Probe of cadmium(II) binding on soil fulvic acid investigated by 113Cd NMR spectroscopy

1996 ◽  
Vol 74 (7) ◽  
pp. 1360-1365 ◽  
Author(s):  
Kun H. Chung ◽  
Seog W. Rhee ◽  
Hyun S. Shin ◽  
Christopher H. Moon
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
Acrylic Acid ◽  
Benzoic Acid ◽  
Fulvic Acid ◽  
Binding Sites ◽  
Chemical Shifts ◽  
Cadmium Concentration ◽  
Synthetic Polymers ◽  
Cadmium Complexes

Binding of cadmium(II) on soil fulvic acid (FA) was investigated over a range of fulvate-to-cadmium concentration ratios (8 – 59 equiv. mol−1) using 113Cd NMR spectroscopy. The 113Cd chemical shift of cadmium bound on fulvate was observed in a more downfield region (δ −20.4 to −15.6) than that bound on synthetic polymers, poly(acrylic acid) (PAA: δ −36.6 to −38.2), poly(methacrylic acid) (PMAA: δ −34.0 to −25.4), and poly(vinyl benzoic acid) (PVBA: δ −34.7 to −31.2). The calculated values of individual chemical shifts for the species CdL+ and CdL2 (L: carboxylate) formed in Cd(II)–carboxylate systems (e.g., acetate, benzoate) are δ −22 to −24 and δ −39 to −40, respectively. The relative downfield shift of cadmium(II)–fulvate suggests that functional groups (e.g., hydroxyl and neutral N donor) other than carboxylates may be involved in cadmium coordination. The chemical shifts of cadmium complexes of hydroxycarboxylates (e.g., glycolate) or carboxylates containing neutral N donor (e.g., picolinate) were generally observed in more downfield regions than their carboxylate counterparts. Key words: fulvic acid, polyfunctionality, binding sites, chemical shift, 113Cd NMR.

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.

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.

Origin and Nature of Transmission Modes of Anomalous Effects of meta-Substituents on the 13C Chemical Shift of the Carboxyl Carbon (δCO) of Benzoic Acid

2010 ◽  
Vol 63 (2) ◽  
pp. 321 ◽  
Author(s):  
Susanta K. Sen Gupta ◽  
Rajendra Prasad
Keyword(s):  
Chemical Shift ◽  
Benzoic Acid ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Basis Set ◽  
Benzoic Acids ◽  
Anomalous Effect ◽  
Atomic Orbitals ◽  
13C Chemical Shift ◽  
Carboxyl Carbon

Studies of substituent effects on NMR chemical shifts are of great benefit in determining fine details of electron distribution in molecules. Interestingly, NMR substituent effects are often different and even opposite to those associated with chemical reactivity. Among molecules exhibiting anomalous (reverse) substituent effects is benzoic acid, the standard model for studying substituent effects. The substituent effect on the 13C chemical shift of its carboxyl carbon (δ CO) is just the opposite of that on its acid strength or reactivity. To develop insights into the origin of the anomalous effect of a substituent on δ CO, occupancies of natural atomic orbitals at the carboxyl and ring carbons of a set of 10 meta-substituted benzoic acids have been calculated at the density functional theory level using the B3LYP function with split valance 6–311G++** basis set. Statistical correlations obtained for the 13C chemical shifts, δ CO and δ C-ring of these benzoic acids with the natural atomic orbital occupancies calculated for respective carbon atoms on one hand and with Taft’s inductive and resonance parameters (σ I and σ R BA ) of the substituents on the other hand have been critically analyzed. The findings have established firmly that a meta-substituent’s anomalous effect on δ CO is caused by the substituent-induced changes in the total occupancy of only the p z natural atomic orbitals at the carboxyl carbon. The study has demonstrated further that the transmission of the anomalous effect can be successfully interpreted by a 5.5:–2.5:1 combination of the localized, extended, and resonance-induced π-polarization effects.

9Be nuclear magnetic resonance spectroscopy trends in discrete complexes: an update

2020 ◽  
Vol 75 (5) ◽  
pp. 459-472 ◽  
Author(s):  
Jenna K. Buchanan ◽  
Paul G. Plieger
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Chemical Shifts ◽  
Solution Nmr ◽  
Resonance Spectroscopy ◽  
Coordination Numbers ◽  
Solution Nmr Spectroscopy ◽  
Beryllium Complexes

Abstract9Be solution NMR spectroscopy is a useful tool for the characterisation of beryllium complexes. An updated comprehensive table of the 9Be NMR chemical shifts of beryllium complexes in solution is presented. The recent additions span a greater range of chemical shifts than those previously reported, and more overlap is observed between the chemical shift regions of four-coordinate complexes and those with lower coordination numbers. Four-coordinate beryllium species have smaller ω1/2 values than the two- and three-coordinate species due to their higher order symmetry. In contrast to previous studies, no clear relationship is observed between chemical shift and the size and number of chelate rings.

scholarly journals Use of 95Mo NMR Spectroscopy as a New Approach to Structural Analysis of Diamagnetic Molybdenum Complexes

1976 ◽  
Vol 31 (5) ◽  
pp. 454-456 ◽  
Author(s):  
O. Lutz ◽  
A. Nolle ◽  
P. Kroneck
Keyword(s):  
Fourier Transform ◽  
Nmr Spectroscopy ◽  
Structural Analysis ◽  
Chemical Shift ◽  
Chemical Shifts ◽  
Oxidation States ◽  
New Approach ◽  
Molybdenum Complexes ◽  
Experimental Parameters

Abstract Fourier Transform NMR measurements of 95Mo and 97Mo are reported for several molybdenum compounds in different oxidation states. Using the molybdate ion as a reference, chemical shifts from about +500 ppm to about -1900 ppm have been observed. Experimental parameters and a chemical shift scale are given.

A 139La NMR study of the interactions between the La(III) cation and D-ribose in aqueous solution

1994 ◽  
Vol 72 (7) ◽  
pp. 1753-1757 ◽  
Author(s):  
Zhigang Chen ◽  
Nicole Morel-Desrosiers ◽  
Jean-Pierre Morel ◽  
Christian Detellier
Keyword(s):  
Aqueous Solution ◽  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
Stability Constant ◽  
Chemical Shifts ◽  
Similar Treatment ◽  
Calorimetric Measurements ◽  
Nmr Study ◽  
The Stability ◽  
Good Agreement

The interactions of the La(III) cation with D-ribose and with D-arabinose in aqueous solution were investigated by 139La NMR spectroscopy. In the case of D-ribose, the formation of a La(III)-sugar complex was indicated by variations of the 139La chemical shift and linewidth with an increase of the sugar concentration in solution. In contrast, the complexation of La(III) by arabinose is very weak and almost undetectable by 139La NMR. On the basis of a 1:1 stoichiometry, the stability constant for the complex of La(III) with D-ribose was calculated from the observed 139La chemical shift values. A similar treatment was done for the viscosity corrected 139La linewidths using arabinose as an uninteractive reference. The stability constants, K, obtained independently from 139La chemical shifts and linewidths are in good agreement, 2.8 ± 0.5 and 2.2 ± 0.6 M−1 respectively at 299.0 ± 0.5 K. The thermodynamic parameters for the complexation of La(III) by D-ribose could also be obtained: ΔH0 = −12 ± 2 kJ mol−1, and ΔS0 = −31 ± 5 J K−1 mol−1. These values are in very good agreement with those obtained by calorimetric measurements.

NMR effective radius of hydrogen in XIV group hydrides evaluated by NMR spectroscopy

2017 ◽  
Vol 46 (41) ◽  
pp. 14094-14097 ◽  
Author(s):  
M. Benedetti ◽  
F. De Castro ◽  
A. Ciccarese ◽  
F. P. Fanizzi
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
Chemical Shifts ◽  
Effective Radius ◽  
Nmr Chemical Shift ◽  
Ionic Radii ◽  
Nmr Chemical Shifts

In the [ABrnIm] (A = C, Si, Ge, Sn; n + m = 4) compounds, with the heavier halido ligands bonded to the central IV group elements, the 13C, 29Si, 73Ge and 119Sn NMR chemical shifts were found to be linearly related to the bonded halides ionic radii overall sum, ∑(rh). The 207Pb NMR chemical shift of the unstable [PbH4] hydride could be calculated.

scholarly journals Peculiarities of NMR 13C spectra of benzoic acid and saturated alkylbenzoates. I. Chemical shift of benzoyl fragment hydrocarbon atoms

2008 ◽  
Vol 2 (2) ◽  
pp. 77-83
Author(s):  
Volodymyr Mizyuk ◽  
◽  
Volodymyr Shibanov ◽  
Lesya Kobrin ◽  
Galyna Marshalok ◽  
...  
Keyword(s):  
Chemical Shift ◽  
Carbon Atom ◽  
Benzoic Acid ◽  
Alkyl Radical ◽  
Chemical Shifts ◽  
Degree Of Branching ◽  
Alkoxyl Group

It has been shown that chemical shift of 5 types of carbon nuclei of benzoyl fragment in saturated alkylbenzoates depends upon alkyl radical degree of branching near α-carbon atom of alkoxyl group. Typical values of chemical shifts of five nuclei for primary, secondary and tertiary alkylbenzoates have been admitted

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