Read by QxMD icon Read

Solid state NMR

Martin Heberle, Stefanie Tschierlei, Nils Rockstroh, Mark Ringenberg, Wolfgang Frey, Henrik Junge, Matthias Beller, Stefan Lochbrunner, Michael Karnahl
A series of heteroleptic copper(I) photosensitizers of the type [(P^P)Cu(N^N)]+ with an extended π-system in the backbone of the diimine ligand have been prepared. The structures of all complexes are completely characterized by NMR spectroscopy, mass spectrometry and X-ray crystallography. These novel photosensitizers were assessed with respect to the photocatalytic reduction of protons in the presence of triethylamine and [Fe3(CO)12]. While the solid state structures and computational results show no significant impact of the π-extension on the structural properties decreased activities were observed...
October 21, 2016: Chemistry: a European Journal
Hongwei Yao, Myungwoon Lee, Shu Y Liao, Mei Hong
The fusion peptide (FP) and transmembrane domain (TMD) of viral fusion proteins play important roles during virus-cell membrane fusion, by inducing membrane curvature and transient dehydration. The structure of the water-soluble ectodomain of viral fusion proteins has been extensively studied crystallographically, but the structures of the FP and TMD bound to phospholipid membranes are not well understood. We recently investigated the conformations and lipid interactions of the separate FP and TMD peptides of the parainfluenza virus 5 (PIV5) fusion protein F using solid-state NMR...
October 21, 2016: Biochemistry
Alexander S Falk, Ansgar B Siemer
Several amyloid fibrils have cores framed by highly dynamic, intrinsically disordered, domains that can play important roles for function and toxicity. To study these domains in detail using solid-state NMR spectroscopy, site-specific resonance assignments are required. Although the rapid dynamics of these domains lead to considerable averaging of orientation-dependent NMR interactions and thereby line-narrowing, the proton linewidths observed in these samples is far larger than what is regularly observed in solution...
October 20, 2016: Journal of Biomolecular NMR
Jean-Marie E P Cols, Cameron E Taylor, Kevin J Gagnon, Simon J Teat, Ruaraidh D McIntosh
The synthesis and full characterisation of four discrete tetrametallic titanium complexes is reported. These well-defined compounds are isostructural in the solid state and share the same general formula: Ti4(μ-O)2L4 (L = 1, 2, 3 or 4). Using a combination of NMR techniques the complexes are found to be stable in solution, even at elevated temperatures. Further studies show that the carboxylate moieties of the supporting amine bis(phenolate) ligands can be displaced by a more strongly coordinating solvent...
October 21, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Sujin Seo, Huiyeong Ju, Seulgi Kim, In-Hyeok Park, Eunji Lee, Shim Sung Lee
Homo- and heteronuclear group 12 metal (Zn(2+), Cd(2+), and Hg(2+)) complexes 1-6 containing a newly designed 18-membered N2O2S2 macrocycle incorporating two pyridine subunits (L) were prepared and structurally characterized. The individual complexes isolated exhibit unusual stoichiometries, geometries, oxidation states, and structural topologies and include an infinite mercurous complex and a heteronuclear dumbbell-shaped complex. Both the Zn(II) complex [Zn(L)][ZnBr4] (1) and the Cd(II) complex [Cd(L)Br2] (2) are mononuclear, with the metal ion located inside the macrocyclic cavity...
October 20, 2016: Inorganic Chemistry
Oleg M Michurin, Sergii Afonin, Marina Berditsch, Constantin G Daniliuc, Anne S Ulrich, Igor V Komarov, Dmytro S Radchenko
Conformationally constrained non-racemizing trifluoromethyl-substituted lysine isosteres [(E)- and (Z)-TCBLys] with charged side chains are presented as a new type of (19) F-NMR labels for peptide studies. Design of the labels, their synthesis, incorporation into peptides and experimental demonstration of their application for solid state NMR studies of membrane-active peptides are described. A series of fluorine-labeled analogues of the helical amphipathic antimicrobial peptide PGLa(Nle) was obtained, in which different lysine residues in the original peptide sequence were replaced, one at a time, by either (E)- or (Z)-TCBLys...
October 20, 2016: Angewandte Chemie
Matthias Lehmann, Philipp Maier, Matthias Grüne, Markus Hügel
The molecular design of crowded hexasubstituted star mesogens based on a benzene core and alternating substitution with oligo(phenylenevinylene) arms and aryl units generates free space between the conjugated arm scaffolds. Various arylcarboxy building blocks, decorated with alkoxy chains have been incorporated in the void by mixing, hydrogen bonding or covalent bonds to the aryl groups. The mesogens assemble in columnar stacks ranging from soft crystals to rectangular and hexagonal columnar liquid crystals, revealed by polarized optical microscopy, differential scanning calorimetry, X-ray scattering and modelling...
October 20, 2016: Chemistry: a European Journal
Han-Xiao Wang, Shu-Zhen Hu, Qiang Shi, Chuan-Feng Chen
With an expanded electron-rich cavity and a fixed conformation, macrocycle H was found to encapsulate π-extended viologens G1-G4 to form the first case of pseudo[3]rotaxanes based on oxacalixarenes. The complexation was investigated in detail both in solution and in the solid state using NMR spectroscopy and X-ray crystallography. Due to the three-dimensional nonsymmetric structure of H, three orientational isomers of the pseudorotaxanes could be expected theoretically. However, as the crystal structure analysis revealed, only one of the three isomers was obtained with either G1 or G3...
October 20, 2016: Organic & Biomolecular Chemistry
Yuanrong Xin, Junji Sakamoto, André J van der Vlies, Urara Hasegawa, Hiroshi Uyama
This data article provides supplementary figures to the research article entitled, "Phase separation approach to a reactive polycarbonate monolith for "click" modifications" (Xin et al., Polymer, 2015, doi:10.1016/j.polymer.2015.04.008). Here, the nitrogen adsorption/desorption isotherms of the prepared porous polycarbonate monolith are shown to classify its inner structure and calculate the specific surface area. The monoliths were modified by using the thiol-ene click chemistry and the olefin metathesis, which was examined by contact angle measurements, FT-IR, solid state (13)C NMR spectroscopy as well as thermogravimetric analysis...
June 2016: Data in Brief
Stephan Ingmar Brückner, Sergii Donets, Arezoo Dianat, Manfred Bobeth, Rafael Gutierrez, Gianaurelio Cuniberti, Eike Brunner
Understanding the molecular interactions between inorganic phases such as silica and organic material is fundamental for chromatographic applications, for tailoring silica-enzyme interactions, and for elucidating the mechanisms of biomineralization. The formation, structure, and properties of the organic/inorganic interface is crucial in this context. Here, we investigate the interaction of selectively (13)C-labeled choline with (29)Si-labeled monosilicic acid/silica at the molecular level. Silica/choline nanocomposites were analyzed by solid-state NMR spectroscopy in combination with extended molecular dynamics (MD) simulations to understand the silica/organic interface...
October 19, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Dipankar Sahoo, Mihai Peterca, Emad Aqad, Benjamin E Partridge, Paul A Heiney, Robert Graf, Hans W Spiess, Xiangbing Zeng, Virgil Percec
Perylene bisimide derivatives (PBIs) are known to form only columnar or lamellar assemblies. There is no known example of a PBI self-assembling into a supramolecular sphere. Therefore, periodic and quasiperiodic arrays generated from spherical assemblies produced from PBIs are also not known. Here, a PBI functionalized at its imide groups with a second generation self-assembling dendron is reported to self-assemble into supramolecular spheres. These spheres self-organize in a body-centered cubic (BCC) periodic array, rarely encountered for self-assembling dendrons but often encountered in block copolymers...
October 19, 2016: Journal of the American Chemical Society
D Han, M Joksch, M Klahn, A Spannenberg, H-J Drexler, W Baumann, H Jiao, R Knitsch, M R Hansen, H Eckert, T Beweries
The synthesis of 3,5-disubstituted cyclometalated iridium(iii) hydrido complexes of the type [3,5-R2(POCOP)IrHX] (3,5-R2(POCOP) = κ(3)-C5HR2-2,6-(OPtBu2)2 with R = t-Bu, COOMe; X = Cl, H) is described. All complexes were investigated in the catalytic dehydrogenation of hydrazine borane and compared with the unsubstituted compounds [(POCOP)IrHX] (X = Cl, H). All catalysts are highly active and recyclable, clearly maintaining hydrogen production activity. The dehydrogenation products were structurally characterised by solid state NMR and FTIR spectroscopy...
October 19, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Gregory J O Beran, Joshua D Hartman, Yonaton N Heit
Molecular crystals occur widely in pharmaceuticals, foods, explosives, organic semiconductors, and many other applications. Thanks to substantial progress in electronic structure modeling of molecular crystals, attention is now shifting from basic crystal structure prediction and lattice energy modeling toward the accurate prediction of experimentally observable properties at finite temperatures and pressures. This Account discusses how fragment-based electronic structure methods can be used to model a variety of experimentally relevant molecular crystal properties...
October 18, 2016: Accounts of Chemical Research
Ewa Kober, Zofia Janas, Julia Jezierska
A series of oxidovanadium(V) complexes [VO(L-κ(4)O,N,N,O)(OR)] (1a, R = Et, L = L(1); 1b, R = Me, L = L(1); 2, R = Me, L = L(2); 3, R = Me, L = L(3)) were synthesized by the σ-bond metathesis reaction between [VO(OR)3] and the linear diaminebis(phenol) derivatives H2L (salans) containing different para-substituents on the phenoxo group [CMe3CH2CMe2, L(1); Me, L(2); Cl, L(3)]. As shown by X-ray crystallography complexes 1a, 1b, and 2 exhibit cis-α geometry, do have a stereogenic vanadium center, and exist as a racemic mixture of the Δ cis-α and Λ cis-α enantiomers...
October 18, 2016: Inorganic Chemistry
S Jamali, S Abedanzadeh, N K Khaledi, H Samouei, Z Hendi, S Zacchini, R Kia, H R Shahsavari
A mixture of the platinum(0) complex [Pt(P(t)Bu3)2] and tetrakis(acetonitrile)copper(i) hexafluorophosphate in acetone activated a water molecule and gave the hydride platinum(ii) complex [PtH(CH3CN)(P(t)Bu3)2]PF6, 1, and the hydroxide Cu(i) species. The crystal structure of complex 1 was determined by X-ray crystallography, indicating a distorted square planar geometry around the platinum center. Although three possible mechanisms are proposed for this transformation, monitoring of the reaction using NMR spectroscopy at low temperature reveals that a cooperative pathway involving formation of a Pt(0)-Cu(I) dative bond complex is the most probable pathway...
October 17, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
V S Manu, Gianluigi Veglia
Identity operation in the form of π pulses is widely used in NMR spectroscopy. For an isolated single spin system, a sequence of even number of π pulses performs an identity operation, leaving the spin state essentially unaltered. For multi-spin systems, trains of π pulses with appropriate phases and time delays modulate the spin Hamiltonian to perform operations such as decoupling and recoupling. However, experimental imperfections often jeopardize the outcome, leading to severe losses in sensitivity. Here, we demonstrate that a newly designed Genetic Algorithm (GA) is able to optimize a train of π pulses, resulting in a robust identity operation...
September 27, 2016: Journal of Magnetic Resonance
Christian Hernández, Anne-Marie Farnet Da Silva, Fabio Ziarelli, Isabelle Perraud-Gaime, Beatriz Gutiérrez-Rivera, José Antonio García-Pérez, Enrique Alarcón
The use of synthetic dyes for laccase induction in vivo has been scarcely explored. We characterized the effect of adding different synthetic dyes to liquid cultures of Pycnoporus sanguineus on laccase production. We found that carminic acid (CA) can induce 722 % and alizarin yellow 317 % more laccase than control does, and they promoted better fungal biomass development in liquid cultures. Aniline blue and crystal violet did not show such positive effect. CA and alizarin yellow were degraded up to 95 % during P...
October 14, 2016: Applied Microbiology and Biotechnology
Samuel Bernard, Mirna Chaker Bechelany, Abhijeet Lale, Vanessa Proust, Philippe Miele, Sylvie Malo, Christel Gervais
Monolith-type titanium nitride/silicon nitride nanocomposites labelled TiN/Si3N4 were prepared by reaction of polysilazanes with titanium amide, warm-pressing of the resulting polytitanosilazanes and subsequent pyrolysis of the green bodies at 1400 °C. At first, a series of polytitanosilazanes was synthesized and the role of the chemistry behind their synthesis has been studied in details by solid-state NMR, elemental analyses and molecular weight measurements. The intimate relationship between the chemistry and the processability of the single-source precursors was discussed...
October 14, 2016: Chemistry: a European Journal
Eugene Stephane Mananga, Bingwen Hu
The importance of the average Hamiltonian theory and its antecedent the Magnus expansion are discussed. The investigation of its convergence in different situations is very important. In this paper, we introduced a well-established approach to minimize the zeroth order average Hamiltonian for modified composite pulse sequence in quadrupolar spectroscopy of spin-1. We designed two modified composite pulse sequences constructed by modifying the timing sequence in the original composite pulse sequences17. We tested various configurations of times associated with the free evolution of spin system in the modified composite pulses...
October 14, 2016: Journal of Physical Chemistry. A
Maria B Mesch, Kilian Bärwinkel, Yaşar Krysiak, Charlotte Martineau, Francis Taulelle, Reinhard B Neder, Ute Kolb, Jürgen Senker
Poly(triazine imide) with incorporated lithium chloride has recently attracted substantial attention due to its photocatalytic activity for water splitting. However, an apparent H/Li disorder prevents the delineation of structure-property relationships, for example, with respect to band-gap tuning. Herein, we show that through a combination of one- and two-dimensional, multinuclear solid-state NMR spectroscopy, chemical modelling, automated electron diffraction tomography, and an analysis based on X-ray pair distribution functions, it is finally possible to resolve the H/Li substructure...
October 13, 2016: Chemistry: a European Journal
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"