A systematic investigation of the reaction of SiF2 with ethylene and six methyl-substituted ethylenes. II. Characterization of polymeric products, open chain organosilicon derivatives, and 1,2-disilacyclobutanes

1980 ◽  
Vol 58 (5) ◽  
pp. 425-435 ◽  
Author(s):  
William F. Reynolds ◽  
James C. Thompson ◽  
A. P. Gerald Wright
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
Chemical Shifts ◽  
Systematic Investigation ◽  
Open Chain ◽  
Alkyl Substitution ◽  
Tail Structure

Polymers produced by the reaction of SiF2 with olefins have been characterized by 13C and 29Si nmr spectroscopy and have been found to have a regular head-to-tail structure with isolated SiF2 groups between olefin units. Only minor proportions of Si2F4 units are formed. The open chain organosilicon derivatives formed in the reaction are, with one exception, isomers of 1,2-disilacyclohexanes. The 1,2-disilacyclobutanes are formed stereospecifically with retention of alkyl stereochemistry. 19F chemical shifts can be predicted by additive chemical shift parameters for the effect of alkyl substitution.

scholarly journals Structure of Nanobody Nb23

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3567
Author(s):  
Mathias Percipalle ◽  
Yamanappa Hunashal ◽  
Jan Steyaert ◽  
Federico Fogolari ◽  
Gennaro Esposito
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
Solution Structure ◽  
Chemical Shifts ◽  
Molecular Size ◽  
Side Chain ◽  
3D Nmr ◽  
Target Antigen ◽  
Internuclear Distances ◽  
2D And 3D

Background: Nanobodies, or VHHs, are derived from heavy chain-only antibodies (hcAbs) found in camelids. They overcome some of the inherent limitations of monoclonal antibodies (mAbs) and derivatives thereof, due to their smaller molecular size and higher stability, and thus present an alternative to mAbs for therapeutic use. Two nanobodies, Nb23 and Nb24, have been shown to similarly inhibit the self-aggregation of very amyloidogenic variants of β2-microglobulin. Here, the structure of Nb23 was modeled with the Chemical-Shift (CS)-Rosetta server using chemical shift assignments from nuclear magnetic resonance (NMR) spectroscopy experiments, and used as prior knowledge in PONDEROSA restrained modeling based on experimentally assessed internuclear distances. Further validation was comparatively obtained with the results of molecular dynamics trajectories calculated from the resulting best energy-minimized Nb23 conformers. Methods: 2D and 3D NMR spectroscopy experiments were carried out to determine the assignment of the backbone and side chain hydrogen, nitrogen and carbon resonances to extract chemical shifts and interproton separations for restrained modeling. Results: The solution structure of isolated Nb23 nanobody was determined. Conclusions: The structural analysis indicated that isolated Nb23 has a dynamic CDR3 loop distributed over different orientations with respect to Nb24, which could determine differences in target antigen affinity or complex lability.

scholarly journals On the preparation and NMR spectroscopic characterization of potassium aluminium tetrahydride KAlH4

2019 ◽  
Vol 21 (23) ◽  
pp. 12576-12584 ◽  
Author(s):  
Bodo Zibrowius ◽  
Michael Felderhoff
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
Spectroscopic Characterization ◽  
Mas Nmr ◽  
Isotropic Chemical Shift ◽  
Quadrupole Coupling ◽  
Coupling Parameters

Conventional 1D 27Al MAS NMR spectroscopy allows the isotropic chemical shift and the quadrupole coupling parameters of Pnma KAlH4 to be determined precisely.

A nuclear magnetic resonance investigation of the micellar properties of a series of sodium cyclohexylalkanoates

1999 ◽  
Vol 77 (11) ◽  
pp. 1994-2000 ◽  
Author(s):  
Judith A MacInnis ◽  
R Palepu ◽  
D Gerrard Marangoni
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
Conformational Changes ◽  
Chemical Shifts ◽  
Micelle Formation ◽  
Counterion Binding ◽  
Micellar Properties ◽  
Aggregation Numbers ◽  
Multinuclear Nmr Spectroscopy ◽  
Magnetic Resonance Investigation

The micellar properties of a family of surfactants, the sodium cyclohexylalkanoates, have been investigated in aqueous solution using multinuclear NMR spectroscopy. C-13 chemical shift measurements have been used to determine both the cmc values and the micellar aggregation numbers (Ns values) of these surfactants. The cmc values and the degrees of counterion binding were estimated from 23Na chemical shift measurements. The critical micelle concentrations (cmc's) and the aggregation numbers determined from the NMR experiments indicate that these amphiphiles have high cmc's and low aggregation numbers when compared to other single-headed surfactants (most notably the sodium alkanoates). The conformational changes incurred by the carbon atoms upon micelle formation have been deduced from the 13C chemical shift differences (δsurf,mic - δsurf,aq). These results are used to discuss the formation of the aggregates of the sodium cyclohexylalkanoate surfactants as a function of the length of the alkanoate side chain.Key words: micelles, surfactants, NMR spectroscopy, chemical shifts, aggregation numbers, degree of counterion binding, conformational changes.

Chemical shift correlated two-dimensional nmr spectroscopy and its application to solving the proton nmr spectra of oligoribonucleotides

1980 ◽  
Vol 58 (18) ◽  
pp. 1947-1956 ◽  
Author(s):  
Alex D. Bain ◽  
Russell A. Bell ◽  
Jeremy R. Everett ◽  
Donald W. Hughes
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
Nmr Spectra ◽  
Pulse Sequence ◽  
Chemical Shifts ◽  
Proton Nmr ◽  
Two Dimensional

An alternative two-dimensional nmr pulse sequence, (90°–t1/2–90°–t1/2–FID),correlates the chemical shifts of coupled nuclei. The application of this technique to the solution of the complicated proton nmr spectra of oligoribonucleotides is discussed.

A systematic investigation of the reaction of SiF2 with ethylene and six methyl-substituted ethylenes. I. Product yields and mechanistic conclusions

1980 ◽  
Vol 58 (5) ◽  
pp. 419-424 ◽  
Author(s):  
William F. Reynolds ◽  
James C. Thompson ◽  
A. P. Gerald Wright
Keyword(s):  
Nmr Spectroscopy ◽  
Ground State ◽  
Systematic Investigation ◽  
Quartz Tube ◽  
Open Chain ◽  
Product Yields ◽  
Chain Compounds

SiF2 produced by the quartz tube reaction has been reacted with ethylene and six methyl-substituted ethylenes. All major products (polymers, disilacyclobutanes, disilacyclohexanes, and open chain compounds) have been characterized by a combination of 19F, 1H, 13C, and 29Si nmr spectroscopy. While polymer is always formed in highest yield, the relative proportions of other products vary significantly from alkene to alkene.Key observations concerning structures and stereochemistries and product yields are summarized. Consideration of this evidence leads to a mechanism involving attack of SiF2 on the olefin to form an excited silirane which either ring opens or relaxes to its ground state, followed in either case by further reaction.

Solid-State Carbon-13 NMR Studies of Vulcanized Elastomers. VII. Sulfur-Vulcanized Cis-1,4 Polybutadiene at 75.5 Mhz

1989 ◽  
Vol 62 (5) ◽  
pp. 908-927 ◽  
Author(s):  
R. S. Clough ◽  
J. L. Koenig
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Chemical Shifts ◽  
Chemical Information ◽  
Chemical Probes ◽  
Nmr Studies ◽  
Nmr Characterization ◽  
The Individual ◽  
Insight Into

Abstract Solid-state C-13 NMR spectroscopy provides a wealth of chemical information concerning sulfur-vulcanized cis-l,4-polybutadiene. New resonances which appear upon curing have chemical shifts which are expected for crosslink and cyclic structures. The DEPT experiment with MAS worked well for the polybutadiene vulcanizate in the solid state. DEPT is very useful as an aid in the assignment of structures to resonances. The new resonances can be assigned to more than one type of structure given only chemical shift and DEPT information. Swelling measurements indicate the majority of the resonances are due to cyclics. Further work involving C-13 NMR characterization of polybutadiene vulcanizates treated with chemical probes and vulcanizates cured with organic accelerators should provide insight into the specific structures responsible for the individual resonances.

Application of Reverse Two-Dimensional 1H{15N} NMR Spectroscopy to the Characterization of Two Inorganic Compounds:

1987 ◽  
Vol 42 (6) ◽  
pp. 703-706 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Klaus Schamel ◽  
Karlheinz Guldner ◽  
Max Herberhold
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Shifts ◽  
Inorganic Compounds ◽  
Ring System ◽  
Coupling Constants ◽  
15N Nmr ◽  
Two Dimensional ◽  
Hydrogen Atoms ◽  
15N Nmr Spectroscopy

AbstractThe inorganic ring system linked to the [Cr(CO)5] fragment [R = tBu (1), NH2 (2)], has been studied by reverse two-dimensional, 2D, 1H{15N} NMR spectroscopy. In solution, the exchange of the N-H hydrogen atoms is slow on the NMR time scale. Chemical shifts δ(1H), δ(13C), δ(31P), δ(15N) and coupling constants 1J(31P1H), 2J(31P13C), 1J(31P15N) are reported. In the case of 2, the reduced coupling constants 2K(31PN1H) and 1K(31P15N) have the same sign.

Sign in / Sign up

Export Citation Format

Share Document