Thursday, January 17, 2008

Bryan's Literature Update Through January 17, 2008

Welcome to another exciting Solid-State NMR Literature Blog update! Tell your friends all about the thrills and chills entailed in this wonderful read! It's a real page-turner (or page-scroller, get it?)! LOLZ!

This update contains all the news fit to print in the solid-state NMR (and some general NMR) world from Chem. Phys., Chem. Phys. Lett., Can. J. Chem., Chem. Commun., Dalton Trans., and J. Mater. Chem.. Six journals, six months, all below.

Special feature: Try moving your mouse cursor over the "volume" word in blog updates from Chemical Physics or Chem. Phys. Lett.. If you're at the University of Windsor, you can go right to the journal.


Chemical Physics

Vol: 337, Issue: 1-3, August 16, 2007

pp. 144-150

Title: A first-principles computational 17O NMR investigation of metal ion-oxygen interactions in carboxylate oxygens of alkali oxalates

Authors: Wong, A.; Thurgood, G.; Dupree, R.; Smith, M.E.

Keywords: DFT calculations; Metal ion-oxygen interactions; Oxalates; 17O NMR; Chemical anisotropy shifts; Electrical-field gradients

Abstract (English): 17O NMR parameters, including chemical shift (CS) and electrical-field gradient (EFG) tensors, are calculated for oxalate compounds containing various different alkali ions using a DFT infinite periodic solid approach. This DFT study allows correlations to be found between the metal ion and oxygen interaction and the 17O NMR interaction parameters. The 17O CS shows greater sensitivity to the local alkali ions than that shown by the 13C CS in the same compounds. It is found that the combination of metal ion-oxygen bond strength and cation size induce a deshielding shift up to ~70ppm of 17O diso. The results also show the effects of different M-O interactions and C-O bond characteristics on the orientation of 17O CS tensor components, and suggest that the 17O quadrupolar parameters are systematically sensitive to the local cation environments around the carboxylate oxygen.


Can. J. Chem. 85(7-8): 496–505 (2007) doi:10.1139/V07-069 © 2007 NRC Canada

Title: EFGShield - A program for parsing and summarizing the results of electric field gradient and nuclear magnetic shielding tensor calculations

Authors: Samyuktha Adiga, Dominic Aebi, and David L. Bryce

Abstract: A computer program (EFGShield) is described that simplifies and summarizes the output from electric field gradient (EFG) and nuclear magnetic shielding tensor calculations performed independently using existing quantum chemical software. In addition to summarizing tensor magnitudes according to conventions commonly used by solid-state NMR spectroscopists, the program provides Euler angles relating the orientations of the EFG and shielding tensor principal axis systems (PAS). An atomic coordinate file is generated that also contains dummy atoms representing the orientations of the EFG and shielding tensor PASs in the molecular framework. We demonstrate the functionality of the program using calculations of the chlorine EFG and shielding tensors for strontium chloride dihydrate and calcium chloride dihydrate. Several models of the chloride environment in these compounds are tested, including those where point charges are used to represent the extended three-dimensional lattices within the self-consistent charge field perturbation approach. The results highlight both the shortcomings and successes of traditional localized orbital-based basis sets in the description of the NMR properties of extended systems. We anticipate that EFGShield will be a useful tool for spectroscopists using quantum chemical software to aid in the interpretation of experimental data.

Key words: quantum chemical calculations, computer program, electric field gradient tensor, quadrupolar coupling constant, nuclear magnetic shielding tensor, Euler angles, alkaline earth chloride hydrates.


Can. J. Chem. 85(10): 782–792 (2007) doi:10.1139/V07-085 © 2007 NRC Canada

Title: High resolution O 1s XPS spectral, NMR, and thermodynamic evidence bearing on anionic silicate moieties (units) in PbO-SiO2 and Na2O-SiO2 glasses

Authors: H. W. Nesbitt and K. N. Dalby

Abstract: Recent technical advances in X-ray photoelectron spectroscopy (XPS) have largely overcome differential charging of insulator surfaces, with the result that O 1s linewidths for silicates can be routinely collected that are 50% to 100% narrower than had been previously obtainable. The bridging and nonbridging oxygen signals of glasses are well resolved and now can be accurately measured by XPS without resorting to ad hoc fitting procedures. All O 1s spectra of silicates collected so far are somewhat asymmetric to the high binding energy side of the peak, a characteristic due primarily to vibrational contributions in the ion state produced by photoemission (electronic excited state). This asymmetry must be considered if the proportion of bridging to nonbridging oxygen ratios are to be accurately determined from the XPS O 1s spectra of silicates. X-ray photoelectron spectroscopy (XPS) and nuclear magnetic resonance (NMR) experiments yield similar silicon-bridging oxygen (Si-O-Si) concentrations for PbO-SiO2 glasses. The data are proof that the reaction, 2PbO + SiO2 Pb2SiO4, does not go to completion (i.e., one or other reactant is not completely consumed). Instead, the data indicate that an equilibrium exists among these constituents, with the equilibrium constant for the reaction being near 15; ergo, some metal bridging oxygen (MBO or Pb-O-Pb), silicon bridging oxygen (BO or Si-O-Si), and nonbridging oxygen (NBO or M-O-Si) are present over the entire range of binary melt compositions. NMR and XPS spectroscopic techniques yield substantially different Si-O-Si concentrations in Na2O-SiO22O content. XPS experiments indicate higher proportions of Si-O-Si in Na2O-rich glasses than do the NMR studies. In spite of the different results, three independently collected sets of NMR experiments are similar and yield similar Si-O-Si concentrations. Five XPS experimental studies are likewise self-consistent (but different from the NMR studies). Comparison of data from the two spectroscopic techniques indicates that all experimental spectra are of good or reasonable quality, so that systematic experimental problems or the interpretation (i.e., fitting) of these spectra may be incorrect for one or both types of spectral data. Viscosity, conductivity, and the XPS data are consistent with (but not proof for) formation of an Na2Si2O5 species in the Na2O-SiO2 glasses. The most comprehensive NMR study is, by contrast, consistent with the formation of an orthosilicate species (Na4SiO4). The NMR and XPS results cannot yet be reconciled and additional experimental studies are required to resolve and to understand better Na2O-SiO2 liquids and glasses.

Key words: XPS, high resolution, silicate glass, NMR.


Chem. Commun., 2007, 2923 - 2925, DOI: 10.1039/b705844f

Title: Responsive fluorinated lanthanide probes for 19F magnetic resonance spectroscopy

Authors: P. Kanthi Senanayake, Alan M. Kenwright, David Parker and Susanna K. van der Hoorn

Abstract: The introduction of CF3 reporter groups close to the paramagnetic centre in macrocyclic lanthanide(III) complexes allows faster acquisition of 19F magnetic resonance data, and amplifies chemical shift non-equivalence, as exemplified by the definition of ratiometric chemical shift probes for pH and, in principle, enzyme activity.


Chem. Commun., 2007, 3664 - 3666, DOI: 10.1039/b707840d

Title: Sequential C–F activation and borylation of fluoropyridines via intermediate Rh(I) fluoropyridyl complexes: a multinuclear NMR investigation

Authors: Richard J. Lindup, Todd B. Marder, Robin N. Perutz and Adrian C. Whitwood

Abstract: The C–F bond activation of fluoropyridines by [Rh(SiPh3)(PMe3)3] afforded Rh(I) fluoropyridyl complexes of the type [Rh(ArF)(PMe3)3] with concomitant formation of fluorotriphenylsilane; subsequent treatment with bis-catecholatodiboron yielded fac-[Rh(Bcat)3(PMe3)3] and the free fluoropyridyl boronate esters (ArFBcat).


Dalton Trans., 2007, 3914 - 3923, DOI: 10.1039/b708469b

Title: Sn-centred icosahedral Rh carbonyl clusters: synthesis and structural characterization and 13C–{103Rh} HMQC NMR studies

Authors: Cristina Femoni, Maria Carmela Iapalucci, Giuliano Longoni, Cristina Tiozzo, Stefano Zacchini, Brian T. Heaton and Jonathan A. Iggo

Abstract: The reaction of [Rh7(CO)16]3– with SnCl2·2H2O in a 1 : 1 molar ratio under N2 results in the formation of the new heterometallic cluster, [Rh12Sn(CO)27]4–, in very high yield (ca. 86%). Further controlled additions of SnCl2·2H2O, or solutions of HCl, or [RhCl(COD)]2, give [Rh12(µ-Cl)2Sn(CO)23]4–. Similarly, addition of HBr to [Rh12Sn(CO)27]4– gives the related cluster [Rh12(µ-Br)2Sn(CO)23]4–. Notably, if the addition of SnCl2·2H2O to [Rh12Sn(CO)27]4– is carried out under a CO atmosphere, the reaction takes a different course and leads to the formation of the new cluster, [Rh12Sn(µ3-RhCl)(CO)27]4–. All the above clusters have been shown by single-crystal X-ray diffraction studies to have a metal framework based on an icosahedron, which is centred by the unique Sn atom. Their chemical reactivity and 13C–{103Rh} HMQC NMR spectroscopic characterization are also reported.


Dalton Trans., 2007, 4523 - 4528, DOI: 10.1039/b709673a

Title: Ionothermal synthesis, crystal structure and solid-state NMR spectroscopy of a new organically templated gallium oxalatophosphate: (H2TMPD)0.5[Ga3(C2O4)0.5(PO4)3] (TMPD = N,N,N,N-tetramethyl-1,3-propanediamine)

Authors: Ming-Feng Tang, Yi-Hui Liu, Pai-Ching Chang, Yi-Chen Liao, Hsien-Ming Kao and Kwang-Hwa Lii

Abstract: A new organically templated gallium oxalatophosphate, (C7H20N2)0.5[Ga3(C2O4)0.5(PO4)3], has been synthesized by using a low-melting-point eutectic mixture of choline chloride and oxalic acid as a solvent and characterized by single-crystal X-ray diffraction, thermogravimetric analysis and solid-state NMR spectroscopy. It is the first example of ionothermal synthesis of organically templated metal oxalatophosphate. The structure contains double 6-ring units of the composition Ga6(PO4)6 which are connected by oxalate ligands and P–O–Ga bonds to form a 3-D framework. The charge-compensating organic ammonium cations which are disordered over two positions are located at the intersections of two types of 8-ring channels. 1H MAS and 13C CPMAS NMR studies confirm the presence of N,N,N,N-tetramethyl-1,3-propanediammonium cation. The 71Ga and 31P MAS NMR spectra are also consistent with the crystal structure analysis results.


Dalton Trans., 2008, 481 - 490, DOI: 10.1039/b712011g

Title: A solid-state NMR investigation of single-source precursors for group 12 metal selenides; M[N(iPr2PSe)2]2 (M = Zn, Cd, Hg)

Authors: Bryan A. Demko and Roderick E. Wasylishen

Abstract: The first solid-state NMR investigation of dichalcogenoimidodiphosphinato complexes, M[N(R2PE)2]n, is presented. The single-source precursors for metal-selenide materials, M[N(iPr2PSe)2]2 (M = Zn, Cd, Hg), were studied by solid-state 31P, 77Se, 113Cd, and 199Hg NMR at 4.7, 7.0, and 11.7 T, representing the only 77Se NMR measurements, and in the case of Cd[N(iPr2PSe)2]2113Cd NMR measurements, to have been performed on these complexes. Residual dipolar coupling between 14N and 31P was observed in solid-state 31P NMR spectra at 4.7 and 7.0 T yielding average values of R(31P,14N)eff = 880 Hz, CQ(14N) = 3.0 MHz, 1J(31P,14N)iso = 15 Hz, alpha =90°, beta = 26°. The solid-state NMR spectra obtained were used to determine the respective phosphorus, selenium, cadmium, and mercury chemical shift tensors along with the indirect spin–spin coupling constants: 1J(77Se,31P)iso, 1J(111/113Cd,77Se)iso, 1J(199Hg,77Se)iso, and 2J(199Hg,31P)iso. Density functional theory magnetic shielding tensor calculations were performed yielding the orientations of the corresponding chemical shift tensors. For this series of complexes the phosphorus magnetic shielding tensors are essentially identical, the selenium magnetic shielding tensors are also very similar with respect to each other, and the magnetic shielding tensors of the central metals, cadmium and mercury, display near axial symmetry demonstrating an expected deviation from local S4 symmetry.


J. Mater. Chem., 2007, 17, 3167 - 3174, DOI: 10.1039/b702745a

Title: NMR, PDF and RMC study of the positive electrode material Li(Ni0.5Mn0.5)O2 synthesized by ion-exchange methods

Authors: Julien Bréger, Kisuk Kang, Jordi Cabana, Gerbrand Ceder and Clare P. Grey

Abstract: The local environment and short-range ordering of Li(Ni0.5Mn0.5)O2, a potential Li-ion battery positive electrode material obtained via an ion-exchange route from Na(Ni0.5Mn0.5)O2, were investigated by using a combination of 6Li Magic Angle Spinning (MAS) NMR spectroscopy and neutron Pair Distribution Function (PDF) analysis, associated with Reverse Monte Carlo (RMC) calculations. 6Li MAS NMR experiments on Li(Ni0.5Mn0.5)O2 showed that there are almost no Li ions in the transition metal layers. Neutron diffraction data for the precursor Na(Ni0.5Mn0.5)O2 indicated that there is no Na/Ni disorder and that the material is perfectly layered. Neutron PDF analysis of Li(Ni0.5Mn0.5)O2 and Na(Ni0.5Mn0.5)O2 revealed differences in the local transition metal arrangements between those present in the ion-exchanged material and its precursor, and those found in the cathode material synthesized directly from hydroxide starting materials. Large clusters of 3456 atoms were built to investigate cation ordering. Reverse Monte Carlo results, for both the Na and Li-containing compounds, showed a non-random distribution of Ni and Mn cations in the transition metal layers: in the first coordination shell, Ni atoms are on average close to more Mn ions than predicted based on a random distribution of these ions in the transition metal layers. Analysis of the number of Ni/Ni, Mn/Mn and Ni/Mn pairs in the second coordination shell revealed that the Ni and Mn cations show a clear preference for ordering in zigzags rather than in chains.


J. Mater. Chem., 2007, 17, 4316 - 4319, DOI: 10.1039/b707446h

Title: NMR studies of short and intermediate range ordering of amorphous Si–B–N–C–H pre-ceramic at the pyrolysis stage of 600 °C

Authors: Yee Hwa Sehlleier, Aswin Verhoeven and Martin Jansen

Abstract: Inorganic random networks of a pre-ceramic stage of the amorphous ceramic SiBN3C, derived from the single-source precursor Cl3Si(NH)BCl2 (TADB), have been synthesized with isotope-labeled materials. This allowed characterization at an atomic level of the development of the pre-ceramic polymer at a crucial pyrolysis stage of 600 °C by solid-state NMR. Using several techniques including 13C{15N}REDOR, 11B{13C}REDOR, 11B{15N}REDOR and 13C-2D-RFDR, the atomic network of the 13C, 15N enriched sample was investigated. These combined experiments have lead to the important result that carbon forms unsaturated bonds at this stage of the pyrolysis but remains bonded to nitrogen, maintaining a homogeneous distribution of the elements. Carbon atoms seem to be incorporated into the network by using nitrogen atoms as bridges, similar to boron and silicon. The coordinations of boron and silicon are quite similar to those in the final ceramic SiBN3C after pyrolysis at 1400 °C.


J. Mater. Chem., 2007, 17, 5090 - 5096, DOI: 10.1039/b712922j

Title: A multinuclear MAS NMR study of calcium-containing aluminosilicate inorganic polymers

Authors: Kenneth J. D. MacKenzie, Mark E. Smith and Alan Wong

Abstract: Natural abundance 43Ca, 27Al and 29Si MAS NMR spectra were acquired for a series of aluminosilicate inorganic polymers (geopolymers) containing up to 50 wt% of Ca(OH)2, CaCO3, Ca3(PO4)2 and both amorphous and crystalline CaSiO3. The 27Al and 29Si MAS NMR spectra of these geopolymers were generally consistent with those of conventional materials, with their XRD diffractograms showing the presence of the added crystalline phases. Comparison of the 43Ca MAS NMR spectra with those of the calcium starting materials suggests that both the calcium silicates and Ca(OH)2 enter into the geopolymer network, but the spectra of geopolymers containing CaCO3 and Ca3(PO4)2 are identical to those of the original compound, suggesting that the role of these materials is simply as a filler. At the highest concentration of CaCO3, the 43Ca resonance of the aragonite polymorph appears in the geopolymer but disappears on heating at 400 °C for 36 h, suggesting that this is a metastable phase formed in situ under the highly alkaline conditions of geopolymer formation and in the presence of calcite nuclei.


J. Mater. Chem., 2008, 18, 392 - 399, DOI: 10.1039/b714785f

Title: Organosilicas based on purine–pyrimidine base pair assemblies: a solid state NMR point of view

Authors: Guilhem Arrachart, Carole Carcel, Joël J. E. Moreau, Geoffrey Hartmeyer, Bruno Alonso, Dominique Massiot, Gaëlle Creff, Jean-Louis Bantignies, Philippe Dieudonne, Michel Wong Chi Man, Gerhard Althoff, Florence Babonneau and Christian Bonhomme

Abstract: Organosilicas based on adenine (A) and thymine (T) assemblies have been synthesized. A surfactant-free route, based on specific molecular recognition between A and T entities, has been developed. The characterization of the H-bond networks, in both homo- and hetero-assemblies, has been emphasized by using 1H solid state NMR (nuclear magnetic resonance). The latest experimental developments were implemented (i.e. very fast MAS (magic angle spinning) experiments at 750 MHz and 33 kHz), in order to enhance drastically the spectral resolution. Moreover, 1H experiments at 67 kHz in 1.3 mm rotors were performed. Spatial connectivities between protons were established by using 1H–1H DQ (double quantum) MAS experiments, allowing the precise characterization of A/A, T/T and A/T associations.


Chemical Physics Letters

Vol: 443, Issue: 4-6, August 6, 2007

pp. 269-273

Title: Some aspects of spin-locking effect in nitrogen-14 quadrupolar spin-system

Author: Rudakov, T.N.

Abstract (English): It was shown that the modified multi-pulse technique enable the observation of a long train of the spin-echo signals.

Publisher: Elsevier Science


Chemical Physics Letters

Vol: 445, Issue: 1-3, September 4, 2007

pp. 1-5

Title: Proton-detected nitrogen-14 NMR by recoupling of heteronuclear dipolar interactions using symmetry-based sequences

Authors: Cavadini, S.; Abraham, A.; Bodenhausen, G.

Abstract (English): This Letter describes a combination of the heteronuclear multiple-quantum correlation (HMQC) experiment and the symmetry-based R205^9 sequence for the indirect observation of 14N single- (SQ) and double-quantum (DQ) coherences in solids, by recoupling the heteronuclear dipolar interaction between 14N and 1H. The picture shows the N-acetylglycine[D5] experimental spectrum (blue) showing the 14N SQ response of a rigid 14N-1H pair. The quadrupolar parameters obtained with simulation (magenta) are CQ=-3.21MHz and ηQ=0.32.


Chemical Physics Letters

Vol: 445, Issue: 4-6, September 13, 2007

pp. 95-98

Title: The nuclear electric quadrupole moment of lutetium from the molecular method

Authors: Haiduke, R.L.A.; da Silva, A.B.F.; Visscher, L.

Abstract (English):
The nuclear quadrupole moments of lutetium were determined from calculated electric field gradients and experimental nuclear quadrupole coupling constants.

Elsevier Science


Chemical Physics Letters

Vol: 447, Issue: 1-3, October 15, 2007

pp. 154-161

Title: Optimal control based design of composite dipolar recoupling experiments by analogy to single-spin inversion pulses

Authors: Hansen, J.O.; Kehlet, C.; Bjerring, M.; Vosegaard, T.; Glaser, S.J.; Khaneja, N.; Nielsen, N.Chr.

Abstract (English): Solid-state NMR composite dipolar recoupling experiments designed from a single-spin pulse analogy using optimal control based numerical optimization.

Publisher: Elsevier Science


Chemical Physics Letters

Vol: 447, Issue: 4-6, October 25, 2007

pp. 370-374

Title: A broad-banded z-rotation windowed phase-modulated Lee-Goldburg pulse sequence for 1H spectroscopy in solid-state NMR

Authors: Leskes, M.; Madhu, P.K.; Vega, S.

Abstract (English): The design and experimental implementation of an effective z-rotation wPMLG sequence for 1H spectroscopy in solid-state NMR is demonstrated with a scale factor independent of radio-frequency imperfections.

Publisher: Elsevier Science


Chemical Physics Letters

Vol: 449, Issue: 1-3, November 26, 2007

pp. 86-91

Title: Effects of spin diffusion on spin-lattice relaxation in solid-state 2H MAS NMR spectroscopy

Authors: Cutajar, M.; Lewis, M.H.; Wimperis, S.

Abstract (English): The phenomenon of MAS-enhanced spin diffusion can lead to observation of a common spin-lattice (T1) relaxation time in 2H NMR.


Chemical Physics Letters

Vol: 450, Issue: 4-6, January 4, 2008

pp. 417-421

Title: Sensitivity enhancement of solid-state NMR spectra of half-integer spin quadrupolar nuclei: Double- or single-frequency sweeps? Insights from the hyperbolic secant experiment

Authors: Nakashima, T.T.; Wasylishen, R.E.; Siegel, R.; Ooms, K.J.

Abstract (English): Enhancement of the central NMR transition of quadrupolar nuclei in solids by selective irradiation of one ssb in MAS experiments.

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