NMR Of Solids Research Articles

Spreading DANTE's wings: selective excitation of deuterium powder patterns

2H NMR of static polycrystalline or amorphous solids often yields broad Pake powder patterns. These broad powder patterns arise from the orientation dependence of the second-rank quadrupolar Hamiltonian and the inherent orientational anisotropy of the sample. Here is presented an experiment that selectively excites a subset of the orientations of the quadrupolar Hamiltonian to give high-resolution spectra.

Nuclear magnetic resonance spectroscopy

Fundamental Principles. L.W. Jelinsky, Experimental Methods. The Chemical Shift. Coupling of Nuclear Spins. Nuclear Relaxation and Chemical Rate Processes. P.A. Mirau and F.A. Bovey, Two-Dimensional Nuclear Magnetic Resonance Spectroscopy. Macromolecules. NMR of Solids. F.A. Bovey, L.W. Jelinsky, P.A. Mirau, Special Topics. Appendixes. Author Index. Subject Index.

Selective excitation and quadrupole connectivities in deuterium NMR of paramagnetic solids

Selective excitation and quadrupole connectivities in deuterium NMR of paramagnetic solids

Oxygen-17 NMR in solids by dynamic-angle spinning and double rotation

IT is widely lamented that despite its unqualified success with spin-1/2 nuclei such as 13C, 29Si and31P, the popular NMR technique of magic-angle spinning (MAS) has experienced a somewhat restricted applicability among quadrupolar nuclei such as 17O, 23Na and 27A1 (refs 1–3). The resolution in the central (1/2 ⇆–1/2) transition of these non-integer quadrupolar spins under MAS is thought to be limited primarily by second-order quadrupolar broadening. Such effects of second-order spatial anisotropy cannot be eliminated by rotation about a fixed axis or by multiple-pulse techniques4,5. More general mechanisms of sample reorientation (refs 6–8 and A. Samoson and A. Pines, manuscript in preparation) can, however, make high-resolution NMR of quadrupolar nuclei feasible. MAS is implemented by spinning a sample about a single axis so that second-rank spherical harmonics (which give rise to first-order broadening through anisotropy of electrical and magnetic interactions) are averaged away. But dynamic-angle-spinning (DAS) and double-rotation (DOR) NMR involve spinning around two axes, averaging away both the second- and fourth-rank spherical harmonics, which are responsible for second-order broadening. Here we present the application of these new techniques to 17O in two minerals, cristobalite (SiO2) and diopside (CaMgSi2O6). This work goes beyond previous results on 23Na (ref. 8) by showing the first experimental results using DAS and by demonstrating the application of DOR to the resolution of distinct oxygen sites in an important class of oxide materials.

Frequency-switched pulse sequences: Homonuclear decoupling and dilute spin NMR in solids

A new rf pulse sequence is described for the decoupling of homonuclear dipolar interactions in solid state NMR. It involves alternate 2π rotations of opposite signs about the magic-angle axis in spin space, by π rf phase shifts synchronous with rapid switching of the rf carrier frequency between opposite sides of resonance; the frequency offsets and the rf field intensity satisfy the Lee-Goldburg coherent averaging condition. Direct digital frequency synthesis ensures phase coherence. The pulse sequence has significant advantages over previous methods in the case that abundant spins are irradiated while dilute spins are observed, in an experiment measuring heteronuclear spin-spin couplings.

SEMUT Spectral editing and determination of radiofrequency field strengths for 13C CP/MAS NMR of solids

SEMUT Spectral editing and determination of radiofrequency field strengths for 13C CP/MAS NMR of solids

Deuteron two-dimensional exchange NMR in solids

The deuteron two-dimensional exchange experiment for the study of slow molecular motions in polycrystalline and amorphous solids is presented. A pair of four-pulse sequences for obtaining pure phase 2D spectra of a spin I = 1 system and phase cycles for minimizing artifacts are derived from spin dynamics calculations. A comprehensive description of the experiment and the 2D data processing is given. The information content of 2D exchange spectra of powders is discussed. For discrete jump motions, 2D powder spectra exhibit characteristic ridge patterns originating from the singularities of the 2D lineshape. From the geometry of such ridge patterns the angles of reorientation of the electric field gradient tensors can be determined directly, thus yielding information about the type of motion. The method is illustrated by two examples: the two-site jump of dimethyl sulfone and the six-site jump of hexamethylbenzene.

Slice-selection method for topical NMR in solids

A method to perform NMR and relaxation measurements in narrow slices or lines of a solid is described. The method is based on acquisition and averaging of free induction decays with stepped field gradients. An FID signal is recorded for a given gradient; after a time of the order of T 1 another gradient is applied and the FID is coadded to the previous one, et cetera. The method has the peculiarity of requiring H 1 only of the order of the intrinsic linewidth while the maximum gradient can be increased up to a value giving offsets much larger than H 1.

Evaluation of degree of hydration in concrete using 29Si magic angle spinning NMR in solids

The degree of hydration of cement and concrete can be followed using 29Si MAS-NMR. Preliminary results of the effects of hydration on the distribution of silicate polymers in concretes of known mix designs, as well as the constituent cement, are presented. The spectra of the sand and aggregate used are also given. The technique appears promising as a means of monitoring concrete silicate anion structure and its possible correlation with mechanical properties.

Perspectives in high-resolution solid-state nuclear magnetic resonance, with emphasis on combined rotation and multiple-pulse spectroscopy

Recent trends of general interest in high-resolution NMR of solids are mentioned, and some examples briefly discussed. Stress is laid on the use of the multiple-pulse technique, particularly when combined with magic-angle spinning to give CRAMPS. Two studies of proton CRAMPS are described, one concerning hydrogen bonding in carboxylic acids and the other involving phosphonic acid derivatives. The relationship between proton isotropic chemical shifts and hydrogen-bond distances is explored in some detail. A clear correlation is found.

ChemInform Abstract: CP/MAS 125Te NMR in Solids: An Example of 125Te‐35,37Cl J Coupling

ChemInformVolume 18, Issue 43 Physical Organic Chemistry ChemInform Abstract: CP/MAS 125Te NMR in Solids: An Example of 125Te-35,37Cl J Coupling M. J. COLLINS, M. J. COLLINS Div. Chem., Natl. Res. Counc. Can., Ottawa, Ont. K1A 0R9, Can.Search for more papers by this authorJ. A. RIPMEESTER, J. A. RIPMEESTER Div. Chem., Natl. Res. Counc. Can., Ottawa, Ont. K1A 0R9, Can.Search for more papers by this authorJ. F. SAWYER, J. F. SAWYER Div. Chem., Natl. Res. Counc. Can., Ottawa, Ont. K1A 0R9, Can.Search for more papers by this author M. J. COLLINS, M. J. COLLINS Div. Chem., Natl. Res. Counc. Can., Ottawa, Ont. K1A 0R9, Can.Search for more papers by this authorJ. A. RIPMEESTER, J. A. RIPMEESTER Div. Chem., Natl. Res. Counc. Can., Ottawa, Ont. K1A 0R9, Can.Search for more papers by this authorJ. F. SAWYER, J. F. SAWYER Div. Chem., Natl. Res. Counc. Can., Ottawa, Ont. K1A 0R9, Can.Search for more papers by this author First published: October 27, 1987 https://doi.org/10.1002/chin.198743045Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume18, Issue43October 27, 1987 RelatedInformation

Separated-local-field measurements using low-power multipulse decoupling

The separated-local-field experiment in the NMR of solids is used to measure the strength of the static dipolar interaction between isolated heteronuclear spin pairs (Z3). In the case of static solids, the strength of the dipolar interaction can be used to calculate the heteronuclear interatomic distance (4). Alternatively, in the presence of some molecular motion and a known interatomic distance, the reduction of the strength of the heteronuclear dipolar interaction due to that motion can be used to obtain information about the amplitudes of those molecular motions (3). Techniques to obtain this local-field information are two-dimensional experiments which contain the usual preparation, evolution, and detection periods. During the Preparation period, the spin system comes to equilibrium; then observe spin magnetization is generated (usually by means of Hartmann-Hahn cross polarization). In the second period, the magnetization is allowed to evolve for a time t, while the coupled heteronuclei are subjected to a homonuclear decoupling, allowing heteronuclear interactions to survive. In the final period, t2, the observe nuclei are detected under full heteronuclear decoupling. For this two-dimensional experiment, the t, increment is a cycle of some appropriate homonuclear decoupling scheme, usually WAHUHA (5) or MREV-8 (68). These “windowed” sequences, however, require very high power levels in order to obtain reasonable results. Typically, RF fields greater than 2 mT, cortespomimg to a 90” pulse length of less than three microseconds, are required to homodecouple protons. This demanding requirement is generally not available to the routine or casual solids NMR spectroscopist. This report describes a version of the separated-locall the usual WAHUHA homondear decoupling pulse train has been replaced by the more efficient windowless BLEW12 (9) sequence. Also, the time interval between cross polarization and the refocusing pulse was not constrained to be an integer number of multipulse cycles. For this work, a half-cycle of BLEW-12 is used as the tl increment time. The half-cycle represents the minimum pulse sequence necessary to cause zero-order dipolar interactions to vanish (9).

Book Review: Transient Techniques in NMR of Solids. An Introduction to Theory and Practice. By B. C. Gerstein and C. R. Dybowski and C. R. Dybowski

Book Review: Transient Techniques in NMR of Solids. An Introduction to Theory and Practice. By B. C. Gerstein and C. R. Dybowski and C. R. Dybowski

CP/MAS tellurium-125 NMR in solids: an example of 125Te-35,37Cl J coupling

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCP/MAS tellurium-125 NMR in solids: an example of 125Te-35,37Cl J couplingMichael J. Collins, John A. Ripmeester, and Jeffery F. SawyerCite this: J. Am. Chem. Soc. 1987, 109, 13, 4113–4115Publication Date (Print):June 1, 1987Publication History Published online1 May 2002Published inissue 1 June 1987https://doi.org/10.1021/ja00247a047RIGHTS & PERMISSIONSArticle Views269Altmetric-Citations45LEARN 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 (422 KB) Get e-Alerts Get e-Alerts

High-resolution calcium-43 NMR in solids

The resolution afforded by alkaline earth ion NMR in solution is often insufficient to obtain individual lines for chemically distinct sites, particularly in macromolecular environments (Z-4). The problem inherent in a small chemical shift range of about 70 ppm is aggravated further by broadening associated with the often complex spin relaxation driven by the nuclear electric quadrupole interactions with fluctuating electric field gradients (5). The dynamical part of the broadening may be defeated if the nucleus to be observed is immobilized. The solid-state experiment has been successful on a number of nonintegral spin quadrupole nuclei where the central (+f c-) -1) transition is exploited and the residual second-order quadrupole broadenings are minimized by rapid sample rotation at the magic angle (6-9). However, the possible gain in resolution is made at the cost of decreased sensitivity because only the central transition in a ; or $ manifold is observed (IO). In principle, the loss may be regained using magnetization-transfer methods such as those exploited by Pines, Gibby, and Waugh (II). Double-resonance approaches have been discussed for calcium fluoride (12,13), and a direct detection of calcium-43 reported using adiabatic demagnetization methods at low temperature (14). We report here observation of the high-resolution calcium-43 NMR spectrum using CP-MASS methods which demonstrates the feasibility of the more routine experiment in a noncubic environment and defines several of the critical experimental parameters. Figure 1 shows the CP-MASS calcium-43 NMR spectrum of calcium acetate obtained at 4.7 T using a spectrometer constructed in this laboratory. The relevant experimental parameters are summarized in the caption. The proton-calcium doubleresonance probe employed a Doty Scientific stator and rotor coupled to the proton tuning elements using a half wavelength coaxial line tapped at the proton null point for injection and detection of the calcium-43 resonance frequency. The spectrometer used Amplifier Research (AR-200L) and Henry Radio power amplifiers, Nicolet-GE 1280 data system, and a quadrature receiver built in the laboratory. The phase-shifting circuitry was designed after a very similar version by Robert MacKay, Monsanto Chemical Company. The match for the magnetization transfer was found by changing the power level on the calcium side while keeping the proton field fixed at 46 kHz; the optimum cross-polarization rate was found when the strength of the calcium rf field was approximately the same as that which gave w1 for calcium of 45 kHz in a saturated aqueous solution of calcium chloride. For calcium acetate, optimum contact times were long, in the tens of milliseconds range as shown in Fig. 2.

ChemInform Abstract: Low‐Temperature 13C NMR in Solids. Part 7. Methyl Carbons

ChemInformVolume 18, Issue 10 Physical Organic Chemistry ChemInform Abstract: Low-Temperature 13C NMR in Solids. Part 7. Methyl Carbons M. S. SOLUM, M. S. SOLUM Dep. Chem., Univ. Utah, Salt Lake City, UT 84112, USASearch for more papers by this authorJ. C. FACELLI, J. C. FACELLI Dep. Chem., Univ. Utah, Salt Lake City, UT 84112, USASearch for more papers by this authorJ. MICHL, J. MICHL Dep. Chem., Univ. Utah, Salt Lake City, UT 84112, USASearch for more papers by this authorD. M. GRANT, D. M. GRANT Dep. Chem., Univ. Utah, Salt Lake City, UT 84112, USASearch for more papers by this author M. S. SOLUM, M. S. SOLUM Dep. Chem., Univ. Utah, Salt Lake City, UT 84112, USASearch for more papers by this authorJ. C. FACELLI, J. C. FACELLI Dep. Chem., Univ. Utah, Salt Lake City, UT 84112, USASearch for more papers by this authorJ. MICHL, J. MICHL Dep. Chem., Univ. Utah, Salt Lake City, UT 84112, USASearch for more papers by this authorD. M. GRANT, D. M. GRANT Dep. Chem., Univ. Utah, Salt Lake City, UT 84112, USASearch for more papers by this author First published: March 10, 1987 https://doi.org/10.1002/chin.198710067Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume18, Issue10March 10, 1987 RelatedInformation

First observation of 5-coordinate aluminum by MAS aluminum-27 NMR in well-characterized solids

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFirst observation of 5-coordinate aluminum by MAS aluminum-27 NMR in well-characterized solidsLawrence B. Alemany and Garry W. KirkerCite this: J. Am. Chem. Soc. 1986, 108, 20, 6158–6162Publication Date (Print):October 1, 1986Publication History Published online1 May 2002Published inissue 1 October 1986https://doi.org/10.1021/ja00280a008RIGHTS & PERMISSIONSArticle Views461Altmetric-Citations111LEARN 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 (639 KB) Get e-Alerts Get e-Alerts

ChemInform Abstract: HIGH‐RESOLUTION CARBON‐13 NMR OF RETINAL DERIVATIVES IN THE SOLID STATE

I3C NMR spectra of a large number of crystalline retinal derivatives have been obtained by using cross-polarization and magic-angle sample spinning. Most derivatives yield spectra with narrow lines (width around 20 Hz) which can be assigned via their 13C-'H dipolar coupling, their chemical shift tensors, comparison with solution spectra, or specific labeling. Measurement of the rotational sideband intensities in the spectra permit calculation of the chemical shielding tensors, and these data have allowed us to analyze variations in isotropic shifts of these compounds in more detail. We show that the tensors exhibit an odd/even effect which results from the steric crowding on one side of the polyene chain, that *-electron perturbations affect primarily the in-plane elements of the tensor, and, conversely, that strong steric interactions due to cis-trans isomerization affect the out-of-plane element. Finally, we observe a downfield shift at the C-5 position on isomerization about the 6-7 bond, and thus deduce from the observed shifts that retinal derivatives are 25-30% 6-s-trans in solution. The polyene aldehyde all-trans-retinal and its geometrical isomers play a central role in rhodospin and other visual and in bacteriorhodopsin and other light-driven membrane pump^.^^^ In both types of systems, photon-induced isomerization is the initial event of light tran~duction.~~~ However, in neither case are the spectroscopic properties of the intact protein similar to those of the free aldehydes, or of simple model compounds derived from it. Clearly, therefore, the conformational and electronic properties of the chromophores are strongly modulated by the approtein, and an understanding of the differences between bacteriorhodospin and rhodospin on the one hand, and retinal and its derivatives on the other, is crucial to an understanding of the entire system. For some years, I3C NMR has been used sporadically to in- vestigate both retinal derivatives and retinal-containing proteins. Initially, solution NMR techniques were applied to detergent- solubiIized rhodospin and bacteriorhodop~in,~~~ but the spectra obtained by using this approach were both of poor quality and prone to artifacts. The problems resulted from the extreme measures necessary to achieve short rotational correlation times in solution for what are both intrinsic membrane proteins. A more logical approach is to use the methodology of high-resolution dilute-spin NMR of solids, namely cross-polarization combined with magic-angle sample spinning (MASS),9 to study the intact membranes. This not only provides higher quality data but also permits examination of the anisotropic NMR interactions which

High resolution CPMAS 13C NMR of organometallic solids. Observation of J coupling to tin

Chemical shift and 1 J( 117,119Sn, 13C) data from cross polarization magic angle spinning (CPMAS) proton-decoupled solid-state 13C NMR experiments are given for the methyltin carbon in (Me 2SnS) 3, Me 3SnOAc, Me 2S(acetylacetonate) 2, Me 2SnCl 2· 2(dimethylsulfoxide), and amorphous (Me 2SnO) n . The relationship between the magnitude of the coupling constant and the coordination at tin is examined by reference to X-ray structure data. The tin-methyl 13C chemical shift was sensitive to slight variations in bond angles and bond lengths. The presence of isotopically abundant NMR-active nuclei in the molecule broadens lines, and can prevent resolution of the J coupled interaction.

High-resolution solid-state NMR of phosphorus-fluorine compounds

The significance of NMR for chemists is based on the highly specific relations between the observable NMR parameters chemical shift δ (or magnetic shielding σ) and spin-spin coupling J and the electronic environment of the resonance nucleus. The directionality of covalent bonds causes aniso- tropies of σ and J described by the tensors σ ii and J ii. Due to the rapid reorientation of molecules in liquid phases only the popular isotropic mean values σ and J can be observed. In contrast to this ‘degenerate case’ [1] the up-to-date high-resolution NMR in solids provides exact tensor data and therefore gives fundamental new answers to old questions. Using high magnetic fields (B o = 6.4 T) in combination with magic angle sample spinning we measured the 31P shielding ( σ , Δσ, η σ ) and coupling ( J , ΔJ, η J = 0) tensor data for monofluorophosphates. ▪ The data reflect bonding and symmetry of the PO 3F groups as well as the non-equivalence of the P atoms in the dimeric anion. Comparison with condensed phosphates ( cf. table) shows the correspondence of the ligand atoms fluorine and bridging oxygen.