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Item Heavy Metal Ion Sensing Using Ultrathin Langmuir–Schaefer Film of Tetraphenylporphyrin Molecule(IEEE, 2019-12) Manjuladevi, V.; Gupta, Karunesh Kumar; Kumar, Dalip; Gupta, Raj KumarThe exciting properties of porphyrin molecules can be employed for several applications like sensing, catalysis, photovoltaics and energy related fields. The assemblies of the molecules at interfaces can give rise to some unique physicochemical properties which can enhance the device performance. In this article, we report our studies on heavy metal ion sensing in aqueous medium using ultrathin film of tetraphenylporphyrin (TPP) molecules. The TPP molecules were synthesized and used for forming Langmuir monolayer at the air-water interface. The monolayer was transferred onto solid substrates by Langmuir-Schaefer (LS) method at different target surface pressure of deposition (πT). The morphological analysis of the films indicated supramolecular assembly of the molecules in the LS film deposited at πT = 30 mN/m. The LS films of TPP molecules were employed for sensing heavy metal cations viz. Pb 2+ , Hg 2+ , Co 2+ and Cd 2+ from the aqueous medium by measuring piezoresponse from a quartz crystal microbalance. The sensing performance was found to be the best with LS film deposited at πT = 30 mN/m. The sensitivity-towards Pb 2+ ion is found to be the highest. The sensing of the heavy metal cations using randomly oriented TPP molecules in spin coated thin film was found to be much inferior as compared to that of LS films of the molecule. The enhanced sensing performance by the LS film of TPP molecules may be attributed to the supramolecular assembly of the molecules. We report that the interference of the sensing measurement for the recognition of Cd 2+ and Pb 2+ ions is least and thus these species can be detected selectively with less errors. The cation species recognition features obtained from scanning electron microscope images and Raman spectroscopy were found to be remarkably different and therefore these cationic heavy metal species can be selectively detected using the LS film of TPP.Item Synthesis, evaluation and molecular modelling studies of 2-(carbazol-3-yl)-2-oxoacetamide analogues as a new class of potential pancreatic lipase inhibitors(Elsevier, 2017-01) Kumar, Dalip; Paul, Atish TulshiramA series of twenty four 2-(carbazol-3-yl)-2-oxoacetamide analogues were synthesized, characterized and evaluated for their pancreatic lipase (PL) inhibitory activity. Porcine PL was used against 4-nitrophenyl butyrate (method A) and tributyrin (methods B and C) as substrates during the PL inhibition assay. Compounds 7e, 7f and 7p exhibited potential PL inhibitory activity (IC50 values of 6.31, 8.72 and 9.58 μM, respectively in method A; and Xi50 of 21.85, 21.94 and 26.2, respectively in method B). Further, inhibition kinetics of 7e, 7f and 7p against PL, using method A, revealed their competitive nature of inhibition. A comparison of the inhibition profiles of the top three compounds in methods B and C, provided a preliminary idea of covalent bonding of the compounds with Ser 152 of PL. Molecular docking studies of the compounds 7a–x into the active site of human PL (PDB ID: 1LPB) was in agreement with the in vitro results, and highlighted probable covalent bond formation with Ser 152 apart from hydrophobic interactions with the lid domain. Molecular dynamics simulation of 7e complexed with PL, further confirmed the role of aromatic groups in stabilising the ligand (RMSD ⩽ 4 Å). The present study led to the identification of 2-(carbazol-3-yl)-2-oxoacetamide analogues 7a–x as a new class of potential PL inhibitors.Item Metal-free regioselective formation of C–N and C–O bonds with the utilization of diaryliodonium salts in water: facile synthesis of N-arylquinolones and aryloxyquinolines(RSC, 2017) Kumar, Dalip; Kumar, IndreshRegioselective construction of crucial C–N and C–O bonds leading to N-arylquinolones and aryloxyquinolines has been accomplished by employing easily accessible diaryliodonium salts and quinolones in water under metal- and ligand-free conditions. This operationally simple strategy is significant due to mild reaction conditions, high product yields, recyclability of released iodoarenes and scalability to the gram level. The practical utility of the developed protocol was proved by the arylation of medicinally important heterocycles like acridin-9(10H)-one, 3-methylquinoxalin-2(1H)-one and 1H-benzo[d]imidazol-2(3H)-one.Item Reaction of Aryl and Heterocyclylhydrazines with 2-Methylchromone: Structural Investigation of the Products(Taylor & Francis, 1996) Kumar, DalipReaction of 2-methylchromone (2) with phenylhydrazine provides 3-methyl-5-(o-hydroxyphenyl)-1-phenylpyrazole (6) as a major product. In contrast under similar conditions, heterocyclylhydrazines (8a-c) yield exclusively 5-ethyl-3-(o-hydroxyphenyl)-1-heterocyclylpyrazoles (9a-c). The structural assignments are based on an unambiguous synthesis and an analysis of NMR (1H & 13C) spectral data.Item Conformation and ortho steric effects in a series of 2-(pyrazol-1-yl)quinolines(Wiley, 1996-04) Kumar, DalipNine 2-(pyrazol-1-yl)-4-methylquinolines bearing substituents on the pyrazole 3- or 5-positions (H, Me, Et, i-Pr, t-Bu) were regioselectively synthesized either using the direct condensation of 2-chloro-4-methylquinoline and sodium salt of 3(5)-substituted pyrazoles or by treatment of 2-hydrazino-4-methylquinoline with an appropriate β-ketoaldehyde. The 1H and 13C chemical shifts were discussed taking into account the preferred conformation about the C-2-N-1′ bond as calculated by the AM1 Hamiltonian. It appears that 5-ethyl and 5-isopropyl substituted derivatives present short C-H-N-1 interactions. Ortho steric effects appear to be responsible for these conformations.Item Hypervalent Iodine Oxidation of 1, 3, 5-Trisubstituted Pyrazolines: A Facile Synthesis of 1,3,5-Trisubstituted Pyrazoles(Taylor & Francis, 1997) Kumar, Dalip1, 3, 5-Trisubstituted pyrazolines (1a–i) undergo facile oxidation to the corresponding pyrazoles (2a–i) in the presence of iodobenzene diacetate.Item A Facile Synthesis of 5-Methyl-1-(phenyl/heterocyclyl)-4-trifluoroacetylpyrazoles(RSC, 1997) Kumar, DalipTreatment of substituted hydrazines (2a–d) with 3-acetyl-4-ethoxy-1,1,1-trifluorobut-3-en-2-one (1) yields the title compounds (3a–d) whereas methylhydrazine on similar treatment gives 4-acetyl-1-methyl-3-trifluoromethylpyrazoleItem Hypervalent iodine oxidation of 2-aryl-1,2,3,4-tetrahydro-4-quinolones: An expedient route to naturally occurring 4-alkoxy-2-arylquinolines(Elsiever, 1998-12-10) Kumar, DalipEasily accessible 2-aryl-1,2,3,4-tetrahydro-4-quinolones are readily oxidized to the corresponding 4-alkoxy-2-arylquinolines using a relatively safe hypervalent iodine reagent, [hydroxy (tosyloxy)iodo]benzene (HTIB), in high yields, thus providing a concise route to an important class of naturally occurring alkaloids. 2-Aryl-1,2,3,4-tetrahydro-4-quinolones are readily oxidized to the corresponding 4-alkoxy-2-arylquinolines by [hydroxy(tosyloxy)iodo]benzene(HTIB), thus providing a concise route to a class of naturally occurring alkaloids.Item Manganese triacetate oxidation of phenolic schiffs bases: Synthesis of 2-arylbenzoxazoles(Wiley, 2009-03-12) Kumar, DalipA concise synthesis of 2-arylbenzoxazoles, 5a-f, is described that occurs via the oxidative cyclization of Schiff's bases, 1a-f, using relatively benign reagent, manganese triacetate.Item A facile one-pot synthesis of 2,5-disubstituted oxazoles using iodobenzene diacetate(Wiley, 2009-03-12) Kumar, DalipA facile one-pot synthesis of oxazoles 1a-h is described that utilizes readily available aromatic α-methyl ketones and a safe hypervalent iodine reagent, iodobenzene diacetate.