Biosynthesis of gold nanoparticles using aqueous extract of Ricinus cummunis leaves to augment catalytic degradation of organic dyes and study of its antifungal and antibacterial activities

In this study,biosynthesis of gold nanoparticles(Au NPs)using aqueous extract of fresh leaves of Ricinus cummunis plant is reported without the use of any synthetic chemical in the reaction process.The prepared NPs are mostly spherical in shape with some particles having triangular or hexagonal struc-tures.The average size of the particles as calculated using TEM data is 18 nm.The biosynthesised Au NPs were studied for their application in remediation of Congo Red,Methylene Blue,Reactive Red 120 and Rhodamine B dyes present in industrial effluents.The degradation of dyes was confirmed spectropho-tometrically using UV-Vis Spectrophotometer.Reactive Red 120 and Congo red dyes were most effec-tively reduced with 88%degradation.The Au NPs were further studied for their potential as an effective antifungal agent against fungal strains namely Candida albicans and Aspergillus fumigatus and antibac-terial properties against Bacillus subtilis(Gram+ve)and Pseudomonas aeruginosa(Gram-ve)bacterial strains.The MIC values being 7.8 and 15.6(μg/mL)for Bacillus subtilis and Pseudomonas aeruginosa respectively.

Spectral, Thermal and Antibacterial Studies for Bivalent Metal Complexes of Oxalyl, Malonyl and Succinyl-bis-4-phenylthiosemicarbazide Ligands

The thermogravimetry (TG) and derivative thermogravimetry (DTG) have been used to study the thermal decomposition of some oxalyl (H4OxTSC), malonyl (H4MaTSC) and succinyl-bis-4-phenyl- thiosemicarbazide (H4SuTSC) ligands and their metal complexes using Horowitz-Metzger (HM) and Coats-Redfern methods. The kinetic thermodynamic parameters such as: E*, ΔH*, ΔS*and ΔG* are calculated from the DTG curves. The isolated complexes have the general composition [M2(L) (H2O)6], where M=Cu(II), Zn(II), L=MaTSC and M=Co(II), Cu(II) or Sn(II) and L=Su TSC and [M2(L) (H2O)n]·nH2O where M=Cu(II), Co(II) or Sn(II), L=OxTS or Ma TSC. The tested compounds show a good activity against four strains of bacteria Gram negative Escherichia coli, Pseudomonas aeruginosa species and gram-positive Bacillus cereus and Staphylococcus aureus.

Preparation, Characterization and Antimicrobial Studies of Mn(II) and Fe(II) Complexes with Schiff Base Ligand Derived from 2-aminophenol and 3-formyl-2-hydroxy-6-methoxyquinoline

Schiff base derived from 2-aminophenol and 3-formyl-2-hydroxy-6-methoxyquinoline and its Mn(II) and Fe(II) complexes were synthesized and characterized by melting point and decomposition temperature, elemental analysis, molar conductivity, infrared (IR) spectral analysis, atomic absorption spectroscopy (AAS) analysis, solubility test, and magnetic susceptibility. The Fourier-transform infrared spectroscopy (FTIR) spectral data of the Schiff base determined showed a band at 1622 cm−1 and this was assigned to the v (C=N), which is a feature of azomethine group. The same band was observed to shift to lower frequencies 1577 and 1599 cm−1 in the complexes suggesting coordination of the Schiff base with the respective metal(II) ions. Molar conductance values 14.58 and 12.65 Ω−1∙cm2∙mol−1 show that the metal complexes were non-electrolyte in nature. The magnetic susceptibility of the complexes was determined and the gram magnetic susceptibility of the complexes was found to be positive, revealing that they are paramagnetic. The elemental analysis of the complexes for C, N and H determined suggested 1:1 metal to ligand ratio. The result of the antimicrobial studies showed that, the metal(II) complexes exhibited better antibacterial and antifungal activity than the Schiff base.

Studies on condensed heterocyclic compounds II.Synthesis and antibacterial activity of 3-(4'-pyridyl)-6-aroylamino/arylamino-S-triazolo[3,4-b]-1,3,4-thiadiazoles

3-(4′-Pyridyl)-4-amino-5-mercapto-1,2,4-triazole(1)reacted with aroyl isothiocyanates 2a-1 to yield twelve novel 3-(4′-pyridyl)-6-aroylamino-S-triazolo[3,4-b]-1,3,4-thiadiazoles,4a-1. Triethylamine was necessary for the condensation of 1 with phenyl isothiocyanate(3)to give 3-(4′- pyridyl)-6-phenylamino-S-triazolo[3,4-b]-1,3,4-thiadiazole(6).The structures were confirmed by the elemental and spectral analyses.Their antibacterial activity against B.Subtilis,E.Coli,E. aerogenes and S.aureus was observed preliminary.

Novel azo dyes derived from 8-methyl-4-hydroxyl-2-quinolone:Synthesis,UV-vis studies and biological activity

In this study,N,N＇-di-（2-methylphenyl）malonamide was synthesized and reacted with polyphosphoric acid to afford 8-methyl-4-hydroxyl-2-quinolone.Eight novel azo disperse dyes were then synthesized by linking diazotized p-substituted aniline derivatives with 8-methyl-4-hydroxyl-2-quinolone.The solvatochromism of these azo dyes in various solvents was evaluated.All the compounds were then evaluated for their antibacterial activity against four bacteria,namely.Bacillus subtilis.Micrococcus luteus, Salmonella enterica,and Pseudomonas aeruginosa.The results showed that some of these compounds have high levels of antibacterial activity.

Bioassay studies of cobalt (Ⅱ) complexes of modified diamine

Coordination compounds of modified diamine,the basic unit of which are ethylenediamine,with that of Co(Ⅱ)are prepared.The modified diamines are ethylenediaceticacid(EDDA)and N,N,N,N-tetaraethylene-1,2-diamine(TEEDA).These diamines are characterized through ^(1)H-NMR,^(13)C-NMR,elemental analysis and IR techniques.Cobalt(Ⅱ)complexes of these two ligands were prepared and characterized by physical measurements including elemental analysis,IR,UVVisible,magnetic susceptibilities and conductance measurements.Antibacterial activities are also carried out in order to investigate the biological activity upon complexation.They were screened against four pathogenic bacteria like Escherichia coli,Pseudomonas aeroginosa,Klesbella pneumonia and Staphylococcus aureus.The results showed significant enhancement in activities.