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Articles 1 - 7 of 7
Full-Text Articles in Physical Sciences and Mathematics
Facile Synthesis Of 1-Alkoxy-1h-Benzo- And 7-Azabenzotriazoles From Peptide Coupling Agents, Mechanistic Studies, And Synthetic Applications, Mahesh K. Lakshman, Manish K. Singh, Mukesh Kumar, Raghu Ram Chamala, Vijayender R. Yedulla, Domenick Wagner, Evan Leung, Lijia Yang, Asha Matin, Sadia Ahmad
Facile Synthesis Of 1-Alkoxy-1h-Benzo- And 7-Azabenzotriazoles From Peptide Coupling Agents, Mechanistic Studies, And Synthetic Applications, Mahesh K. Lakshman, Manish K. Singh, Mukesh Kumar, Raghu Ram Chamala, Vijayender R. Yedulla, Domenick Wagner, Evan Leung, Lijia Yang, Asha Matin, Sadia Ahmad
Publications and Research
(1H-Benzo[d][1,2,3]triazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (BOP), 1H-benzo[d][1,2,3]triazol-1-yl 4-methylbenzenesulfonate (Bt-OTs), and 3H-[1,2,3]triazolo[4,5-b]pyridine-3-yl 4-methylbenzenesulfonate (At-OTs) are classically utilized in peptide synthesis for amide-bond formation. However, a previously undescribed reaction of these compounds with alcohols in the presence of a base, leads to 1-alkoxy-1H-benzo- (Bt-OR) and 7-azabenzotriazoles (At-OR). Although BOP undergoes reactions with alcohols to furnish 1-alkoxy-1H-benzotriazoles, Bt-OTs proved to be superior. Both, primary and secondary alcohols undergo reaction under generally mild reaction conditions. Correspondingly, 1-alkoxy-1H-7-azabenzotriazoles were synthesized from At-OTs. Mechanistically, there are three pathways by which these peptide-coupling agents can react with alcohols. From 31P{1H}, [18O]-labeling, and other chemical experiments, phosphonium and tosylate derivatives of …
Synergism Between Airborne Singlet Oxygen And A Trisubstituted Olefin Sulfonate For The Inactivation Of Bacteria, Rajib Choudhury, Alexander Greer
Synergism Between Airborne Singlet Oxygen And A Trisubstituted Olefin Sulfonate For The Inactivation Of Bacteria, Rajib Choudhury, Alexander Greer
Publications and Research
The reactivity of a trisubstituted alkene surfactant (8-methylnon-7-ene-1 sulfonate, 1) to airborne singlet oxygen in a solution containing E. coli was examined. Surfactant 1 was prepared by a Strecker-type reaction of 9-bromo-2-methylnon-2-ene with sodium sulfite. Submicellar concentrations of 1 were used that reacted with singlet oxygen by an “ene” reaction to yield two hydroperoxides (7-hydroperoxy-8-methylnon-8-ene-1 sulfonate and (E)-8-hydroperoxy-8-methylnon-6-ene-1 sulfonate) in a 4:1 ratio. Exchanging the H2O solution for D2O where the lifetime of solution-phase singlet oxygen increases by 20-fold led to an ∼2-fold increase in the yield of hydroperoxides pointing to surface activity …
Capping Amyloid Β‑Sheets Of The Tau-Amyloid Structure Vqivyk With Hexapeptides Designed To Arrest Growth. An Oniom And Density Functional Theory Study, Joshua A. Plumley, Jorge Ali-Torres, Gabor Pohl, J. J. Dannenberg
Capping Amyloid Β‑Sheets Of The Tau-Amyloid Structure Vqivyk With Hexapeptides Designed To Arrest Growth. An Oniom And Density Functional Theory Study, Joshua A. Plumley, Jorge Ali-Torres, Gabor Pohl, J. J. Dannenberg
Publications and Research
We present ONIOM calculations using density functional theory (DFT) as the high and AM1 as the medium level that explore the abilities of different hexapeptide sequences to terminate the growth of a model for the tau-amyloid implicated in Alzheimer’s disease. We delineate and explore several design principles (H-bonding in the side chains, using antiparallel interactions on the growing edge of a parallel sheet, using all-D residues to form rippled interactions at the edge of the sheet, and replacing the H-bond donor N−H’s that inhibit further growth) that can be used individually and in combination to design such peptides that will …
Intramolecular Nitrogen Delivery For The Synthesis Of C-Glycosphingolipids. Application To The C-Glycoside Of The Immunostimulant Krn7000, Ahmad Sabri Altiti, David R. Mootoo
Intramolecular Nitrogen Delivery For The Synthesis Of C-Glycosphingolipids. Application To The C-Glycoside Of The Immunostimulant Krn7000, Ahmad Sabri Altiti, David R. Mootoo
Publications and Research
The key reaction in this approach to C-glycosphingolipids is the stereoselective iodocyclization of a sugar-linked homoallylic carbonimidothioate. E and Z reaction substrates were assembled in a convergent fashion via an alkene metathesis strategy and exhibited the same alkene facial selectivity in the iodocyclization irrespective of alkene geometry, although the E alkene was found to be less reactive.
A Review Of Air–Ice Chemical And Physical Interactions (Aici): Liquids, Quasi-Liquids, And Solids In Snow, T. Bartels-Rausch, H-W Jacobi, T. F. Kahan, J. L. Thomas, E. S. Thomson, J. P. D. Abbatt, M. Ammann, J. R. Blackford, H. Bluhm, Chris Boxe, F. Domine, M. M. Frey, I. Gladich, M. I. Guzmán, D. Heger, Th. Huthwelker, P. Klán, W. F. Kuhs, M. H. Kuo, S. Maus, S. G. Moussa, V. F. Mcneill, J. T. Newberg, J. B. C. Pettersson, M. Roeselová, J. R. Sodeau
A Review Of Air–Ice Chemical And Physical Interactions (Aici): Liquids, Quasi-Liquids, And Solids In Snow, T. Bartels-Rausch, H-W Jacobi, T. F. Kahan, J. L. Thomas, E. S. Thomson, J. P. D. Abbatt, M. Ammann, J. R. Blackford, H. Bluhm, Chris Boxe, F. Domine, M. M. Frey, I. Gladich, M. I. Guzmán, D. Heger, Th. Huthwelker, P. Klán, W. F. Kuhs, M. H. Kuo, S. Maus, S. G. Moussa, V. F. Mcneill, J. T. Newberg, J. B. C. Pettersson, M. Roeselová, J. R. Sodeau
Publications and Research
Snow in the environment acts as a host to rich chemistry and provides a matrix for physical exchange of contaminants within the ecosystem. The goal of this review is to summarise the current state of knowledge of physical processes and chemical reactivity in surface snow with relevance to polar regions. It focuses on a description of impurities in distinct compartments present in surface snow, such as snow crystals, grain boundaries, crystal surfaces, and liquid parts. It emphasises the microscopic description of the ice surface and its link with the environment. Distinct differences between the disordered air–ice interface, often termed quasi-liquid …
Deconstructing A Plant Macromolecular Assembly: Chemical Architecture, Molecular Flexibility, And Mechanical Performance Of Natural And Engineered Potato Suberins, Olga Serra, Subhasish Chatterjee, Merce Figueras, Marisa Molinas, Ruth E. Stark
Deconstructing A Plant Macromolecular Assembly: Chemical Architecture, Molecular Flexibility, And Mechanical Performance Of Natural And Engineered Potato Suberins, Olga Serra, Subhasish Chatterjee, Merce Figueras, Marisa Molinas, Ruth E. Stark
Publications and Research
Periderms present in plant barks are essential protective barriers to water diffusion, mechanical breakdown, and pathogenic invasion. They consist of densely packed layers of dead cells with cell walls that are embedded with suberin. Understanding the interplay of molecular structure, dynamics, and biomechanics in these cell wall-associated insoluble amorphous polymeric assemblies presents substantial investigative challenges. We report solid-state NMR coordinated with FT-IR and tensile strength measurements for periderms from native and wound-healing potatoes and from potatoes with genetically modified suberins. The analyses include the intact suberin aromatic; aliphatic polymer and cell-wall polysaccharides, previously reported soluble depolymerized transmethylation products, and undegraded …
Cyclic Phosphonium Ionic Liquids, Sharon I. Lall-Ramnarine, Joshua A. Mukhlall, James F. Wishart, Robert R. Engel, Alicia R. Romeo, Masao Gohdo, Sharon Ramati, Marc B. Berman, Sophia N. Suarez
Cyclic Phosphonium Ionic Liquids, Sharon I. Lall-Ramnarine, Joshua A. Mukhlall, James F. Wishart, Robert R. Engel, Alicia R. Romeo, Masao Gohdo, Sharon Ramati, Marc B. Berman, Sophia N. Suarez
Publications and Research
Ionic liquids (ILs) incorporating cyclic phosphonium cations are a novel category of materials. We report here on the synthesis and characterization of four new cyclic phosphonium bis(trifluoromethylsulfonyl)amide ILs with aliphatic and aromatic pendant groups. In addition to the syntheses of these novel materials, we report on a comparison of their properties with their ammonium congeners. These exemplars are slightly less conductive and have slightly smaller self-diffusion coefficients than their cyclic ammonium congeners.