Department Of Chemistry

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Author: search.filters.author.Kumar R.Has files: No

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    Metal- And Solvent-Free Multicomponent Decarboxylative A3-Coupling for the Synthesis of Propargylamines: Experimental, Computational, and Biological Investigations
    (American Chemical Society, 2020) Kaur P.; Kumar B.; Gurjar K.K.; Kumar R.; Kumar V.; Kumar R.
    Decarboxylative A3-coupling of ortho-hydroxybenzaldehydes, secondary amines, and alkynoic acids is performed under catalyst and solvent-free conditions. The developed methodology provided a waste-free method for the synthesis of hydroxylated propargylamines which are versatile precursors for various bioactive heterocyclic scaffolds. The experimental and density functional theory studies revealed that the in situ-formed ortho-quinonoid intermediate (formed from ortho-hydroxybenzaldehyde and amine) undergoes a concerted Eschweiler-Clarke type decarboxylation with alkynoic acids. The synthesized compounds were evaluated for MAO-A, MAO-B, and AChE inhibitory activities as potential drug candidates for the treatment of various neurological disorders. Compound 4f was found to be the most potent and selective MAO-B (high selectivity over MAO-A) and AChE inhibitor in the series with IC50 values of 4.27 ± 0.07 and 0.79 ± 0.03 ?M, respectively.
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    Amido-amine derivative of alginic acid (AmAA) for enhanced adsorption of Pb(II) from aqueous solution
    (Elsevier B.V., 2020) Vaid U.; Mittal S.; Babu J.N.; Kumar R.
    The present work reports the alternate synthesis of amido-amine derivative of alginic acid (AmAA) with high degree of functionalization. The AmAA have been characterized for percentage functionalization, functional group change, surface morphology and thermal decomposition behavior. The results indicate that the amido-amine derivatisation of alginic acid (AA) with >95% functionalization, significantly improves its Pb(II) adsorption efficiency (395.72 mg/g to 535.87 mg/g) over the AA. The equilibrium and kinetic studies showed that Langmuir and Freundlich adsorption isotherm models fitted well to the experimental data, and these followed pseudo-second order kinetic model. The FTIR (Fourier transform infrared spectroscopy) and 13C CP-MAS NMR (Cross-polarization magic angle spinning carbon-13 solid state nuclear magnetic resonance spectroscopy) analysis revealed that Pb(II) binds to the carboxyl group in case of AA and to the carbonyl & amine group in case of AmAA, which leads to increase in its adsorption efficiency. The study concludes that the functionalization of amido-amine on AA improves its adsorptive efficiency for Pb(II) from aqueous medium.
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    Recent advances in decarboxylative C-C bond formation using direct or in situ generated alkenyl acids
    (Taylor and Francis Inc., 2019) Kaur P.; Kumar V.; Kumar R.
    In recent years, the reactions of abundantly available, inexpensive, and structurally diverse alkenyl acids (-C=C-COOH) with C-X (X = halogen) or C-H coupling partner have emerged as vital strategies for the streamlined synthesis of functionalized alkenes with extrusion of innocuous CO2. Various alkenyl acids such as cinnamic acids can act as stable surrogates for the polymerization prone styrenes/olefins, which otherwise need special attention for their handling and storage. Furthermore, cinnamic acids can be easily prepared through various methodologies including Knoevenagel-Doebner (KD) condensation, Heck coupling reaction, etc. Recently, various one-pot tandem methodologies involving the decarboxylative coupling of KD/Heck sequence with C-H or C-X substrate have come into fore. The present review article edifies about the recent advances, scope and limitations for C-C bond formation via (i) direct decarboxylative functionalization of C-X or C-H substrate with alkenyl acids, (ii) tandem one-pot multicomponent decarboxylative approaches (involving in situ generated alkenyl acids) e.g. coupling of KD/Heck sequences with C-X or C-H substrate.
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    Effect of 1-allyl-3-methylimidazoleum bromide on the motional dynamics and thermal stability of horse ferrocytochrome c
    (American Institute of Physics Inc., 2019) Garg M.; Kumari B.; Kumar R.
    The novel green solvent, ionic liquids emerged as potential solvents in executing the various in-vitro protein based applications. In the present study, we investigated the role of 1-allyl-3-methylimidazolium bromide ([Amim]Br) on motional dynamics and thermal stability of ferrocytochrome c (Ferrocyt c) at pH 7.0. Our results revealed that (i) the presence of low concentration of [Amim]Br reduces the levels of thermal motion of the -loop of the native Ferrocyt c (ii) at relatively higher concentrations, the denaturing effect of [Amim]Br increases the thermal motions of the -loop that lead to unfold the proteins, and (iii) [Amim]Br presence in reaction medium decreases the thermal stability of native Ferrocyt c at pH 7.0. � 2019 American Institute of Physics Inc.. All rights reserved.