Pragnesh K. Panchal

Bactericidal activity of different oxovanadium(IV) complexes with Schiff bases and application of chelation theory

Oxovanadium(IV) complexes have been synthesized and characterized the general composition [VOL(A)], where H2L = salicylidene-o-aminothiophenol A1 = bis(benzylidene)ethylenediamine, A2 = bis(acetophenone)ethylenediamine, A3 = 2,2′-bipyridylamine, A4 = bis(benzylidene) − 1,8-diaminonaphthalene, A5 = thiophene-o-carboxaldeneaniline and A6 = thiophene-o-carboxaldene-p-anisidine. Spectral studies indicate that the oxovanadium(IV) complexes assume a six-coordinate octahedral geometry. The antibacterial activities of the complexes against Salmonella typhi, Escherichia coli and Serratia mercescens are higher as compared to the free ligands, vanadyl sulphate, and the control (DMSO) but of moderate activity as compared to the standard drug (tetracycline).

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, characterization and toxic activity of oxovanadium(IV) mixed-ligand complexes

New oxovanadium(IV) mixed-ligand complexes of the general composition [VO(L)(A)], where KHL = potassium salt of salicylideneglycine, A1 = bis(benzylidene)ethylenediamine, A2 = bis (acetophenone)ethylenediamine, A3 = di(2-pyridyl)amine, A4 = bis(benzylidene)-1,8-diaminonaphthalene, A5 = thiophene-o-carboxaldene-aniline, A6 = thiophene-o-carboxaldene-p-anisidine, have been synthesized by the interaction of these ligands with vanadyl sulphate. The mixed-ligand complexes have been characterized on the basis of elemental analysis, magnetic measurements, electronic and infrared spectra. An octahedral structure has tentatively been assigned to all of the mixed-ligand complexes. The mixed-ligand complexes show higher toxic activity against the Salmonella typhi, Escherichia coli and Serratia mercescen as compared to the ligands, vanadyl sulphate and control (dimethyl sulphoxide). The mixed-ligand complexes were also tested against a standard drug (tetracycline).

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.

Preparation and Thermal, Spectroscopic, and Antibacterial Studies of Some Mixed‐Ligand Complexes

Abstract The present investigation reports the synthesis, characterization, and antibacterial activities of some mixed‐ligand complexes of the type [ML(SB)H2O], where M = Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II), SB1 = bis(benzylidene)ethylenediamine (benen) or SB2 = bis(acetophenone)ethylenediamine (acphen) and KHL = potassium salt of salicylideneglycine (salgly). Their structures have been elucidated on the basis of elemental analyses, thermogravimetric analyses, magnetic measurements, reflectance spectra, and IR spectra. The results are in accord with an octahedral environment around the central metal ion. The mixed‐ligand complexes of Mn(II), Co(II), Ni(II), and Cu(II) are paramagnetic while the Zn(II) and Cd(II) complexes are diamagnetic. The mixed‐ligand complexes have been tested against bacteria and the results are compared with a standard drug (tetracycline) and control (dimethyl sulfoxide).

Polymeric Coordination Compounds Derived from Transition Metal(II) with Tetradentate Schiff‐base: Synthetic, Spectroscopic, Magnetic and Thermal Approach

The polymeric coordination compounds have been synthesized using the dipotassium salt of N,N′‐di(carboxymethylene)terephthalaldehydediimine (K2SB1) or N,N′‐di(carboxyethylene)terephthalaldehydediimine (K2SB2) with manganese(II), cobalt(II), nickel(II), copper(II), zinc(II), and cadmium(II). The ligands have been characterized by 1H‐NMR, and 13C‐NMR spectra. The polychelates have been characterized by elemental analyses, magnetic measurements, thermogravimetric analyses, electronic spectra and infrared spectra. The coordination compounds are colored, and the central metal ions are octahedrally coordinated with two water molecules and the Schiff bases. The Schiff bases act as di‐negative tetradentate ligands, in which bonding occurs through two oxygen and two nitrogen atoms. The polymers are insoluble in all common organic solvents such as acetone, methanol, ethanol, N,N‐dimethylformamide and dimethylsulfoxide.

Toxic effect of transition metal complexes on Salmonella typhi, Escherichia coli and Serratia marcescens

The present article describes the synthesis, structural features and toxicological studies of the complexes of the type [M(L)(dipy-amine)(H2O)] or [M(L)(bendan)(H2O)] where M = Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II), H2L = salicylidene-o-aminothiophenol, dipy-amine =di(2-pyridyal)amine, or bendan = bis(benzylidene)1,8-diaminonaphthalene. The complexes have been characterized on the basis of elemental analyses, electronic spectra, magnetic measurement and thermogravimetric analyses. The nature of the bonding has been discussed on the basis of infrared 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 complexes of Mn(II), Co(II), Ni(II), Cu(II) are paramagnetic, while Zn(II) and Cd(II) are diamagnetic in nature. The toxic effects of the investigated complexes were tested against three Gram-negative bacteria, Salmonella typhi, Escherichia coli and Serratia marcescens by the “Disc Diffusion Method”. It is observed that the complexes show higher toxic effects as compared to the ligands, metal salts and control (DMSO), but moderate toxic effects as compared to the standard drug (tetracycline) and the results are discussed.

Synthesis, Spectral, and Biocidal Studies of Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) Mixed‐Ligand Complexes

Abstract Complexes of transition metals with salicylaldehyde (salH) or 5‐bromo‐salicylaldehyde (Br‐salH) in 1:2 molar ratio, have the compositions [M(H2O)2(sal)2] · H2O (1) or [M(H2O)2(Br‐sal)2] · H2O (2), respectively. The Schiff base derived from ethylenediamine and acetophenone in 1:1 molar ratio in alcoholic solution yields bis(acetophenone)ethylenediamine (acphen). Further reaction of (1) or (2) with acphen in alcohol yielded mixed‐ligand complexes of the type [M(sal)2acphen] or [M(Br‐sal)2 acphen], respectively. All of these complexes are soluble in ethanol and methanol. They were characterized on the basis of elemental analyses, magnetic measurements, infrared spectra, electronic spectra, and thermogravimetric analyses. All of these complexes have been screened for their antimicrobial activity against bacterial strands using the agar diffusion method.