Lanthanide-induced Chemical Shifts Research Articles

Holmium complex with phospholipids as 1H NMR temperature probe for membrane systems.

The temperature dependence of the lanthanide-induced chemical shifts (LISs) was studied for the systems containing 1-palmitoyl-2-oleoylphosphatidylcholine (POPC)-Ho, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)-Ho and 1,2-dimyristoyl-sn-glycero-3-phosphorylcholine (DMPC)-Ho in unilamellar liposomes. In the POPC-Ho system, anti-Curie dependence of LISs is observed, same as previously observed in POPC-Pr system. In the DPPC- and DMPC-Ho systems, temperature features are observed which are probably connected with phase transition.

Thulium complex with DOPC as 1H NMR temperature sensor

The goal of the research was to show the limits within which Tm3+ can be used as a linear response probe in lipid membrane. Temperature dependence of lanthanide-induced chemical shifts (LISs) were studied using the example of DOPC phospholipid by means of NMR spectroscopy. It was demonstrated that these dependences have thermal feature, which could be connected with the changes of the structure of lanthanide-phospholipid complex (Tm-DOPC complex). The analysis of paramagnetic properties such as the temperature sensitivity of LIS indicates the prospect of using kinetically unstable lanthanide complexes as shifting temperature-sensitive probes for determining local temperature using MRI technologies.

Sensitization of Visible and NIR Emitting Lanthanide(III) Ions in Noncentrosymmetric Complexes of Hexafluoroacetylacetone and Unsubstituted Monodentate Pyrazole

A series of highly volatile eight-coordinate air and moisture stable lanthanide complexes of the type [Ln(hfaa)3(L)2] (Ln = Pr (1), Nd (2), Eu (3), Gd (4), Tb (5), Dy (6), Ho (7), Er (8), Tm (9), and Yb (10); hfaa = anion of hexafluoroacetylacetone and L = pyrazole) have been synthesized and characterized by elemental analysis, IR, ESI-MS(+), and NMR studies. Single-crystal X-ray structures have been determined for the Eu(III) and Dy(III) complexes. These complexes crystallize in the monoclinic space group P2(1)/c. The lanthanide ion in each of these complexes is eight-coordinate with six oxygen atoms from three hfaa and two N-atoms from two pyrazole units, forming a coordination polyhedron best describable as a distorted square antiprism. The NMR spectra reveal that both the pyrazole units remain attached to the metal in solution and the β-diketonate and pyrazole protons are shifted in opposite directions in the case of paramagnetic complexes. The lanthanide-induced chemical shifts are dipolar in nature. The hypersensitive transitions of Nd(III), Ho(III), and Er(III) are sensitive to the environment (solvent), which is reflected by the oscillator strength and band shape of these transitions. The band shape due to the hypersensitive transition of Nd(III) in noncoordinating chloroform and dichloromethane is similar to those of the typical eight-coordinate Nd(III) β-diketonate complexes. The quantum yield and lifetime of Pr(III), Eu(III), Tb(III), Dy(III), and Tm(III) in visible and Pr(III), Nd(III), Dy(III), Ho(III), Er(III) Tm(III), and Yb(III) in the NIR region are sizable. The environment around these metal ions is asymmetric, which leads to increased radiative rates and luminescence efficiencies. The quantum yield of the complexes reveal that ligand-to-metal energy transfer follows the order Eu(III) > Tb(III) ≫ Pr(III) > Dy(III) > Tm(III). Both ligands (hfaa and pyrazole) are good sensitizers for all the visible and NIR emitters effectively, except for Tb(III), Dy(III), and Tm(III), where pyrazole gave a negative effect (e.g., energy back-transfer) that is due to poor intramolecular energy transfer match. The good luminescent properties make these NIR-luminescent complexes to have potential application in optical communication, telecommunications, and fluoroimmunoassays.

NMR Studies of Mixed-Ligand Lanthanide (III) Complexes. Peculiarities of Molecular Structure, Dynamics and Paramagnetic Properties for Cerium Subgroup Chelates with Crown Ethers

The molecular structure, dynamics and paramagnetic properties of the complex cations [Ln(ptfa)2 (18-crown-6)]+ in deuterated toluene were studied for Ln = La, Ce, Pr and Nd. The activation enthalpy values of 68 ± 5, 55 ± 15 and 60 ± 13 kJ mol-1 for the 18-crown-6 conformationalinversion processes for the complexcations of Ce, Pr and Nd, respectively,were obtained. Quantitativeinvestigation of the lanthanide-induced chemical shifts shows a monotonic change of a spatial structure and magnetic susceptibility in comparison with the Bleaney predicted dependence. The free energy of molecular inversion activation for 18-crown-6 molecules in the complex cation [Ln(fod)2(18-crown-6)]+ is 74 ± 9 kJ mol-1 at 363 K, which is a little more than the value of the free energy of activation 64 ± 9 kJ mol-1 at 363 K in the complex cation [Ln(ptfa)2(18-crown-6)]+.

Assignments of 1H and 13C NMR resonances of some isoquinoline alkaloids

Aided by model compounds, lanthanide-induced chemical shifts (LIS) and 2D NMR, the assignment of 1H and 13C NMR resonances of several isoquinoline alkaloids is discussed and demonstrated. The results obtained necessitate a reversal of many 13C NMR assignments reported in the literature. LIS constitutes a valuable tool in assigning NMR resonances and is complementary to other techniques used for this purpose. For β-narcotine it also provides information on the topology of the compound in solution. The spectra of several isoquinoline alkaloids having different structural skeletons are described. These compounds may serve as model compounds in assigning resonances of related alkaloids.

Assignment of 1H and 13C NMR resonances of some isoquinoline alkaloids

Aided by model compounds and lanthanide-induced chemical shifts (LIS), the assignment of 1H and 13C NMR resonances of some isoquinoline alkaloids is discussed and demonstrated. Two-dimensional shift correlated NMR and 1H NOE difference experiments are used in order to assign all proton and carbon chemical shifts in an unambiguous way. Due to solubility problems LIS experiments are impossible for the quaternary compounds investigated. These compounds are studied using models and 2D NMR.

Constituents of Papaver bracteatum: O-methyl-α-thebaol and 10- n-nonacosanol. Lanthanide-induced chemical shifts in 1H NMR and 13C NMR

Two non-alkaloidal constituents were identified in Papaver bracteatum: O-methyl-α-thebaol and 10- n-nonacosanol. O-Methyl-α-thebaol is a new natural compound. The presence of isothebaine is confirmed. Lanthanide-induced chemical shifts can be used for the assignments of the 13C NMR chemical shifts of isothebaine and phenanthrenes. The use of lanthanide-induced chemical shifts in the identification of methoxyl resonances in 1H NMR is discussed.

A study of lanthanide p-toluene sulphonic acid complexes in solution

Lanthanide p-toluene sulphonic acid (ptsa) complexes were prepared for La, Pr, Nd, Sm, Eu, Dy, Ho, Er and Yb, and found to exist as Ln(ptsa) 3. Conductivity studies of La(ptsa) 3 in DMSO and DMF suggest 1:2 and, possibly, 1:1 electrolyte behaviour in these solvents, respectively. NMR lanthanide-induced chemical shifts (LIS) for aromatic protons in (ptsa) − and methyl protons in DMSO, were measured for all complexes as a function of the [Ln 3+[DMSO] in a medium consisting of CCl 4, DMSO, and CH 3CN. Analysis of the LIS data suggests a change in (ptsa) − coordination round Ln 3+ across the lanthanide series.

Calculation of NMR lanthanide-induced chemical shifts. The paradox of the pseudocontact model for europium reagents with coordination at the pyridine nitrogen atom

Calculation of NMR lanthanide-induced chemical shifts. The paradox of the pseudocontact model for europium reagents with coordination at the pyridine nitrogen atom

Lanthanide-induced chemical shifts of sulfonium salts

Lanthanide-induced chemical shifts of sulfonium salts

Lanthanide-induced chemical shifts and the relative stereochemistry of multistriatin, 2,4-dimethyl-5-ethyl-6,8-dioxabicyclo[3.2.1]octane

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLanthanide-induced chemical shifts and the relative stereochemistry of multistriatin, 2,4-dimethyl-5-ethyl-6,8-dioxabicyclo[3.2.1]octaneWilliam E. Gore and Ian M. ArmitageCite this: J. Org. Chem. 1976, 41, 11, 1926–1930Publication Date (Print):May 1, 1976Publication History Published online1 May 2002Published inissue 1 May 1976https://doi.org/10.1021/jo00873a008RIGHTS & PERMISSIONSArticle Views36Altmetric-Citations11LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (620 KB) Get e-Alerts Get e-Alerts

NMR Experiments on Cyclic Sulfites. VII. Lanthanide Induced Chemical Shifts in Trimethylene Sulfites with Respect to the Orientation of the S=O Bond.

NMR Experiments on Cyclic Sulfites. VII. Lanthanide Induced Chemical Shifts in Trimethylene Sulfites with Respect to the Orientation of the S=O Bond.

Lanthanide-induced Chemical Shifts in Proton NMR Spectra of 5,5-Dimethyl-2-oxo-1,3,2-dioxaphosphorinanes.

Lanthanide-induced Chemical Shifts in Proton NMR Spectra of 5,5-Dimethyl-2-oxo-1,3,2-dioxaphosphorinanes.

Structure differentiation by means of lanthanide-induced nitrogen-14 chemical shifts

Structure differentiation by means of lanthanide-induced nitrogen-14 chemical shifts

Carbon magnetic resonance. Signal assignment by alternately pulsed nuclear magnetic resonance and lanthanide-induced chemical shifts

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCarbon magnetic resonance. Signal assignment by alternately pulsed nuclear magnetic resonance and lanthanide-induced chemical shiftsOtto A. Gansow, M. R. Willcott, and R. E. LenkinskiCite this: J. Am. Chem. Soc. 1971, 93, 17, 4295–4297Publication Date (Print):August 1, 1971Publication History Published online1 May 2002Published inissue 1 August 1971https://doi.org/10.1021/ja00746a037RIGHTS & PERMISSIONSArticle Views75Altmetric-Citations32LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (347 KB) Get e-Alerts Get e-Alerts