Chemistry - Research Publications
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Item Recent advances in decarboxylative C-C bond formation using direct or in situ generated alkenyl acids(Taylor and Francis Inc., 2020) 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. � 2019, � 2019 Taylor & Francis.Item Novel Green Approach for Fabrication of Ag2CrO4/TiO2/Au/r-GO Hybrid Biofilm for Visible Light-Driven Photocatalytic Performance(American Chemical Society, 2020) Biswas, R; Mete, S; Mandal, M; Banerjee, B; Singh, H; Ahmed, I; Haldar, K.K.Development of cutting edge materials using a benevolent ecologically cordial methodology is an ideal approach for heterogeneous visible light photocatalysis. A new biogenic photocatalyst was developed by coupling titanium dioxide (TiO2) decorated elongated rhombic shape silver chromate (Ag2CrO4) with gold (Au) and reduced graphene oxide (r-GO) for dye degradation applications under visible light. An ecologically positive methodology was utilized to develop the quaternary Ag2CrO4/TiO2/Au/r-GO nanostructures biofilm with gold and reduced graphene oxide (r-GO) via impregnation and in situ reduction technique in the presence of acacia gum. The structural properties and morphology of the Ag2CrO4/TiO2/Au/r-GO nanostructures were described by several spectroscopic and microscopic methods such as XRD, XPS, ATR-FTIR, Raman spectroscopy, FE-SEM, etc. Alteration with Au and r-GO decreased the band vitality and essentially improved the visible light ingestion of the quaternary Ag2CrO4/TiO2/Au/r-GO composite biofilm photocatalyst and slowed down the recombination process of the photogenerated electrons and holes. To demonstrate how such a unique heterostructured biofilm might produce more outstanding photocatalytic activity, we examined a comparison of the photocatalytic performances of Ag2CrO4/TiO2/Au/r-GO hybrid biofilm with different inner structures. The photocatalytic debasement of MB reached almost 97% within 52 min, and it has been found that the Ag2CrO4/TiO2/Au/r-GO biofilm increased the degradation rate of MB by a factor of 10.8, 6.5, and 3.1 in comparison with exposed Ag2CrO4, Ag2CrO4/TiO2, and Ag2CrO4/TiO2/Au biofilms, individually. Further, the high electron movement capacity of Ag2CrO4/TiO2/Au/r-GO biofilm was explored by photoelectrochemical investigation and TCSPC to comprehend the mechanistic insight of the superior activity of this composite nanostructures under visible light illumination. Hence, the present investigation describes a facile, eco-friendly, and biomimetic approach for the fabrication of Ag2CrO4/TiO2/Au/r-GO biofilm based photocatalyst using acacia gum. Copyright � 2020 American Chemical Society.Item 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.Item 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.Item 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.Item 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.Item Evaluation of heavy metals toxicity in the groundwater of some villages of Sirsa district of Haryana, India(Rasayan Journal of Chemistry, c/o Dr. Pratima Sharma, 2019) Kumar P.; Jain S.; Kumar B.An attempt was made to assess the groundwater quality in some rural parts of Sirsa district of Haryana, India with respect to heavy metals contamination. For this purpose, 23 groundwater samples were collected from the bore wells during pre-monsoon in 2017 from some selected locations in the study area where the groundwater is used for drinking and agricultural activities. The samples have been analyzed for seven heavy metals viz. Mn, As, Zn, Cd, Pb, Cu and Cr using ICP-MS. The results were compared with the BIS standards to assess the suitability of groundwater for drinking. To assess the heavy metal contamination, the heavy metal pollution index (HPI), metal index (MI) and hazard index (HI) was calculated. The groundwater with HI > 1 falls in the high pollution category. In our study, 10 out of 23 samples were not fit to consume by the infants and all the 23 samples were found to be unfit for both the children and the adults. The correlation matrix showed a good correlation of HPI with Mn (r = 0.998), As (r = 0.993), Cu (r = 0.998), Cr (r = 0.998) and with Pb (r = 0.998) whereas the correlation of MI with Mn (r = 0.998), As (r = 0.994), Cu (r = 0.998), Cr (r = 0.999) and with Pb (r = 0.998).Item Seed free high yield gold nanorods synthesis from single precursor gold(I) dithiophosphate complex(John Wiley and Sons Ltd, 2019) Biswas R.; Khirid S.; Saha M.; Liu C.W.; Dhayal R.S.; Haldar K.K.In this work, we demonstrate a simple, one pot and seed free synthetic route for the formation of gold nanorods (Au NRs) via thermal decomposition of gold(I) dithiophosphate {[Au2{S2P(OiPr)2}2]n,} 1 complex as a molecular precursor in presence of 4?-amino-biphenyl-4-carboxylic molecule. Here [Au2{S2P(OiPr)2}2]n, complex functioned as gold (Au) source and 4?-amino-biphenyl-4-carboxylic molecule stabilized gold (Au) nanorods (NRs) through the unidirectional coating of Au surface during its growth in the reaction medium.Item Nonlinear Optical Switching and Enhanced Nonlinear Optical Response of Au–CdSe Heteronanostructures(ACS Publications, 2014) Sreeramulu, V.; Haldar, Krishan Kant; Patra, Amitava; Rao, D. NarayanaThe metal–semiconductor heterostructures have recently emerged as a new class of functional materials for their potential applications due to plasmon-exciton interactions. Here, we demonstrate the nonlinear optical switching and enhanced nonlinear optical response of Au–CdSe heterostructures. The nonlinear optical properties of CdSe quantum dots and Au–CdSe heteronanostructures are investigated by using a Z-scan technique at 532 nm picosecond laser pulses, and 800 nm femtosecond laser pulses. Interestingly, we observe switching behavior from saturable absorption (SA) to reverse saturable absorption (RSA) with increasing laser intensity. The effective two-photon absorption cross section (σeff) of Au–CdSe heteronanostructures is greatly enhanced which is attributed to charge transfer between CdSe and Au nanoparticles. The nonlinear refraction changes its sign from positive to negative nonlinearity at higher intensities for Au–CdSe heterostructures. Third order nonlinear optical susceptibility is being measured by using the DFWM technique at 532 nm. Similar switching behavior is observed in Au–CdSe heteronanostructures at nonresonant excitations (800 nm), where a CdSe quantum dot shows reverse saturable absorption behavior attributed to the two-photon absorption. The optical switching behavior of these heterostructures could play a potential role in photonics and optoelectronic applications.Item Use of agricultural solid wastes as adsorbent(Material Research Forum LLC, 2018) Nag, Shilpa; Bhardwaj, Akanksha; Pandey,Puneeta; Arora, Meenu; J. N. Babu