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Articles 1 - 11 of 11
Full-Text Articles in Physical Sciences and Mathematics
Synthesis And Reductive Chemistry Of Bimetallic And Trimetallic Rare-Earth Metallocene Hydrides With (C5h4sime3)1− Ligands, Megan T. Dumas, Guo P. Chen, Jasper Y. Hu, Mitchell A. Nascimento, Jeremy M. Rawson, Joseph W. Ziller, Filipp Furche, William J. Evans
Synthesis And Reductive Chemistry Of Bimetallic And Trimetallic Rare-Earth Metallocene Hydrides With (C5h4sime3)1− Ligands, Megan T. Dumas, Guo P. Chen, Jasper Y. Hu, Mitchell A. Nascimento, Jeremy M. Rawson, Joseph W. Ziller, Filipp Furche, William J. Evans
Chemistry and Biochemistry Publications
The reductive chemistry of [Cp'2Ln(μ–H)(THF)x]y [Ln = Y, Dy, Tb; Cp' = (C5H4SiMe3)1−; x = 2, 0 and y = 2, 3] was examined to determine if these hydrides would be viable precursors for 4fn5d1 Ln2+ ions that could form 5d1-5d1 metal–metal bonded complexes. The hydrides were prepared by reaction of the chlorides, [Cp'2Ln(μ–Cl)]2, 1-Ln, with allylmagnesium chloride to form the allyl complexes, [Cp'2Y(η3–C3H5 …
Structural Variations In The Dithiadiazolyl Radicals P-Roc6f4cnssn (R = Me, Et, Npr, Nbu): A Case Study Of Reversible And Irreversible Phase Transitions In P-Etoc6f4cnssn, Yassine Beldjoudi, Rui Sun, Ana Arauzo, Javier Campo, Robert J. Less, Jeremy M. Rawson
Structural Variations In The Dithiadiazolyl Radicals P-Roc6f4cnssn (R = Me, Et, Npr, Nbu): A Case Study Of Reversible And Irreversible Phase Transitions In P-Etoc6f4cnssn, Yassine Beldjoudi, Rui Sun, Ana Arauzo, Javier Campo, Robert J. Less, Jeremy M. Rawson
Chemistry and Biochemistry Publications
The 4ʹ-alkoxy-tetrafluorophenyl dithiadiazolyls, ROC6F4CNSSN [R = Me (1), Et (2), nPr (3), nBu(4)] all adopt cis-oid dimers in the solid state. The methoxy derivative 1 adopts a π-stacked AA’AA’ motif whereas propoxy (3) and butoxy (4) derivatives exhibit an AA’BB’ stacking. The ethoxy derivative (2) is polymorphic. The α-phase (2α) adopts an AA’BB’ motif comparable with 3 and 4, whereas 2β and 2γ are reminiscent of 1 but combine a mixture of both monomers and dimers in the solid state. The …
Inclusion Of A Dithiadiazolyl Radical In A Seemingly Non-Porous Solid, Varvara I. Nikolayenko,, Leonard J. Barbour, Ana Arauzo, Javier Campo, Jeremy M. Rawson, Delia A. Haynes
Inclusion Of A Dithiadiazolyl Radical In A Seemingly Non-Porous Solid, Varvara I. Nikolayenko,, Leonard J. Barbour, Ana Arauzo, Javier Campo, Jeremy M. Rawson, Delia A. Haynes
Chemistry and Biochemistry Publications
Inclusion of the dithiadiazolyl radical PhCNSSN• into the dynamically porous metallocycle [Cu2(L1)2Cl4], where L1 is the bidentate ligand 1,3-bis(imidazol-1-ylmethyl)-2,4,6- trimethylbenzene, has been achieved by gas phase diffusion. Single crystal X-ray diffraction, powder X-ray diffraction, UV-visible spectroscopy, EPR and SQUID magnetometry studies confirm inclusion of the radical into this seemingly non-porous material, and illustrate the presence of antiferromagnetic coupling between the paramagnetic host and guest species. The radical guest is readily released by heating or by the addition of solvent (CH2Cl2).
Nicholas Reactions Of Alkynyl- And Alkenyltrifluoroborates, Brent St. Onge, James R. Green
Nicholas Reactions Of Alkynyl- And Alkenyltrifluoroborates, Brent St. Onge, James R. Green
Chemistry and Biochemistry Publications
The Lewis acid mediated Nicholas reaction of potassium alkynyltrifluoroborates and propargyl acetate- hexacarbonyldicobalt complexes affords 1,4-diyne dicobalt hexacarbonyl complexes in good yields. The analogous Nicholas reactions of potassium alkenyltrifluoroborates give 1,3-enyne dicobalt hexacarbonyl complexes in most cases, although the initial site of reaction can vary. Potassium vinyltrifluoroborate itself affords alkynylcyclopropane complexes.
Computational Insights Into Substrate Binding And Catalytic Mechanism Of The Glutaminase Domain Of Glucosamine-6-Phosphate Synthase (Glms), Wanlei Wei, Gerald Monard, James Gauld
Computational Insights Into Substrate Binding And Catalytic Mechanism Of The Glutaminase Domain Of Glucosamine-6-Phosphate Synthase (Glms), Wanlei Wei, Gerald Monard, James Gauld
Chemistry and Biochemistry Publications
Glucosamine-6-phosphate synthase (GlmS) is a key enzyme in the biosynthesis of hexosamine across a variety of species including Escherichia coli, fungi, and humans. In particular, its glutaminase domain catalyzes the conversion of glutamine to glutamic acid with the release of ammonia. A catalytically important cysteinyl (Cys1) has been suggested to act as the mechanistic nucleophile after being activated by the N-terminal amine of the glutaminase domain (i.e., its own α-amine). Using molecular dynamics (MD) and quantum mechanics/molecular mechanics (QM/MM) computational methods, we have investigated the active site of the glutaminase domain, the protonation state of its N-terminal amine, substrate binding, …
Synthesis Of Bis(Trithio)Phosphines By Oxidative Transfer Of Phosphorus(I), Stephanie C. Kosnik, Maxemilian C. Nascimento, Jeremy M. Rawson, Charles L.B. Macdonald
Synthesis Of Bis(Trithio)Phosphines By Oxidative Transfer Of Phosphorus(I), Stephanie C. Kosnik, Maxemilian C. Nascimento, Jeremy M. Rawson, Charles L.B. Macdonald
Chemistry and Biochemistry Publications
The synthesis of novel trithiobisphosphines is achieved by oxidative addition of tetrathiocins to the phosphorus(I) reagent [PIdppe][Br] in good yields under ambient conditions. These trithiobisphosphines and the related intermediate diphosphine species are characterized by X-ray diffraction and multinuclear NMR and a mechanism is proposed for the formation of these molecules.
1H Nmr Shows Slow Phospholipid Flip-Flop In Gel And Fluid Bilayers, Drew Marquardt, Frederick A. Heberle, Tatiana Miti, Barbara Eicher, Erwin London, John Katsaras, Georg Pabst
1H Nmr Shows Slow Phospholipid Flip-Flop In Gel And Fluid Bilayers, Drew Marquardt, Frederick A. Heberle, Tatiana Miti, Barbara Eicher, Erwin London, John Katsaras, Georg Pabst
Chemistry and Biochemistry Publications
We measured the transbilayer diffusion of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) in large unilamellar vesicles, in both the gel (Lβ′) and fluid (Lα) phases. The choline resonance of headgroup-protiated DPPC exchanged into the outer leaflet of headgroup-deuterated DPPC-d13 vesicles was monitored using 1H NMR spectroscopy, coupled with the addition of a paramagnetic shift reagent. This allowed us to distinguish between the inner and outer bilayer leaflet of DPPC, to determine the flip-flop rate as a function of temperature. Flip-flop of fluid-phase DPPC exhibited Arrhenius kinetics, from which we determined an activation energy of 122 kJ mol-1. In gel-phase DPPC vesicles, flip-flop was not …
Importance Of The Inter-Electrode Distance For The Electrochemical Synthesis Of Magnetite Nanoparticles: Synthesis, Characterization, Computational Modelling, And Cytotoxicity, Seyedeh Maryamdokht Taimoory, John F. Trant, Abbas Rahdar, Mousa Aliahmad, Fardin Sadeghfar, Mahmoud Hashemzaei
Importance Of The Inter-Electrode Distance For The Electrochemical Synthesis Of Magnetite Nanoparticles: Synthesis, Characterization, Computational Modelling, And Cytotoxicity, Seyedeh Maryamdokht Taimoory, John F. Trant, Abbas Rahdar, Mousa Aliahmad, Fardin Sadeghfar, Mahmoud Hashemzaei
Chemistry and Biochemistry Publications
Magnetite (Fe3O4) nanoparticles, are promising inorganic nanomaterials for future biomedical applications due to their low toxicity and unique magnetic properties. However, the synthesis of these particles can often be expensive, energy intensive, and non-scalable, requiring the addition of surfactants to stabilize the material to control the particle size and avoid agglomeration. We wish to report a simple, green, surfactant-free electrochemical synthesis of these materials using a closed aqueous system at ambient temperature. Particle diameter, between 19 and 33 nm, was controlled by simply modifying the distance between the electrodes. These magnetite nanoparticles were then fully characterized using both spectroscopy and …
Endo -/ Exo - And Halogen-Bonded Complexes Of Conformationally Rigid C -Ethyl-2-Bromoresorcinarene And Aromatic N -Oxides, Rakesh Puttreddy, Ngong Kodiah Beyeh, Robin H.A. Ras, John F. Trant, Kari Rissanen
Endo -/ Exo - And Halogen-Bonded Complexes Of Conformationally Rigid C -Ethyl-2-Bromoresorcinarene And Aromatic N -Oxides, Rakesh Puttreddy, Ngong Kodiah Beyeh, Robin H.A. Ras, John F. Trant, Kari Rissanen
Chemistry and Biochemistry Publications
The host-guest complexes of conformationally rigid C-ethyl-2-bromoresorcinarene with aromatic N-oxides were studied using single crystal X-ray crystallography. Unlike that of the conformationally more flexible C-ethyl-2-methylresorcinarene, the C-ethyl-2-bromoresorcinarene cavity forms endo-complexes only with the small pyridine-N-oxides, such as pyridine N-oxide, 2-methyl-, 3-methyl- and 4-methylpyrdine N-oxide, and quinoline N-oxide. The larger 2,4,6-trimethylpyridine, 4-phenylpyridine and isoquinoline N-oxide, and 4,4-bipyridine N,N′-dioxide and 1,3-bis(4-pyridyl)propane N,N′-dioxide do not fit into the host cavity. Instead endo-acetone complexes are formed. Remarkably, differing from the anti-gauche endo-complex with C-ethyl-2-methylresorcinarene, the flexible 1,3-bis(4-pyridyl)propane N,N′-dioxide guest forms an anti-anti exo-complex with C-ethyl-2-bromoresorcinarene. The endo- and exo-complexes of C-ethyl-2-bromoresorcinarene and studied N-oxides …
Halogen-Bonded Solvates Of Tetrahaloethynyl Cavitands, Lotta Turunen, Fangfang Pan, Ngong Kodiah Beyeh, Mario Cetina, John F. Trant, Robin H.A. Ras, Kari Rissanen
Halogen-Bonded Solvates Of Tetrahaloethynyl Cavitands, Lotta Turunen, Fangfang Pan, Ngong Kodiah Beyeh, Mario Cetina, John F. Trant, Robin H.A. Ras, Kari Rissanen
Chemistry and Biochemistry Publications
The formation and structures of halogen-bonded solvates of three different tetrahaloethynyl cavitands with acetone, chloroform, acetonitrile, DMF and DMSO were prepared and investigated. The inclusion and host-guest behaviour of the resorcinarene cavitands was found to be highly dependent on the flexibility of the ethylene-bridging unit.
Joint Small-Angle X-Ray And Neutron Scattering Data Analysis Of Asymmetric Lipid Vesicles, Barbara Eicher, Frederick A. Heberle, Drew Marquardt, Gerald N. Rechberger, John Katsaras, Georg Pabst
Joint Small-Angle X-Ray And Neutron Scattering Data Analysis Of Asymmetric Lipid Vesicles, Barbara Eicher, Frederick A. Heberle, Drew Marquardt, Gerald N. Rechberger, John Katsaras, Georg Pabst
Chemistry and Biochemistry Publications
Low- and high-resolution models describing the internal transbilayer structure of asymmetric lipid vesicles have been developed. These models can be used for the joint analysis of small-angle neutron and X-ray scattering data. The models describe the underlying scattering length density/electron density profiles either in terms of slabs or through the so-called scattering density profile, previously applied to symmetric lipid vesicles. Both models yield structural details of asymmetric membranes, such as the individual area per lipid, and the hydrocarbon thickness of the inner and outer bilayer leaflets. The scattering density profile model, however, comes at a cost of increased computational effort …