Read by QxMD icon Read


Ludmilla Guduff, Ilya Kuprov, Carine van Heijenoort, Jean-Nicolas Dumez
We show that the acquisition of 3D diffusion-ordered NMR spectroscopy (DOSY) experiments can be accelerated significantly with the use of spatial encoding (SPEN). The SPEN DOSY approach is discussed, analysed with numerical simulation, and illustrated on a mixture of small molecules.
December 5, 2016: Chemical Communications: Chem Comm
Eliška Procházková, Andreas Kolmer, Julian Ilgen, Mira Schwab, Lukas Kaltschnee, Maic Fredersdorf, Volker Schmidts, Raffael C Wende, Peter R Schreiner, Christina M Thiele
We report on a detailed NMR spectroscopic study of the catalyst-substrate interaction of a highly enantioselective oligopeptide catalyst that is used for the kinetic resolution of trans-cycloalkane-1,2-diols via monoacylation. The extraordinary selectivity has been rationalized by molecular dynamics as well as density functional theory (DFT) computations. Herein we describe the conformational analysis of the organocatalyst studied by a combination of nuclear Overhauser effect (NOE) and residual dipolar coupling (RDC)-based methods that resulted in an ensemble of four final conformers...
November 23, 2016: Angewandte Chemie
Mohammadali Foroozandeh, Laura Castañar, Lucas G Martins, Davy Sinnaeve, Guilherme Dal Poggetto, Claudio F Tormena, Ralph W Adams, Gareth A Morris, Mathias Nilsson
Diffusion-ordered spectroscopy (DOSY) is an effective method for the analysis of intact mixtures, but the quality of results is critically limited by resolution in the NMR dimension. A new experiment integrating diffusion weighting into the PSYCHE method for pure shift NMR spectroscopy allows DOSY spectra to be measured with ultrahigh NMR resolution at improved sensitivity.
November 10, 2016: Angewandte Chemie
Kayla M Diemoz, Sean O Wilson, Annaliese K Franz
A series of new 1,3-disiloxanediols has been synthesized, including naphthyl-substituted and unsymmetrical siloxanes, and demonstrated as a new class of anion-binding catalysts. In the absence of anions, diffusion-ordered spectroscopy (DOSY) displays self-association of 1,3-disiloxanediols through hydrogen-bonding interactions. Binding constants determined for 1,3-disiloxanediol catalysts indicate strong hydrogen-bonding and anion-binding abilities with unsymmetrical siloxanes displaying different hydrogen-bonding abilities for each silanol group...
November 10, 2016: Chemistry: a European Journal
Roan A S Vasdev, Dan Preston, Synøve Ø Scottwell, Heather J L Brooks, James D Crowley, Michael P Schramm
A small family of [Co₂(Lpytrz)₃](6+) cylinders was synthesised from bis(bidentate) 2-pyridyl-1,2,3-triazole "click" ligands (Lpytrz) through an "assembly-followed-by-oxidation" method. The cylinders were characterised using ¹H, (13)C, and DOSY NMR, IR, and UV-Vis spectroscopies, along with electrospray ionisation mass spectrometry (ESMS). Stability studies were conducted in dimethyl sulfoxide (DMSO) and D₂O. In contrast to similar, previously studied, [Fe₂(Lpytrz)₃](4+) helicates the more kinetically inert [Co₂(Lpytrz)₃](6+) systems proved stable (over a period of days) when exposed to DMSO and were even more stable in D₂O...
November 16, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Tonimar D A Senra, Abdel Khoukh, Jacques Desbrières
Surfactant-polysaccharide complexes (SPEC) based on oppositely charged sodium 1-decanesulfonate and quaternized chitosan were studied using two techniques. The first one, the conductivity, is a very often used even when diffusion NMR (DOSY) technique was considered for the first time for such systems involving surfactant and chitosan derivatives and more generally polysaccharides. The physico-chemical characteristics of pure surfactant solutions as well as SPECs were determined and compared according to the considered experimental technique...
January 20, 2017: Carbohydrate Polymers
Sandrine Denis-Quanquin, François Riobé, Marc-André Delsuc, Olivier Maury, Nicolas Giraud
Diffusion ordered NMR is implemented to determine accurately the mobility of paramagnetic tris-dipicolinate lanthanide complexes that are versatile probes of protein structure. It is shown that diffusion coefficient ratios can be measured with an accuracy of 1 % using a standard BPPLED pulse sequence, which allows for observing significant, though weak, variations when different species are interacting with the paramagnetic compound. We demonstrate that this approach is complementary to classical chemical shift titration experiments, and that it can be applied successfully to probe the supramolecular dynamic interactions between lanthanide complexes and small molecules on the one hand, or to determine rapidly their affinity for a targeted protein...
November 2, 2016: Chemistry: a European Journal
Manon Ripoll, Patrick Neuberg, Antoine Kichler, Nassera Tounsi, Alain Wagner, Jean-Serge Remy
A novel generation of pH-responsive Photopolymerized Diacetylenic Amphiphile (PDA) micelles with a diameter of 10 nm was designed and optimized for the intracellular delivery of siRNAs. Dialysis and photo-polymerization of the micelles allowed a strong reduction of the cytotoxicity of the nanovector, while the hydrophilic histidine headgroup permitted enhancing the siRNA delivery potential by improving the endosomal escape via imidazole protonation. These PDA-micellar systems were fully characterized by DLS, TEM, and DOSY-NMR experiments...
November 2, 2016: ACS Applied Materials & Interfaces
Jeffrey M Ting, Swapnil Tale, Anatolii A Purchel, Seamus D Jones, Lakmini Widanapathirana, Zachary P Tolstyka, Li Guo, Steven J Guillaudeu, Frank S Bates, Theresa M Reineke
Polymeric excipients are crucial ingredients in modern pills, increasing the therapeutic bioavailability, safety, stability, and accessibility of lifesaving products to combat diseases in developed and developing countries worldwide. Because many early-pipeline drugs are clinically intractable due to hydrophobicity and crystallinity, new solubilizing excipients can reposition successful and even failed compounds to more effective and inexpensive oral formulations. With assistance from high-throughput controlled polymerization and screening tools, we employed a strategic, molecular evolution approach to systematically modulate designer excipients based on the cyclic imide chemical groups of an important (yet relatively insoluble) drug phenytoin...
October 26, 2016: ACS Central Science
Victor A Tallada, Jürg Bähler
No abstract text is available yet for this article.
October 28, 2016: Cell Cycle
Fang-Wei Liu, Li-Ya Niu, Yong Chen, Vaidhyanathan Ramamurthy, Li-Zhu Wu, Chen-Ho Tung, Yu-Zhe Chen, Qing-Zheng Yang
A platinum(II) bipyridyl complex bearing bis-ureidopyrimidinone (Pt-bisUPy) has been designed and its self-assembling behavior has been thoroughly investigated by (1) H NMR, DOSY NMR, Ubbelohde viscometry analysis, UV/Vis, and emission spectroscopies. Pt-bisUPy underwent concentration-dependent ring-chain polymerization in apolar solvents. Hydrogen-bonding interactions play an important role during the formation of the supramolecular polymers. Hydrogen-bonded supramolecular polymers were transformed to nanoparticles in water through the miniemulsion method...
October 28, 2016: Chemistry: a European Journal
William H Casey, Anne Oliveri, Christopher Colla, Cory Perkins, Noushin Akhavantabib, Joseph Callahan, Corey Pilgrim, Scott Smart, Long Pan, Paul Cheong
The solution chemistry of aluminum has long interested scientists because of its relevance to materials chemistry and geochemistry. The dynamic behavior of large aluminum-oxo-hydroxo clusters, specifically [Al13O4(OH)24(H2O)12]7+ (Al13), is the focus of this paper. 27Al-NMR, 1H-NMR, and 1H-DOSY were used to follow the isomerization of the ε-Al13 in the presence of glycine and Ca2+ at 90C. Although the conversion of ε-Al13 to new clusters and/or Baker-Figgis-Keggin isomers has been studied previously, new 1H-NMR and 1H-DOSY analyses provides information about the role of glycine, the ligated intermediates, and the mechanism of isomerization...
October 26, 2016: Chemistry: a European Journal
Kamran Balighi, Maryam Daneshpazhooh, Nessa Aghazadeh, Vahide Saeidi, Farzam Shahpouri, Pardis Hejazi, Cheyda Chams-Davatchi
HINTERGRUND UND ZIELE: Pemphigus vulgaris (PV) wird in der Regel mit systemischen Corticosteroiden und Immunsuppressiva behandelt. Avaskuläre Nekrose (AVN) des Hüftkopfes ist eine gut bekannte schwerere Komplikation einer Corticosteroid-Therapie. Die Charakteristika dieser schweren Komplikation bei PV sind nach wie vor unbekannt. PATIENTEN UND METHODEN: Nicht kontrollierte, retrospektive Untersuchung aller PV-bedingten AVN-Fälle, die in einer iranischen Klinik für bullöse Autoimmunerkrankungen zwischen 1985 und 2013 diagnostiziert wurden...
October 2016: Journal der Deutschen Dermatologischen Gesellschaft, Journal of the German Society of Dermatology: JDDG
Sebastian Bachmann, Björn Gernert, Dietmar Stalke
In this paper we present the aggregational motifs of the widely used alkali-metal cyclopentadienides (CpLi, CpNa, CpK, CpRb, CpCs) in THF-d8 solution estimated by ECC-DOSY NMR spectroscopy. They form monomeric contact ion pairs (CIPs) in THF-d8 solution, whereas in NH3 solvent-separated ion pairs (SSIPs) are observed. The applicability of ECC-DOSY is further advanced by introducing ECC-MW estimation software.
October 12, 2016: Chemical Communications: Chem Comm
Soumen K Samanta, Damien Moncelet, Volker Briken, Lyle Isaacs
Self-assembly of ligand 1 and Pd(NO3)2 delivers Fujita-type metal organic polyhedron (MOP) 3 which bears 24 covalently attached methyl viologen units on its external surface as evidenced by 1H NMR, DOSY NMR, electrospray mass spectrometry, TEM, and AFM measurements. MOP 3 undergoes non-covalent complexation with cucurbit[n]urils to yield MOPs 4 - 6 with diameter ≈ 5-6 nm. MOP 5 can be fully loaded with doxorubicin prodrug 2 via hetero ternary complex formation to yield 7. The MOPs exhibit excellent stability toward neutral to slightly acidic pH in 10 mM sodium phosphate buffer mitigating the concern of disassembly during circulation...
October 10, 2016: Journal of the American Chemical Society
Yan Qiao, Wenzhi Ge, Lingyu Jia, Xianglin Hou, Yingxiong Wang, Christian M Pedersen
Low temperature (1)H- and (19)F-DOSY have been used for analyzing reactive intermediates in glycosylation reactions, where a glycosyl trichloroacetimidate donor has been activated using different catalysts. The DOSY protocols have been optimized for low temperature experiments and provided new insight into acid catalyzed glycosylation chemistry. From the study a new glycosylation intermediate was characterized.
September 15, 2016: Chemical Communications: Chem Comm
Lotta Turunen, Ulrike Warzok, Rakesh Puttreddy, Ngong Kodiah Beyeh, Christoph A Schalley, Kari Rissanen
Two [N⋅⋅⋅I(+) ⋅⋅⋅N] halogen-bonded dimeric capsules using tetrakis(3-pyridyl)ethylene cavitands with different lower rim alkyl chains are synthesized and analyzed in solution and the gas phase. These first examples of symmetrical dimeric capsules making use of the iodonium ion (I(+) ) as the main connecting module are characterized by (1) H NMR spectroscopy, diffusion ordered NMR spectroscopy (DOSY), electrospray ionization mass spectrometry (ESI-MS), and ion mobility-mass spectrometry (TW-IMS) experiments...
October 6, 2016: Angewandte Chemie
Shogo Morisako, Rong Shang, Yohsuke Yamamoto
The new sterically hindered piperidine analog, dispiro[cyclohexane-2,2'-piperidine-6',2″-cyclohexane] (CPC(H), 2), and its N-methylated derivative CPC(Me) (3) were synthesized from commercially available starting materials in short steps. The N-lithiated amide LiCPC (4) was also isolated from 2 as a cyclictrimer in single crystals and showed slightly larger steric hindrance than that of lithium 2,2,6,6-tetramethylpiperidide (LiTMP) in the competitive methylation reaction with methyl trifluoromethanesulfonate...
October 17, 2016: Inorganic Chemistry
Guilherme Dal Poggetto, Victor U Antunes, Mathias Nilsson, Gareth A Morris, Cláudio F Tormena
NMR is the most versatile tool for the analysis of organic compounds and, in combination with DOSY ("Diffusion-Ordered Spectroscopy"), can give information on compounds in complex mixtures without the need for physical separation. In mixtures where the components' diffusion coefficients are nearly identical, for example due to similar sizes, MAD ("Matrix-Assisted DOSY") can help separate the signals of different constituents, resolving their spectra. Unfortunately, DOSY (including MAD) typically fails where signals overlap, as is common in (1) H NMR...
September 28, 2016: Magnetic Resonance in Chemistry: MRC
Giuseppe Consiglio, Ivan Pietro Oliveri, Salvatore Failla, Santo Di Bella
This contribution explores, through detailed (1)H NMR, DOSY NMR, optical absorption, and circular dichroism spectroscopic studies, the aggregation properties in solution of noncoordinating solvents of some new Zn(II) Schiff-base complexes, (R)-1, (S)-1, and (R)-2, derived from the chiral trans-1,2-diaminocyclohexane. It is found that chloroform solutions of 1 are characterized by the presence of three species, the predominance of which consists of large oligomeric aggregates. For chloroform solutions of 1, upon heating or standing, all species are irreversibly converted into a dimer, 1C, which is very stable and hardly disaggregable...
October 17, 2016: Inorganic Chemistry
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"