scholarly journals Spatially encoded diffusion-ordered NMR spectroscopy of reaction mixtures in organic solvents

The Analyst ◽  
2018 ◽  
Vol 143 (14) ◽  
pp. 3458-3464 ◽  
Author(s):  
Ghanem Hamdoun ◽  
Ludmilla Guduff ◽  
Carine van Heijenoort ◽  
Christophe Bour ◽  
Vincent Gandon ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Organic Solvents ◽  
Spatial Encoding ◽  
Nmr Data ◽  
Dosy Nmr

Using a spatial encoding of the diffusion dimension, DOSY NMR data are acquired in less than one second for reaction mixtures in organic solvents.

Unexpected Keto-enol Tautomerism in the Cyclopyridinophane Class Direct and indirect proofs

2008 ◽  
Vol 59 (10) ◽  
Author(s):  
Paul Ionut Dron ◽  
Neculai Doru Miron ◽  
Gheorghe Surpateanu
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
Stable Conformer ◽  
Ph Measurements ◽  
Theoretical Methods ◽  
Nmr Data ◽  
Tautomeric Forms ◽  
New Compounds

The paper presents the synthesis of cyclo (bis-paraquat p-phenylene p-phenylene-carbonyl) tetrakis (hexafluorophosphate), named �CETOBOX�, and the closely related structural determinations. This compound exists in three tautomeric forms. These forms were evidentiated by NMR-data (1H-NMR, TOCSY, COSY, NOESY), UV-Vis spectra coupled with pH measurements and by synthesis. As the �CETOBOX� gives �in situ� only the corresponding monoylide, the synthesis of a new fluorescent indolizine cyclophane has been performed by a 3+2 cycloaddition. All structures of the new compounds presented herein have been established by NMR spectroscopy. Also, theoretical methods (MM3, AM1, AM1-COSMO and B88LYPDFT) have been used to determine the most stable conformer structures.

Investigation by NMR spectroscopy of the structural characteristics of modified oligo-nucleotides with pendant porphyrins

2019 ◽  
Vol 23 (07n08) ◽  
pp. 797-812 ◽  
Author(s):  
Sonja Merkaš ◽  
Mladen Žinić ◽  
Régis Rein ◽  
Nathalie Solladié
Keyword(s):  
Nmr Spectroscopy ◽  
Structural Characteristics ◽  
Strong Interactions ◽  
Light Harvesting Complexes ◽  
The Past ◽  
Naturally Occurring ◽  
Nmr Data ◽  
Intermolecular Distances ◽  
Uracil Base ◽  
Biopolymer Scaffolds

During the past years, we focused on exerting control over the position and distance of porphyrins along our specifically designed oligonucleotidic scaffold. Indeed, in naturally occurring light-harvesting complexes, biopolymer scaffolds hold pigments at intermolecular distances that optimize photon capture, electronic coupling, and energy transfer. To this end, four uridine-porphyrin conjugates (a monomer, a dimer, a tetramer and an octamer) were subjected to a comprehensive conformational analysis by using NMR spectroscopy. The collected NOE NMR data highlighted characteristic and strong interactions indicating that the glycosidic angle between the ribose and uracil base is anti. In order to further investigate the conformation of this family of molecules, NMR experiments were carried out at variable temperatures. At low temperature, the signals of the porphyrinic protons decoalesce, showing two sets of [Formula: see text]-pyrrolic protons. Similar observations are made for signals corresponding to sugar moieties and especially the H1′ protons, indicating molecular motions within our porphyrin-uridin arrays. These results testify in favor of the existence of a dynamic process between C3′-endo and C2′-endo conformations.

Integrating31P DOSY NMR Spectroscopy and Molecular Mechanics as a Powerful Tool for Unraveling the Chemical Structures of Polyoxomolybdate-Based Amphiphilic Nanohybrids in Aqueous Solution

2014 ◽  
Vol 20 (18) ◽  
pp. 5258-5270 ◽  
Author(s):  
Pavletta Shestakova ◽  
Gregory Absillis ◽  
Francisco J. Martin-Martinez ◽  
Frank De Proft ◽  
Rudolph Willem ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Nmr Spectroscopy ◽  
Molecular Mechanics ◽  
Chemical Structures ◽  
Dosy Nmr

Molecular Weights of Cyclic and Hollow Clusters Measured by DOSY NMR Spectroscopy

2009 ◽  
Vol 131 (47) ◽  
pp. 17254-17259 ◽  
Author(s):  
Sébastien Floquet ◽  
Sébastien Brun ◽  
Jean-François Lemonnier ◽  
Marc Henry ◽  
Marc-André Delsuc ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Molecular Weights ◽  
Dosy Nmr

Hexaethyl-2,4-dicarba-nido-hexaborane(8), Deprotonation and Complexation Studied by NMR Spectroscopy and Density Functional Theory (DFT) Calculations

2004 ◽  
Vol 59 (6) ◽  
pp. 685-691 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Hans-Jörg Schanz
Keyword(s):  
Density Functional Theory ◽  
Nmr Spectroscopy ◽  
Density Functional ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Analogous Reaction ◽  
Sandwich Complex ◽  
Dft Methods ◽  
Functional Theory ◽  
Nmr Data

Deprotonation of hexaethyl-2,4-dicarba-nido-borane(8) 2 leads first to the hexaethyl-2,4-dicarbanido- borate(1−) 3, and further deprotonation, using BuLi/KOtBu, gives the hexaethyl-2,4-dicarbanido- hexaborate(2−) 4. The reaction of 3 with FeCl2 affords the commo-ferracarborane [Fe(Et6-2,4- C2B4H)2] 5, and the analogous reaction of 4 leads to the anionic sandwich complex [Fe(Et6-2,4- C2B4)2]2− 6 which can be protonated to give 5. The complex 5 contains two hydrido ligands, each bridging the iron and two boron atoms. Reactions were monitored and the products were characterised by 11B NMR spectroscopy in solution. The geometries of the carboranes, the borates (all unsubstituted and permethyl-substituted) and the iron complexes (all unsubstituted) were optimised by DFT methods [B3LYP/6-311+G(d,p) or B3LYP/6-31+G(d)], and the relevant NMR data [chemical shifts δ11B, δ13C, δ57Fe, and coupling constants 1J(13C,1H), 1J(11B,1H), 1J(57Fe,1H), 1J(57Fe,11B)] were calculated at the same level of theory.

scholarly journals Stability Evaluation and Degradation Studies of DAC® Hyaluronic-Polylactide Based Hydrogel by DOSY NMR Spectroscopy

Biomolecules ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1478
Author(s):  
Tatiana Guzzo ◽  
Fabio Barile ◽  
Cecilia Marras ◽  
Davide Bellini ◽  
Walter Mandaliti ◽  
...  
Keyword(s):  
Hyaluronic Acid ◽  
Nmr Spectroscopy ◽  
Bone Growth ◽  
Orthopedic Implants ◽  
Structured Surfaces ◽  
Physiological Conditions ◽  
Hydrophilic Character ◽  
Dosy Nmr ◽  
The Stability

The stability and the degradation of polymers in physiological conditions are very important issues in biomedical applications. The copolymer of hyaluronic acid and poly-D,L-lactic acid (made available in a product called DAC®) produces a hydrogel which retains the hydrophobic character of the poly-D,L-lactide sidechains and the hydrophilic character of a hyaluronic acid backbone. This hydrogel is a suitable device for the coating of orthopedic implants with structured surfaces. In fact, this gel creates a temporary barrier to bacterial adhesion by inhibiting colonization, thus preventing the formation of the biofilm and the onset of an infection. Reabsorbed in about 72 h after the implant, this hydrogel does not hinder bone growth processes. In the need to assess stability and degradation of both the hyaluronan backbone and of the polylactic chains along time and temperature, we identified NMR spectroscopy as a privileged technique for the characterization of the released species, and we applied diffusion-ordered NMR spectroscopy (DOSY-NMR) for the investigation of molecular weight dispersion. Our diffusion studies of DAC® in physiological conditions provided a full understanding of the product degradation by overcoming the limitations observed in applying classical chromatography approaches by gel permeation UV.

Symmetric spatial encoding in ultrafast 2D NMR spectroscopy

2006 ◽  
Vol 178 (1) ◽  
pp. 33-41 ◽  
Author(s):  
Boaz Shapira ◽  
Yoav Shrot ◽  
Lucio Frydman
Keyword(s):  
Nmr Spectroscopy ◽  
2D Nmr ◽  
2D Nmr Spectroscopy ◽  
Spatial Encoding ◽  
Ultrafast 2D Nmr

Oligophosphin-Liganden, III [1] Bis(3-diphenylphosphinopropyl)phenylphospbinchloroiridium(I) * * und dessen Carbonyl-und Hydridderivate / Oligophosphine Ligands, III [1] Bis(3-diphenylphosphinopropyl)phenylphosphinechloroiridium(I) and its Carbonyl and Hydride Derivatives

1981 ◽  
Vol 36 (6) ◽  
pp. 672-676 ◽  
Author(s):  
Ertugrul Arpac ◽  
Lutz Dahlenburg
Keyword(s):  
Nmr Spectroscopy ◽  
Title Complex ◽  
Trigonal Bipyramidal Geometry ◽  
Trigonal Bipyramidal ◽  
Nmr Data ◽  
Ir And Nmr Spectroscopy ◽  
Infrared Intensities

AbstractThe title complex, IrCl(bdpp) (1), where bdpp = PhP[(CH2)3PPh2]2, has been obtained from [IrCl(C8H14)2]2 and the triphosphine ligand. Characteristic 31P NMR data of 1 dissolved in THF are δ(P̲Ph2) = 2.7 and δ(P̲Ph) = - 19.9 with cis-2J(P̲IrP̲) = 32.8 Hz. Reaction of 1 with CO proceeds stepwise to yield five-coordinate IrCl(CO)(bdpp) (2) and ionic [Ir(CO)2(bdpp)]Cl (3). A trigonal bipyramidal geometry with equatorial CO ligands is assigned to the cation of 3 on the basis of its v(CO) infrared intensities. When allowed to react with HCl, 1 gives the monohydride IrHCl2(bdpp) (4). Similarly, the dihydride IrH2Cl(bdpp) (5) is formed from 1 and H2. As has been established by IR and NMR spectroscopy, 4 and 5 adopt cis-mer-octahedral structures.

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