Synthesis and evaluation of Quarternary quinolinium salts as potential fungicides.(Completed in September 2017)

Summary of project:

Quinoline and its quaternary quinolinium salts were synthesized by refluxing the quinoline with the different alkyl halides. All the physical characteristics of the synthesized compounds were recorded i.e. color, melting point and appearance. All the compounds were obtained in good yields. Most of the synthesized compounds were liquid while other compounds were obtained in the pure crystalline form. Synthesized compounds that were obtained in solid form have low melting points in the range of 48-92^oC. Various physico-chemical techniques viz. FT-IR, ¹H NMR and ¹³C NMR were used for the analysis of the synthesized compounds. Compounds were evaluated in vitro for antifungal potential against Fusarium verticilloides, Drechslera oryzae, Helminthosporium oryzae, Bipolaris sorokiniana and Puccinia triticina by spore germination inhibition method at different concentrations i.e.1000, 500, 250, 100 and 50μg/ml and per cent spore inhibition was calculated for the synthesized compounds. Then evaluation of fungi-toxicity of all compounds was done by calculating the ED₅₀ (effective dose at which 50 per cent inhibition takes place). All the tested compounds were found to be active against all the test fungi. Analysis of data was done statistically using (2-way ANOVA) C-pcs software when the compounds were tested against Fusarium verticilloides and Drechslera oryzae. The correlation between all concentrations and synthesized quinolinium salts and the values of per cent spore inhibition were significant at different concentrations. Some of the compounds at higher concentration were also found statistically at par. The decreasing order varies as C-8 quinolinium bromide > C-6 quinolinium bromide > C-7 quinolinium bromide > C-10 quinolinium bromide in the case of two fungi i.e. Fusarium verticilloides and Drechslera oryzae. The quinolinium salt that contain unsaturated hydrocarbon chain was found to be more effective against Fusarium verticilloides but when tested against the Drechslera oryzae, compound C-6 quinoliniumbromide, showed the best activity among the synthesized compound which was very close to the standard fungicide used. In case of Drechslera oryzae quinolinium salts those contain very small hydrocarbon chain from C-1 to C-5 showed zero inhibition at 50 μg/ml but they are somewhat effective against Fusarium verticilloides at same concentration. In case of other three fungi i.e. Helminthosporium,oryzae, Bipolaris sorokiniana and Puccinia triticina, when compounds were tested against Helminthosporium oryzae no regular trend was found in inhibition with increase in hydrocarbon chain but when compounds tested against Bipolaris sorokiniana and Puccinia triticina quaternary salts of substituted quinoline compound (R¹ = 4-Me, R² = butyl) was found most effective than all of the synthesized compounds.

Nanofabrication of ferrite and clay composites and their application for remediation of heavy metals (Completed in March 2017)

Summary of Project:

Nanocomposites of magnesium and calcium ferrite nanoparticles (NPs) with bentonite clay were synthesized. The nanocomposites were characterized by various physico-chemical techniques viz. Transmission electron microscope (TEM), X-ray diffraction (XRD), Vibrating sample magnetometer (VSM), FT-IR spectroscopy, Scanning electron microscopy-Energy dispersive spectroscopy (SEM-EDS) and Brunauer Emmett Teller (BET) surface analysis. FT-IR analysis of composite confirmed the presence of bentonite clay from a distinct peak due to Si-O-Al frame work vibration at 1048 cm^-1. BET surface area analysis confirmed decrease in the area under the hysteresis loop with increase in clay content in the composite. The hysteresis loops of type-IV confirmed mesoporous nature of the synthesized nanocomposite. VSM analysis showed that composite had lower saturation magnetization as compared to the pristine ferrite NPs. Addition of small amount of bentonite clay to the reaction mixture during synthesis of nanocomposite resulted in increase in the porosity of the nanocomposite as compared to the pristine ferrite NPs. Sol-gel method was observed to be most effective method for synthesis of nanocomposite with high adsorptive properties Magnesium ferrite NPs displayed higher adsorption potential as compared to calcium ferrite clay composite. Magnesium ferrite bentonite clay composite with w: w ratio of 1:1, 1: 0.5, 1: 0.25 and 1:0.05 were synthesized. The nanocomposite with w/w ratio of 1:0.05 was observed have highest surface area among synthesized nanocomposites. So detailed adsorption analysis was performed on with this nanocomposite. Adsorption data was modeled using Langmuir, Freundlich, Dubinin Radushkevitch and Temkin isotherm models. The adsorption of Cr (VI) was favored at optimum pH of 2. The observed trend for percentage removal of Cr (VI) was activated charcoal> nanocomposite> Ferrite NPs> bentonite. Activated charcoal displayed better removal than nanocomposite which was explained on the basis of reluctant nature of activated charcoal whereas Cr (VI) ions act as oxidant at optimum pH of 2 and redox reaction was responsible for higher percentage removal. The trend for the percentage removal of Pb (II) and Ni (II) ions in the descending order was nanocxomposite> MgFe₂O₄ NPs> Bentonite > activated charcoal. The nanocomposite was reusable after desorption with the stripping solution of 0.1N NaOH in case of Cr (VI) and 0.1N HCl in case of Ni (II) and Pb (II) ions. Nanocomposite retained its adsorption capacity even after repeated cycles of regeneration. The separation of activated carbon after adsorption is a problematic issue. Whereas nanocomposite is easily magnetically separable. These studies have proven the potential future applications of magnetic nanocomposites based on magnesium ferrite and bentonite clay in the field of adsorptive removal of contaminants.