Antibacterial Schiff Bases of Oxalyl-hydrazine/diamide Incorporating Pyrrolyl and Salicylyl Moieties and of Their Zinc(II) Complexes

Abstract

Schiff bases derived from oxaldiamide/oxalylhydrazine and pyrrol-2-carbaldehyde, or salicylaldehyde respectively, as well as their Zn(II) complexes have been prepared and tested as antibacterial agents. These Schiff bases function as tetradentate ligands, forming octahedral Zn(II) complexes. The ketonic form for the diamide derived Schiff base and the enolic form of the hydrazide derived Schiff base were the preferred tautomers for coordination of the metal ions. The title compounds and their Zn(II) derivatives were evaluated for antibacterial activity against several bacterial strains which easily develop resistance to classical antibiotics, such as Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. Some of them showed promising biological activity in inhibiting the growth of such organisms.

Antibacterial Activity of Some 3-(Arylideneamino)-2-phenylquinazoline-4(3H)-ones: Synthesis and Preliminary QSAR Studies

“…The separated solid was filtered, washed with water and recrystallized from ethanol. Cl)-, C-4"), 146.47 (C-8a), 154.00 (C-2), 159.22 (C-4), 164.40 (H-C=N) 13 …”

“…After proper assignment of the entire proton spectrum, the proton carbon correlation spectrum was further analyzed to assign the eleven 13 C-H peaks. The quaternary carbon peaks were assigned intuitively with the help of 13 C-NMR spectra.…”

“…In this paper, we would like to report the synthesis of ten 3-(arylidene-amino)-2-phenylquinazoline-4(3H)-ones and their antibacterial activity. Hydrazinederived Schiff bases have potential antibacterial activity [13]. Expecting an enhancement of biological activity we have placed two potential bio-active sites, a quinazolone moiety as well as a Schiff base in our systems.…”

Synthesis, characterization and antibacterial properties of some trivalent metal complexes with [(2-hydroxy-1-naphthaldehyde)-3-isatin]-bishydrazone

“…A heterocyclic ligand with multifunctionality has a greater chance of interaction either with nucleoside bases or with biologically essential metal ions present in the biosystem and can be promising candidates as bactericides since they always tend to interact especially with some enzymatic functional groups, in order to achieve higher coordination numbers [23,24]. Moreover, enhancement in antibacterial activity on coordination with metal ion is probably due to the presence of donor systems in the uncoordinated compound or the coordinately unsaturated species formed may inhibit enzyme production since the enzymes which require these groups for their activity, appear to be more susceptible to deactivation upon coordination [25]. Thus antibacterial property of metal complexes cannot be ascribed to chelation alone but it is an intricate blend of all the above contributions.…”

Copper (II) and zinc (ii) metal-based salicyl-, furanyl-, thienyl- and pyrrolyl-derived ONNO, NNNO, ONNS & NNNS donor asymmetrically mixed schiff-bases with antibacterial and antifungal potentials

“…The plates were incubated immediately at 378C for 20 h. Activity was determined by measuring the diameter of zones showing complete inhibition (mm). Growth inhibition was compared [19] with the standard drug (Tables II & III). In order to clarify any participating role of DMF in the biological screening, separate studies were carried out with the solutions alone of DMF and they showed no activity against any bacterial strains.…”