S. C. Chaudhry

Synthesis, characterization, and antimicrobial activity of oxovanadium(IV)hydroxamate complexes

Vanadium(IV) complexes, [VO(acac)(HL1,2)] and [VO(HL1,2)2] (I–IV) (where acac = ( ); HL1,2 = R′C(O)NHO−, R′ =–CH2OC6H5 and–CH=CHC6H5), have been synthesized by reaction of VO(acac)2 with the potassium salt of phenoxyacetohydroxamic and cinnamohydroxamic acids and characterized by elemental analyses, molar conductivity, magnetic measurements, molecular weight determinations, IR, electronic, mass spectral, and electrochemical studies. From the spectroscopic studies, O,O coordination of hydroxamate ligands and a square-pyramidal geometry for the complexes has been proposed. The antibacterial activities of VO(acac)2, the precursor, the free ligands, and the synthesized oxovanadium(IV)hydroxamate complexes against six bacteria have been assayed by the minimum inhibitory concentration method. The complexes exhibit antimicrobial activities comparable to the standard drug streptomycin.

Synthesis, characterization, and antibacterial activity of triorganotin(IV) complexes of 2-methylphenol

The triorganotin(IV) complex Ph3Sn(OPhMe-2) (1) has been synthesized by the reaction of Ph3SnCl with NaOPhMe-2, while complexes of composition n-Bu3Sn(OPhMe-2) (2) and Me3Sn(OPhMe-2) (3) (where −OPhMe-2 = −OC6H4CH3-2) have been obtained from the reaction of n-Bu3SnCl and Me3SnCl with 2-methylphenol in the presence of triethylamine in carbon tetrachloride. The complexes have been characterized by elemental analyses, molar conductance measurements, molecular weight determination, and IR, 1H NMR, 13C NMR, and mass spectral studies. Thermal behavior of the complexes has been studied by TG and DTA techniques. The organotin(IV) complexes have also been screened for antibacterial activity and exhibit appreciable activity. The reactions of the complexes with 3- and 4-cyanopyridines yielded 1 : 1 adducts authenticated by physicochemical and IR and 1H NMR spectral data.

Synthesis, characterization and acceptor behavior of n-butyltin(IV)-2,4-dimethylphenoxides

The n-butyltin(IV) complexes, n-BuSnCl3−x(OC6H3(CH3)2-2,4) x (where x = 1–3), have been synthesized in quantitative yields by employing the reaction of n-BuSnCl3 with 2,4-dimethylphenol and sodium acetate in methanol and benzene solvents at room temperature. The complexes have been characterized by elemental analysis, molar conductivity, and FT-IR, 1H- and 13C-NMR, and mass spectral studies. Thermal behavior has been studied by TG–DTA techniques. Lewis acid character of n-BuSn(OC6H3(CH3)2-2,4)3 has been investigated by reacting it with bases such as 2,2′-bipyridine and 1,10-phenanthroline (B), Ph3PO and Ph3AsO (LO) and phosphorus and arsenic donors Ph3P, Ph3As, and As(SPh)3 (L). The formation of 1 : 1 and 1 : 2 (metal : base) coordination compounds [n-BuSn(OC6H3(CH3)2-2,4)3·B] and n-[BuSn(OC6H3(CH3)2-2,4)3·2LO/2L] has been authenticated by physicochemical and IR spectral studies. In order to infer the biological relevance of newly synthesized complexes, the antibacterial activity has been assayed against six bacterial strains Klebsiella pneumoniae, Staphylococcus epidermidis, Staphylococcus aureus, Salmonella typhi, Salmonella paratyphi, and Escherichia coli. In this study, n-BuSnCl2(OC6H3(CH3)2-2,4) and n-BuSnCl(OC6H3(CH3)2-2,4)2 showed better activity than precursor and ligand, while n-BuSn(OC6H3(CH3)2-2,4)3 did not exhibit improved activity.

Synthesis, characterization, electrochemical study, and antimicrobial activity of bis(benzoylacetonato) vanadium(IV) complexes of biphenylphenols

New non-oxovanadium(IV) complexes of biphenylphenols, [VCl2− n (bzac)2(OAr1,2) n ], have been synthesized in quantitative yields from the reaction of bis(benzoylacetonato)dichlorovanadium(IV) with the trimethylsilyl derivative of 2- and 4-phenylphenols in carbon tetrachloride. The complexes have been characterized by physicochemical, magnetic moment measurements, IR, mass spectra, and electrochemical studies. The thermal behavior of the complexes has been studied by TGA–DTA. The complexes have been screened for their antimicrobial activity against some pathogenic bacteria, Escherichia coli and Staphylococcus aureus and fungi, Candida albicans, Aspergillus niger, and Fusarium oxysporum, by two-fold serial dilution.

Synthesis, characterization, and antibacterial activity of vanadium(IV) complexes of hydroxamic acids

Vanadium(IV) complexes of composition [VCl2− n (acac)2(HL1,2) n ] (1–4) (where acac = ( )HL1 = C6H5OCH2C(O)NHO−; phenoxyacetohydroxamate ion; HL2 = C6H5CH = CHC(O)NHO−; cinnamylhydroxamate ion, n = 1 and 2 have been synthesized by reaction of [VCl2(acac)2] with the potassium salt of phenoxyacetohydroxamic and cinnamylhydroxamic acids in predetermined molar ratios in THF + MeOH. The characterization of the complexes has been accomplished by elemental analyses, molar conductivity, magnetic measurements, IR, electronic, and mass spectral studies. Based upon spectral and molecular modeling dynamics, a distorted octahedral geometry around vanadium has been proposed. The thermal behavior of the complexes has been studied by TG and DTA techniques. The antibacterial activities of the newly synthesized complexes, vanadium precursor, and ligands have been assayed by the minimum inhibitory concentration method. The complexes have improved antibacterial activity over the free ligands.

Synthesis, structural characterisation and antibacterial activity of bis(1-phenyl-1,3-butanedionato)non-oxovanadium(IV) hydroxamates

Complexes with a composition of VCl2-n(bzac)2(HL1,2)n (I – IV) (where bzac = 1-phenyl-1,3-butanedionate anion (C6H5COCHCOCH3−); HL1=C6H5OCH2C(O)NHO−, HL2 = C6H5CH=CHC(O)NHO−, n = 1 and 2) have been synthesised from the reactions of (VCl2(bzac)2) with equi- and bi-molar amounts of potassium phenoxyacetohydroxamate and cinnamohydroxamate (KHL1,2) in THF + MeOH solvent medium. The complexes have been characterised by elemental analyses, molar conductivity, magnetic measurements, IR, electronic and mass spectral studies. The physicochemical and spectral studies suggest a distorted octahedral geometry around vanadium in the complexes. The antibacterial activities of the newly synthesised complexes, vanadium precursor and ligands have been screened in vitro against six bacterial species. The complexes have shown higher antibacterial effect than the free ligands.

Monooxovanadium(V) 2-phenylphenoxides: synthesis, characterization, and antimicrobial potential

Monooxovanadium(V) complexes of the composition VOCl3− n (L) n (where L = 2-phenylphenoxide ion; n = 1–3) (1–3) have been synthesized in quantitative yields by the reaction of VOCl3 with 2-phenylphenol in toluene. The characterization of the complexes has been accomplished by elemental analysis, molar conductance measurements, IR, 1H-NMR, electronic, mass spectral, and thermal studies. The ligands as well as the complexes have been screened for their in vitro antimicrobial activity against the pathogenic bacteria Escherichia coli and Staphylococcus aureus and fungi Candida albicans, Aspergillus niger, and Fusarium oxysporum by a twofold serial dilution. An increase in the biocidal activity was observed for the vanadium complexes. The minimum inhibitory concentration (MIC) values were 6.25–25 µg mL−1 for complexes, relative to that of the free ligand of 25–50 µg mL−1.

Thermonanalytical investigations of monochlorobis (2,4-pentanedionato) vanadium(IV) aryloxides

The thermal decomposition of the complexes [Vcl (acac)2(OAr)] (where acac=2,4-pentanedionato anion; OAr=–OC6H4O-M-4, OC6H4OBut-4) has been studied using non-isothermal techniques (DTA and TG). The TGA indicate that the substitution of chlorine in VCl2(acac)2 with aryloxide ligands results in an increase in the initial temperature of decomposition (IDT) of the new complexes. The role of the substituent at the aryloxide ring on the thermal stability of the complexes is depicted and hence described. The ultimate decomposition product in all the complexes has been identified as V2O5. The kinetic and thermodynamic parameters namely, the energy of activation E, the frequency factor A, entropy of activation S and specific reaction rate constant kr etc. have been rationalized in relation to the bonding aspect of the aryloxide ligands.

4-METHOXYPHENOXO COMPLEXES OF MONOOXOVANADIUM(V) AND THEIR REACTIONS WITH CYANOANILINES AND CYANOPYRIDINES

Abstract The new 4-methoxyphenoxomonooxovanadium(V) complexes with the general formulae [VOCl3−x(OC6H4OMe-4)x] (where x = 1 → 3) have been conveniently synthesized in good yields using VOCl3 and the trimethylsilyl derivative of 4-methoxyphenol, Me3SiOC6H4OMe-4 as reactants in CCl4. The complexes were characterized by chemical analyses, conductively measurements, IR,1H NMR, electronic spectra and thermal studies. Coordination compounds of the parent complexes with cyanoanilines and cyanopyridines have been prepared and studied. Tentative stereochemistries are assigned in each case.

Synthesis and Reactions of Tetrakis(4-Methoxyphenoxo)titanium(IV)

Abstract The compound of the composition Ti(0C6H40Me-4)4 (I) has been isolated by reacting titanium tetra-chloride with 4-methoxy-phenol in 1:4 molar ratio in benzene and characterised on the basis of elemental analyses, conductance, molecular weights, IR and NMR spectral studies. Reactions of (I) with α -hydroxy-aldehydes and ketones and some nitrogenous bases such as 1,10-phenanthroline and 2,2-bipyridylhave also been investigated.