Bis-acyl-/aroyl-hydrazones as multidentate ligands

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.

https://www.tandfonline.com/doi/pdf/10.1080/14756360290005598

Antibacterial Schiff bases of oxalyl-hydrazine/diamide incorporating pyrrolyl and salicylyl moieties and of their zinc(II) complexes.

Peroxidase-catalyzed chemiluminescence system and its application in immunoassay.

A condensation reaction of 4-acetamidobenzaldehyde with 2-aminobenzothiazole, 2-amino-4methylbenzothiazole, 2-amino-4-methoxybenzothiazole, 2-amino-4-chlorobenzothiazole, 2-amino-6nitrobenzothiazole and 6-(methylsulfonyl)benzothiazole to form tridentate Schiff bases was used. These Schiff bases have been converted into their Zn(II) chelates. These Schiff bases and Zn(II) chelates of the type [M(L)2]C12 have been characterized by physical, spectral, and analytical data. The Schiff bases act tridentately and are proposed to have octahedral geometry. These compounds have also been screened for their antibacterial properties against pathogenic bacterial species i.e., Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. INTRODUCTION Benzothiazoles are well known biologically active compounds'". Much research has been focused" to highlight the ligational and biological behavior of Schiff bases and their derivatives. The azomethine linkage (CH=N), is significant feature that makes them interesting candidates" for biological activities as well as in the coordination chemistry. The biological activity of certain compounds is related to their ability to form complexes with the metal ions which may induce through coordination a "lock geometry" of the apoprotein metal binding site so that only certain substances are able to become attached to the framework formed by this interaction. Many of the anticancer drugs are versatile ligands, some of which exhibit increased 10 ?Π anticancer activity when administered in the form of their metal complexes ' . It has been suggested" despite some controversy that certain types of cancers are virus-caused. The interaction between the metal ion and the ligand with cancer-associated viruses might represent an important route in designing new anticancer therapies. The inverse process, i.e., coordinating a metal ion from an important biomolecule, for instance a zinc finger protein, has recently been used to design novel antiviral therapies, targeted against virus-causing infections 4 . All these observations and the essential role of azomethine linkage attracted our attention to synthesize some benzothiazole derived Schiff bases (HL'-HL ) (Fig 1) and their Zn(II) chelates (Table 2) and to study their biological behavior via their coordination with the expectation that this alteration may result in achieving new targets in synthesizing and designing of compounds that could fight agressively against antibiotic resistant strains. These synthesized compounds have been characterized by physical, spectral and analytical data and also screened for their antibacterial activities against pathogenic bacterial species i.e., Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. R=4-H (L) R=4-CH3 (L) R=4-OCH3(L) R=4-C1 (L) R=6-N02 (L) R=6-S02CH3 (L) Fig 1. Structure of Schiff bases EXPERIMENTAL Material and Methods All chemicals and solvents used were of Analar grade. All metal(II) salts were used as chlorides. IR spectra were recorded on a Philips Analytical PU 9800 FTIR spectrophotometer. UV-Visible spectra were obtained in DMF on a Hitachi U-2000 double-beam spectrophotometer. C, Η and Ν analyses was carried out by Butterworth Laboratories Ltd. Conductance of the metal complexes was determined in DMF on a Hitachi YSI-32 model conductometer. Magnetic measurements were made on solid complexes using the Gouy method. Melting points were recorded on a Gallenkamp apparatus and are uncorrected.

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ANTIBACTERIAL Zn(II) COMPOUNDS OF. SCHIFF BASES DERIVED FROM SOME BENZOTHIAZOLES

Development of ultrasensitive direct chemiluminescent enzyme immunoassay for determination of aflatoxin B1 in food products

Studies on 1,1'-bis(N-furoylhydrazonoethyl)-ferrocene and its coordination compounds with transition metals

Studies on acetylferrocenylnaphthoylhydrazone (and diacyl hydrazone) and its coordination compounds with lead(ii)

Effect of the luminol signal enhancer on the chemiluminescence intensity and kinetics

Acetylferrocenyl-3-hydroxyl-2-naphthoylhydrazone and its transition metal coordination compounds were prepared. The composition and properties of the ligand and the nature of metal to ligand bonding in its coordination compounds were characterized by elemental analyses, i.r. spectra, n.m.r. spectra, u.v.-vis. spectra, thermal analyses and molar conductivities

Acetylferrocenyl-3-hydroxyl-2-naphthoylhyldrazone and its transition metal complexes

Acetylferrocenyl-3-hydroxyl-2-naphthoylhydrazone and its transition metal coordination compounds were prepared. The composition and properties of the ligand and the nature of metal to ligand bonding in its coordination compounds were characterized by elemental analyses, i.r. spectra, n.m.r. spectra, u.v.-vis. spectra, thermal analyses and molar conductivities.

Zhang Hongquan

Papers

Studies on 1,1'-bis(N-furoylhydrazonoethyl)-ferrocene and its coordination compounds with transition metals

Studies on acetylferrocenylnaphthoylhydrazone (and diacyl hydrazone) and its coordination compounds with lead(ii)

Effect of the luminol signal enhancer on the chemiluminescence intensity and kinetics

Acetylferrocenyl-3-hydroxyl-2-naphthoylhyldrazone and its transition metal complexes

Acetylferrocenyl-3-hydroxyl-2-naphthoylhydrazone and its transition metal complexes