[45]. Praveen S.Mane et al have synthesized the solid complexes of Cu(II), Ni(II), Co(II), Mn(II) and Fe(III) with Schiff base ligands derived from heterocyclic compounds 3-acetyl-6-methyl-(2H)-pyran-2,4(3H)-dione (Dehydroacetic acid) and o-chloroaniline.…”