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Solid state NMR

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https://www.readbyqxmd.com/read/29045027/step-up-synthesis-of-periodic-mesoporous-organosilicas-with-the-framework-of-tyrosine-tyr-pmos-and-performance-on-horseradish-peroxidase-immobilization
#1
Jianqiang Wang, Wenqi Zhang, Changqing Gu, Wenpei Zhang, Man Zhou, Zhiwei Wang, Cheng Guo, Linbing Sun
A new amino-acid bridged periodic mesoporous organosilicas (PMOs) have been constructed via hydrolysis and condensation reactions under acid condition in the presence of template. The tyrosine bissilylated organic precursor (TBOS) was first prepared through multi-step reaction using tyrosine (natural amino acid) as starting material. The PMOs with the framework of tyrosine (Tyr-PMOs) were architected by simultaneously using TBOS and TEOS as complex silicon source in the condensation process. All the Tyr-PMOs materials were characterized by XRD, FT-IR, N2 adsorption-desorption, TEM, SEM and 29Si solid-state NMR to confirm the structure...
October 18, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/29044965/breaking-bonds-forming-nanographene-diradicals-with-pressure
#2
Juan Casado, Maude Desroches, Paula Mayorga Burrezo, Joel Boismenu-Lavoie, Miriam Peña Alvarez, Carlos Gómez Garcia, Jon Mattin Matxain, David Casanova, Jean Francois Morin
New anthanthrone-based polycyclic scaffolds possessing peripheral crowed quinodimethanes have been prepared. While the compounds adopt a closed-shell butterfly shaped structure in the ground state, a curved-to-planar fluxional dynamic inversion is accessible with a low energy barrier through a diradical transition-state. Mainly driven by the release of strain attributed to the steric hindrance at the peri position of the anthanthrone core, a low-lying diradical state is accessible through planarization of the core...
October 18, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29044943/fast-lithium-ion-transportation-in-crystalline-polymer-electrolytes
#3
Xiao-Bin Fu, Guang Yang, Jin-Ze Wu, Jianchen Wang, Qun Chen, Yefeng Yao
Fast lithium-ion transportation is found in the crystalline polymer electrolytes, α-CD-PEOn/Li+ (n = 12, 40), prepared by self-assembly of α-cyclodextrin (CD), polyethylene oxide (PEO) and Li+ salts. A detailed solid-state NMR study combined with X-ray diffraction technique reveals the unique structural features of the samples, that is, a) the tunnel structure formed by the assembled CDs, providing the ordered long-range pathway for Li+ ion transportation; b) the all-trans conformational sequence of the PEO chains in the tunnels, attenuating significantly the coordination between Li+ and the EO segments...
October 16, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29044939/synthesis-and-characterization-of-high-quantum-yield-and-oscillator-strength-6-chloro-2-4-cynophenyl-4-phenyl-quinoline-cl-cn-dpq-organic-phosphor-for-solid-state-lighting
#4
Minakshi Ghate, H K Dahule, N Thejo Kalyani, S J Dhoble
A novel blue luminescent 6-chloro-2-(4-cynophenyl) substituted diphenyl quinoline (Cl-CN DPQ) organic phosphor has been synthesized by the acid-catalyzed Friedlander reaction and then characterized to confirm structural, optical and thermal properties. Structural properties of Cl-CN-DPQ were analyzed by Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR) spectroscopy, X-ray diffraction technique (XRD) and scanning electron microscopy (SEM) and energy dispersive analysis of X-ray (EDAX) spectroscopy...
October 18, 2017: Luminescence: the Journal of Biological and Chemical Luminescence
https://www.readbyqxmd.com/read/29044220/structure-of-melanins-from-the-fungi-ochroconis-lascauxensis-and-ochroconis-anomala-contaminating-rock-art-in-the-lascaux-cave
#5
José Maria De la Rosa, Pedro M Martin-Sanchez, Santiago Sanchez-Cortes, Bernardo Hermosin, Heike Knicker, Cesareo Saiz-Jimenez
Two novel species of the fungal genus Ochroconis, O. lascauxensis and O. anomala have been isolated from the walls of the Lascaux Cave, France. The interest in these fungi and their melanins lies in the formation of black stains on the walls and rock art which threatens the integrity of the paintings. Here we report solid-state cross polarization magic-angle spinning (13)C and (15)N nuclear magnetic resonance (NMR) spectroscopy and surface-enhanced Raman spectroscopy (SERS) of the melanins extracted from the mycelia of O...
October 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29042336/physicochemical-properties-of-inclusion-complexes-of-highly-soluble-%C3%AE-cyclodextrins-with-highly-hydrophobic-testosterone-propionate
#6
Christian Celia, Angela Scala, Rosanna Stancanelli, Emanuela Surdo, Donatella Paolino, Alessandro Grattoni, Nicola Micale, Vincenza Crupi, Domenico Majolino, Massimo Fresta, Silvana Tommasini, Valentina Venuti, Cinzia Anna Ventura
Hydroxypropyl-β-cyclodextrin (HP-β-CyD) and sulfobutyl ether-β-cyclodextrin (SBE-β-CyD) were used to generate hydrophilic complexes of the poorly water-soluble drug testosterone propionate (TP). The inclusion complexes were obtained by freeze-drying, and then analyzed at both liquid and solid states. Phase solubility studies, performed according to the type-AL solubility diagrams of TP in presence of both CyDs, suggested the formation of water-soluble complexes at 1:1 molar ratio. These results were confirmed by continuous variation method (Job's plot)...
October 14, 2017: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/29037036/intramolecular-london-dispersion-interaction-effects-on-gas-phase-and-solid-state-structures-of-diamondoid-dimers
#7
Andrey A Fokin, Tatyana S Zhuk, Sebastian Blomeyer, Cristóbal Pérez, Lesya V Chernish, Alexander Pashenko, Jens Antony, Yury V Vishnevskiy, Raphael Jf Berger, Stefan Grimme, Christian Logemann, Melanie Schnell, Norbert W Mitzel, Peter R Schreiner
The covalent diamantyl (C28H38) and oxadiamantyl (C26H34O2) dimers are stabilized by London dispersion attractions between the dimer moieties. Their solid state and gas phase structures were studied using a multi-technique approach including single-crystal X-ray diffraction (XRD), gas-phase electron diffraction (GED), a combined GED/microwave (MW) spectroscopy study, and quantum-chemical calculations. The inclusion of medium-range electron correlation as well as the London dispersion energy in density functional theory is essential to reproduce the experimental geometries...
October 17, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29035839/insights-into-protein-misfolding-and-aggregation-enabled-by-solid-state-nmr-spectroscopy
#8
REVIEW
Patrick C A van der Wel
The aggregation of proteins and peptides into a variety of insoluble, and often non-native, aggregated states plays a central role in many devastating diseases. Analogous processes undermine the efficacy of polypeptide-based biological pharmaceuticals, but are also being leveraged in the design of biologically inspired self-assembling materials. This Trends article surveys the essential contributions made by recent solid-state NMR (ssNMR) studies to our understanding of the structural features of polypeptide aggregates, and how such findings are informing our thinking about the molecular mechanisms of misfolding and aggregation...
October 4, 2017: Solid State Nuclear Magnetic Resonance
https://www.readbyqxmd.com/read/29035811/moving-towards-fast-characterization-of-polymorphic-drugs-by-solid-state-nmr-spectroscopy
#9
Rosalynn Quiñones, Robbie J Iuliucci, Grayce Behnke, Ryanne Brown, Deben Shoup, Taylor M Riedel, Christine Plavchak, Brooke E Lininger, Jonathan M Spehar
Solid-state nuclear magnetic resonance (SS-NMR) spectroscopy has become a common technique to study polymorphism in pharmaceutical solids at high-resolution. However, high-throughput application of high resolution SS-NMR spectroscopy is severely limited by the long (1)H spin-lattice relaxation (T1) that is common to solid phase compounds. Here, we demonstrate the use of paramagnetic relaxation reagents such as chromium (III) acetylacetonate (Cr(acac)3) and nickel (II) acetylacetonate (Ni(acac)2) for fast data acquisition by significantly reducing the T1 value for carbamazepine Forms I, II, III, and dihydrate, cimetidine Forms A and B, nabumetone Form I, and acetaminophen Form I polymorphs...
October 3, 2017: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/29035276/unctuous-zro2-nanoparticles-with-improved-functional-attributes-as-lubricant-additives
#10
Jorge Espina-Casado, Alfonso Fernández-González, Ángel José Del Reguero-Huerga, Humberto Rodríguez-Solla, Marta Elena Díaz-García, Rosana Badía Laíño
One of the main drawbacks in the application of metal oxide nanoparticles as lubricant additives is their poor stability in organic media, despite the good anti-wear, friction-reducing and high load capacity properties described for these materials. In this work, we present a novel procedure to chemically cap the surface of ZrO2 nanoparticles (ZrO2NPs) with long hydrocarbon chains in order to obtain stable dispersions of ZrO2NPs in non-aqueous media without disrupting their attributes as lubricant additives...
October 16, 2017: Nanotechnology
https://www.readbyqxmd.com/read/29031975/new-polymorph-form-of-dexamethasone-acetate
#11
Ronaldo Pedro da Silva, Mateus Felipe Schuchter Ambrósio, Luciana Almeida Piovesan, Maria Clara Ramalho Freitas, Daniel Lima Marques de Aguiar, Bruno Araújo Cautiero Horta, Eugenio Epprecht, Rosane Aguiar da Silva San Gil, Lorenzo do Canto Visentin
A new monohydrated polymorph of dexamethasone acetate (DEX-II) was crystallized and its crystal structure characterized. The different analytical techniques used for describing its structural and vibrational properties were: single crystal (SCXRD) and polycrystal (PXRD) X-ray diffraction, solid state nuclear magnetic resonance (solid-state NMR), infrared spectroscopy (IR). A Hirshfeld surface (HS) analysis was carried out through self-arrangement cemented by H-bonds observed in this new polymorph. This new polymorph form appeared because of self-arrangement via classical hydrogen bonds around the water molecule...
October 11, 2017: Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/29031269/visualising-crystal-packing-interactions-in-solid-state-nmr-concepts-and-applications
#12
Miri Zilka, Simone Sturniolo, Steven P Brown, Jonathan R Yates
In this article, we introduce and apply a methodology, based on density functional theory and the gauge-including projector augmented wave approach, to explore the effects of packing interactions on solid-state nuclear magnetic resonance (NMR) parameters. A visual map derived from a so-termed "magnetic shielding contribution field" can be made of the contributions to the magnetic shielding of a specific site-partitioning the chemical shift to specific interactions. The relation to the established approaches of examining the molecule to crystal change in the chemical shift and the nuclear independent chemical shift is established...
October 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29030606/molecular-mechanism-of-synergy-between-the-antimicrobial-peptides-pgla-and-magainin-2
#13
Jonathan Zerweck, Erik Strandberg, Olga Kukharenko, Johannes Reichert, Jochen Bürck, Parvesh Wadhwani, Anne S Ulrich
PGLa and magainin 2 (MAG2) are amphiphilic α-helical membranolytic peptides from frog skin with known synergistic antimicrobial activity. By systematically mutating residues in the two peptides it was possible to identify the ones crucial for the synergy, as monitored by biological assays, fluorescence vesicle leakage, and solid-state (15)N-NMR. Electrostatic interactions between anionic groups in MAG2 and cationic residues in PGLa enhance synergy but are not necessary for the synergistic effect. Instead, two Gly residues (7 and 11) in a so-called GxxxG motif in PGLa are necessary for synergy...
October 13, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29030245/effect-of-phosphatidylcholine-bilayer-thickness-and-molecular-order-on-the-binding-of-the-antimicrobial-peptide-maculatin-1-1
#14
Tzong-Hsien Lee, Marc-Antoine Sani, Sarah Overall, Frances Separovic, Marie-Isabel Aguilar
Antimicrobial peptides (AMPs) interact directly with bacterial membrane lipids. Thus, changes in the lipid composition of bacterial membranes can have profound effects on the activity of AMPs. In order to understand the effect of bilayer thickness and molecular order on the activity of AMPs, the interaction of maculatin 1.1 (Mac1.1) with phosphatidylcholine (PC) model membranes composed of different monounsaturated acyl chain lengths between 14 and 22 carbons was characterised by dual polarisation interferometry (DPI) and 31P and 1H solid-state NMR techniques...
October 10, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/29027800/chromophore-distortions-in-photointermediates-of-proteorhodopsin-visualized-by-dnp-enhanced-solid-state-nmr
#15
Michaela Mehler, Carl Elias Eckert, Alexander J Leeder, Jagdeep Kaur, Tobias Fischer, Nina Kubatova, Lynda J Brown, Richard C D Brown, Johanna Becker-Baldus, Josef Wachtveitl, Clemens Glaubitz
Proteorhodopsin (PR) is the most abundant retinal protein on earth and functions as a light-driven proton pump. Despite of extensive efforts, structural data for PR photointermediate states have not been obtained. Based on DNP-enhanced solid-state NMR, we were able to analyze the retinal polyene chain between positions C10 and C15 as well as the Schiff base nitrogen in the ground state in comparison to light induced, cryo-trapped K- and M-states. A high M-state population could be achieved by preventing reprotonation of the Schiff base through a mutation of the primary proton donor (E108Q)...
October 13, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29024352/characterization-of-conjugation-pattern-in-large-polysaccharide-protein-conjugates-by-nmr
#16
Stefano Giuntini, Evita Balducci, Linda Cerofolini, Enrico Ravera, Marco Fragai, Francesco Berti, Claudio Luchinat
Carbohydrate-based vaccines are among the safest and most effective vaccines and represent potent tools for prevention of life-threatening bacterial infectious diseases, like meningitis and pneumonia. The chemical conjugation of a weak antigen to protein as a source of T-cell epitopes generates a glycoconjugate vaccine, that results more immunogenic. Several methods have been used so far to characterize the resulting polysaccharide-protein conjugates. However, a reduced number of methodologies has been proposed for measuring the degree of saccharide conjugation at the possible protein sites...
October 10, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29022618/enhancing-the-resolution-of-1-h-and-13-c-solid-state-nmr-spectra-by-reduction-of-anisotropic-bulk-magnetic-susceptibility-broadening
#17
Michael P Hanrahan, Amrit Venkatesh, Scott L Carnahan, Julie L Calahan, Joseph W Lubach, Eric J Munson, Aaron J Rossini
We demonstrate that natural isotopic abundance 2D heteronuclear correlation (HETCOR) solid-state NMR spectra can be used to significantly reduce or eliminate the broadening of (1)H and (13)C solid-state NMR spectra of organic solids due to anisotropic bulk magnetic susceptibility (ABMS). ABMS often manifests in solids with aromatic groups, such as active pharmaceutical ingredients (APIs), and inhomogeneously broadens the NMR peaks of all nuclei in the sample. Inhomogeneous peaks with full widths at half maximum (FWHM) of ∼1 ppm typically result from ABMS broadening and the low spectral resolution impedes the analysis of solid-state NMR spectra...
October 12, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29016110/bacterial-cellulose-ionogels-as-chemosensory-supports
#18
Chip J Smith, Durgesh Vinod Wagle, Hugh M O'Neill, Barbara R Evans, Sheila N Baker, Gary A Baker
To fully leverage the advantages of ionic liquids for many applications, it is necessary to immobilize or encapsulate the fluids within an inert, robust, quasi-solid-state format that does not disrupt their many desirable, inherent features. The formation of ionogels represents a promising approach, however, many earlier approaches suffer from solvent/matrix incompatibility, optical opacity, embrittlement, matrix-limited thermal stability, and/or inadequate ionic liquid loading. We offer a solution to these limitations by demonstrating a straightforward and effective strategy toward flexible and durable ionogels comprising bacterial cellulose supports hosting as much as 99% ionic liquid by total weight...
October 10, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28994783/atomic-scale-structural-studies-of-macromolecular-assemblies-by-solid-state-nuclear-magnetic-resonance-spectroscopy
#19
Antoine Loquet, James Tolchard, Melanie Berbon, Denis Martinez, Birgit Habenstein
Supramolecular protein assemblies play fundamental roles in biological processes ranging from host-pathogen interaction, viral infection to the propagation of neurodegenerative disorders. Such assemblies consist in multiple protein subunits organized in a non-covalent way to form large macromolecular objects that can execute a variety of cellular functions or cause detrimental consequences. Atomic insights into the assembly mechanisms and the functioning of those macromolecular assemblies remain often scarce since their inherent insolubility and non-crystallinity often drastically reduces the quality of the data obtained from most techniques used in structural biology, such as X-ray crystallography and solution Nuclear Magnetic Resonance (NMR)...
September 17, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28994190/analysis-of-molecular-orientation-in-organic-semiconducting-thin-films-using-static-dynamic-nuclear-polarization-enhanced-solid-state-nmr
#20
Katsuaki Suzuki, Shosei Kubo, Fabien Aussenac, Frank Engelke, Tatsuya Fukushima, Hironori Kaji
Molecular orientation in amorphous organic semiconducting thin film devices is an important issue affecting device performances. However, to date it has not been possible to analyze the "distribution" of the orientations. Although solid-state NMR (ssNMR) can provide information on the distribution of molecular orientations, the technique is limited because of the small amounts of sample in the devices and the low sensitivity of ssNMR. Here, we report the first application of dynamic nuclear polarization enhanced ssNMR (DNP-ssNMR) to orientational analysis of amorphous phenyldi(pyren-1-yl)phosphine oxide (POPy2)...
October 9, 2017: Angewandte Chemie
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