M. N. Patel

Synthesis, Structural Characterization, and Antibacterial Studies of Some Mixed‐Ligand First Row d‐Transition Metal Complexes

Abstract Some mixed‐ligand complexes of the transition metal ions Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) with the potassium salt of salicylideneglycine and 2,2′‐bipyridylamine or di(benzylidene)‐1,8‐diaminonaphthalene have been prepared. The coordination behavior of the mixed‐ligand complexes was characterized on the basis of elemental analyses, IR, and electronic spectra. The magnetic measurements have been obtained by a vibrating sample magnetometer. It is observed that the mixed‐ligand complexes of Mn(II), Co(II), Ni(II), Cu(II) are paramagnetic, while the Zn(II) and Cd(II) complexes are diamagnetic. All of these mixed‐ligand complexes are colored crystalline solids. Octahedral geometries have been assigned to all of the prepared mixed‐ligand complexes. The antibacterial activities of the ligands, the metal chlorides, the mixed‐ligand complexes, the standard drug (tetracycline), and control (dimethyl sulfoxide) were tested on the pathogenic bacteria S. typhi, E. coli, and Serratia marcescens using the “disc diffusion method,” and the results are discussed.

In-vitro biological evaluation of some ONS and NS donor Schiff's bases and their metal complexes.

Complexes of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with the Schiff bases salicylidene-o-aminothiophenol (H2L) and thiophene-o-carboxaldeneaniline (SB) have been synthesized and characterized by elemental analyses, magnetic measurements, thermogravimetric analyses as well as infrared spectra and reflectance spectra. The nature of the bonding has been discussed on the basis of IR spectral data. Magnetic susceptibility measurements and electronic spectral data suggest a six-coordinated octahedral structure for these complexes. The complexes of Mn(II), Co(II), Ni(II), Cu(II) are paramagnetic, while Zn(II) and Cd(II) are diamagnetic in nature. The complexes were tested for their antimicrobial activities against Salmonella typhi, Escherichia coli and Serratia marcescens using the “Disc Diffusion Method”. The results are compared with the standard drug (tetracycline) and show moderate activity.

PREPARATION, MAGNETIC, SPECTRAL, AND BIOCIDAL STUDIES OF SOME TRANSITION METAL COMPLEXES WITH 3,5-DIBROMOSALICYLIDENEANILINE AND NEUTRAL BIDENTATE LIGANDS

ABSTRACT The mixed-ligand complexes of transition metal ions like Mn(II), Co(II), Ni(II), Cu(II) and Cd(II) with 3,5-dibromosalicylideneaniline (HSB) and 2,2′-bipyridylamine (Bipy-amine) or bis(benzylidene)ethylenediamine (Benen) as the secondary ligand were prepared and characterized using elemental analyses, magnetic measurements, electronic and infrared spectra. They were also tested for their antimicrobial activities against bacteria, yeast and fungi.

Metal Complexes: Preparation, Magnetic, Spectral, and Biocidal Studies of Some Mixed‐Ligand Complexes with Schiff Bases Containing NO and NN Donor Atoms

Abstract Metal complexes of the types [M(SB1)2acphen] and [M(SB2)2acphen] where M = Mn(II), Co(II), Ni(II), Cu(II), and Cd(II); HSB1 = 5‐chlorosalicylidene‐p‐anisidine and HSB2 = 5‐bromosalicylidene‐p‐anisidine have been prepared and characterized. Magnetic susceptibility measurements, elemental analyses, electro‐nic, and infrared spectral data suggest six‐coordinated octahedral structures for these complexes. The mixed‐ligand complexes show higher activity against Sacch aromyces cereuisae, Salmonella typhi, Fasarium oxysporum, and Lasiodiplodia theobromae as compared to the ligand, metal salts, and control.

Preparation, Characterization, and Antimicrobial Activities of Some Mixed‐Ligand Complexes of Mn(II), Co(II), Ni(II), Cu(II), and Cd(II) with Monobasic Bidentate (ON) Schiff Base and Neutral Bidentate (NN) Ligands

Abstract Complexes of Mn(II), Co(II), Ni(II), Cu(II), and Cd(II) with 3,5‐dibromosalicylidene‐p‐anisidene (HSB) and 2,2′‐bipyridylamine (bipyamine) or bis(benzylidene)ethylenediamine (benen) or bis(acetophenone) ethylenediamine (acphen) have been prepared. They were characterized by elemental analyses, magnetic measurements, electronic and infrared spectra. All the ligands, metal salts, and their complexes were screened for their antimicrobial activities against bacteria, yeast, and fungi and the results are discussed.

DNA-interaction and in vitro antimicrobial studies of some mixed-ligand complexes of cobalt(II) with fluoroquinolone antibacterial agent ciprofloxacin and some neutral bidentate ligands.

Six new mixed-ligand complexes of Co(II) with ciprofloxacin (Cip) and neutral bidentate ligands have been synthesized and characterized. Binding and cleavage of DNA with the complex were investigated using spectroscopic method, viscosity measurements and gel electrophoresis techniques. Antibacterial activity has been assayed against two Gram((-ve)) and three Gram((+ve)) microorganisms using the doubling dilution technique.

Five-coordinated oxovanadium(IV) complexes derived from amino acids and ciprofloxacin: synthesis, spectral, antimicrobial, and DNA interaction approach.

Five-coordinated oxovanadium(IV) complexes with ciprofloxacin and various uninegative bidentate amino acids have been prepared. The structure of complexes has been investigated using spectral, physicochemical, mass spectroscopy, and elemental analyses. The antimicrobial activities (MIC) of the complexes, ligands, metal salt, and some standard drugs have been evaluated using the doubling dilution technique against Staphylococcus aureus, Bacillus subtilis, Serratia marcescens (gram-positive), and Pseudomonas aeruginosa, and Escherichia coli (gram-negative) bacteria. The result shows the significant increase in the antibacterial activity of the ligand, metal, and ciprofloxacin on complexation. The interaction of the complexes with pBR322 DNA has been investigated using spectroscopic, gel electrophoresis, and viscometric techniques. This shows that the complexes can bind to pBR322 DNA by the intercalative mode. The superoxide dismutase-like activity of the complexes has been determined.

SYNTHESIS, CHARACTERIZATION, AND ANTIMICROBIAL ACTIVITIES OF SOME TRANSITION METAL COMPLEXES WITH A TRIDENTATE DIBASIC SCHIFF BASE AND BIDENTATE 2,2′-BIPYRIDYLAMINE

The mixed-ligand complexes of Cu(II), Ni(II), Zn(II), Co(II), Fe(II), Mn(II), and Cd(II) with 2,2′-bipyridylamine (Bipy-amine) and a Schiff base (H2SB) were prepared and characterized on the basis of elemental analyses, magnetic measurements, infrared spectra, electronic spectra and thermogravimetric analyses. An octahedral geometry has been assigned to all of the prepared complexes. The antimicrobial activities of the complexes were tested against bacteria, yeast and fungi and the results are discussed.

Study on increase in toxicity of Schiff bases on microorganism on chelation with metal

New heterochelates of the type [M(L)(SB)(H2O)] (where M = Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II), KHL = potassium salt of salicylideneglycine and SB = thiophene- O -carboxaldeneaniline) have been synthesized. The heterochelates have been characterized on the basis of elemental analyses, electronic spectra, and magnetic measurement analyses. The structural and geometrical conformation has been discussed on the basis of IR spectral data. A thermal study of the complexes has been carried out to ascertain their thermal stability. Magnetic susceptibility measurements and electronic spectral data suggest a six-coordinated octahedral structure for these complexes. The increase in toxicity of the investigated heterochelate metal compounds was tested against three gram-negative bacteria, S. typhi, E. coli, and Serratia marcescens by the disc diffusion method. It is observed that the heterochelates show higher toxicity when compared to the Schiff bases, metal salts, and control (DMSO) due to chelation. The toxicity is also compared to the standard drug tetracycline.

Synthesis and Spectral Investigation of La(III), Ce(III), Pr(III), Nd(III) and Sm(III) Coordination Chain Polymeric Assemblies

The coordination chain polymers of La(III), Ce(III), Pr(III), Sm(III) and Nd(III) with N,N′‐di(o‐carboxyphenyl)terephthalaldehydediimine have been prepared. The characterization of these newly synthesized coordination chain polymers were done by elemental analysis, magnetic measurements, infrared spectra, reflectance spectral studies and thermogravimetric analysis. The Schiff base acts as a dinegative tetradentate ligand and bonding through the oxygen and nitrogen atoms. The insolubility of the coordination chain polymers in common organic solvents suggest their polymeric nature.