@article {1399,
	title = {Determination of the location of naphthalene in the zeolite ZSM-5 host framework by solid-state H-1/Si-29 CP MAS NMR spectroscopy},
	journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie},
	volume = {84},
	number = {2},
	year = {2006},
	note = {ISI Document Delivery No.: 040YKTimes Cited: 3Cited Reference Count: 23},
	month = {Feb},
	pages = {345-355},
	type = {Article},
	abstract = {The location of naphthalene in the zeolite ZSM-5 has been determined from solid-state H-1/Si-29 cross-polarization (CP) magic-angle-spinning (MAS) NMR data alone. With the peaks in the Si-29 spectrum assigned to the inequivalent Si sites in the zeolite from a two-dimensional INADEQUATE spectrum, the rates of cross polarization between the H-1 nuclei of the guest sorbate molecules and the Si-29 nuclei of the zeolite framework were used to determine the location of the naphthalene molecules by exploiting the proportional relationship between cross-polarization rate constants and H-1/Si-29 dipolar coupling second moments. The NMR structure determination was carried out on three different selectively deuterium-labeled naphthalene molecules (naphthalene-d(0), alpha-naphthalene-d(4), and beta-naphthalene-d(4)). The average of the molecule locations in agreement with all three sets of NMR data was found to be in excellent agreement with an existing single crystal XRD structure of the naphthalene-ZSM-5 complex.},
	keywords = {COMPLEXES, cross polarization, CROSS-POLARIZATION, host-guest complexes, RAY-POWDER DIFFRACTION, SOLID-STATE NMR, SORBATE, SPECTRA, structure determination, zeolites},
	isbn = {0008-4042},
	url = {<Go to ISI>://000237417600033},
	author = {Fyfe, C. A. and Brouwer, D. H.}
}
@article {1398,
	title = {Optimization, standardization, and testing of a new NMR method for the determination of zeolite host-organic guest crystal structures},
	journal = {Journal of the American Chemical Society},
	volume = {128},
	number = {36},
	year = {2006},
	note = {ISI Document Delivery No.: 081BJTimes Cited: 15Cited Reference Count: 42Fyfe, Colin A. Brouwer, Darren H.},
	month = {Sep},
	pages = {11860-11871},
	type = {Article},
	abstract = {An optimized and automated protocol for determining the location of guest sorbate molecules in highly siliceous zeolites from Si-29 INADEQUATE and H-1/Si-29 cross polarization (CP) magic-angle spinning (MAS) NMR experiments is described. With the peaks in the Si-29 MAS NMR spectrum assigned to the unique Si sites in the zeolite framework by a 2D(29)Si INADEQUATE experiment, the location of the sorbate molecule is found by systematically searching for sorbate locations for which the measured rates of H-1/Si-29 cross polarization of the different Si sites correlate linearly with H-1/Si-29 second moments calculated from H-Si distances. Due to the H-1/Si-29 cross polarization being in the "slow CP regime" for many zeolite-sorbate complexes, it is proposed that the CP rate constants are best measured by H-1/Si-29 cross polarization drain experiments, if possible, to avoid complications that may arise from fast H-1 and Si-29 T-1 rho relaxations. An algorithm for determining the sorbate molecule location is described in detail. A number of ways to effectively summarize and display the large number of solutions which typically result from a prediction of the structure from the CP MAS NMR data are presented, including estimates of the errors involved in the structure determinations. As a working example throughout this paper, the structure of the low loaded rho-dichlorobenzene/ZSM-5 complex is determined under different conditions from solid-state H-1/Si-29 CP MAS NMR data, and the solutions are shown to be in excellent agreement with the known single-crystal X-ray diffraction structure. This structure determination approach is shown to be quite insensitive to the use of relative rate constants rather than absolute values, to the detailed structure of the zeolite framework, and relatively insensitive to temperature and motions.},
	keywords = {2ND MOMENT, CROSS-POLARIZATION, DETERMINATIONS, DISTANCE, H-ZSM-5, P-DICHLOROBENZENE, SINGLE-CRYSTAL, SOLID-STATE, SORBATE, SPINNING NMR, ZSM-5},
	isbn = {0002-7863},
	url = {<Go to ISI>://000240291900035},
	author = {Fyfe, C. A. and Brouwer, D. H.}
}
@article {1115,
	title = {Solid state NMR method for the determination of 3D zeolite framework/sorbate structures: H-1/Si-29 CP MAS NMR study of the high-loaded form of p-xylene in ZSM-5 and determination of the unknown structure of the low-loaded form},
	journal = {Journal of the American Chemical Society},
	volume = {127},
	number = {20},
	year = {2005},
	note = {ISI Document Delivery No.: 928AXTimes Cited: 22Cited Reference Count: 57},
	month = {May},
	pages = {7543-7558},
	type = {Article},
	abstract = {A general protocol is described for structure determinations of organic sorbate-zeolite complexes based on the selective, through-space, distance-dependent transfer of magnetization from protons in selectively deuterated organics to framework silicon nuclei. The method was developed using the known structure of the high-loaded ZSM-5/p-xylene complex containing p-xylene-d(6) or p-xylene-d(4). It was then applied to determine the unknown structure of the low-loaded ZSM-5/p-xylene complex using NMR alone. For the high-loaded complex improved data were obtained below 273 K, where slow motions and exchange processes of the p-xylene are eliminated. The general approach was validated by. the exact agreement of the experimental H-1-Si-29 CPMAS spectra obtained at a specific contact time and the complete 24-line spectra simulated using 1/T-CP vs M-2 correlations from only the six clearly resolved resonances. For the low-loaded complex the Si-29 resonances were assigned at 267 K, and variable contact time CP experiments were carried out between 243 and 173 K using the same specifically deuterated p-xylenes. All possible locations and orientations of the p-xylene guests were sampled, and those solutions that gave acceptable linear 1/T-CP vs M-2 correlations were selected. The optimum p-xylene location in this temperature range was determined to be in the channel intersection with the long molecular axis parallel to [0,1,0] (ring center fractional coordinates {-0.009, 0.250, 0.541}) with the ring plane oriented at an angle of 30 +/- 3 degrees about the crystallographic b axis. A subsequent single-crystal X-ray study confirmed this predicted structure.},
	keywords = {3-DIMENSIONAL BONDING CONNECTIVITIES, CROSS-POLARIZATION, CRYSTAL STRUCTURE-ANALYSIS, LATTICE, MAGIC-ANGLE, NATURAL-ABUNDANCE, NUCLEAR-MAGNETIC-RESONANCE, PROTON-ENHANCED NMR, SINGLE-CRYSTAL, SPINNING NMR, structures},
	isbn = {0002-7863},
	url = {<Go to ISI>://000229244600061},
	author = {Fyfe, C. A. and Diaz, A. C. and Grondey, H. and Lewis, A. R. and Forster, H.}
}
@article {993,
	title = {Recent developments in solid-state magic-angle spinning, nuclear magnetic resonance of fully and significantly isotopically labelled peptides and proteins},
	journal = {Philosophical Transactions of the Royal Society of London Series B-Biological Sciences},
	volume = {359},
	number = {1446},
	year = {2004},
	note = {ISI Document Delivery No.: 834XSTimes Cited: 7Cited Reference Count: 125},
	month = {Jun},
	pages = {997-1008},
	type = {Review},
	abstract = {In recent years, a large number of solid-state nuclear magnetic resonance (NMR) techniques have been developed and applied to the study of fully or significantly isotopically labelled (C-13, N-15 or C-13/N-15) biomolecules. In the past few years, the first structures of C-13/N-15-labelled peptides, Gly-Ile and Met-Leu-Phe, and a protein, Src-homology 3 domain, were solved using magic-angle spinning NMR, without recourse to any structural information obtained from other methods. This progress has been made possible by the development of NMR experiments to assign solid-state spectra and experiments to extract distance and orientational information. Another key aspect to the success of solid-state NMR is the advances made in sample preparation. These improvements will be reviewed in this contribution. Future prospects for the application of solid-state NMR to interesting biological questions will also briefly be discussed.},
	keywords = {assignment strategies, CHEMICAL-SHIFT ANISOTROPIES, CROSS-POLARIZATION, DIPOLAR-CORRELATION SPECTROSCOPY, DISTANCE, HIGH-FIELD, magic-angle spinning, MAS NMR, MEASUREMENTS, MEMBRANE-PROTEIN, NMR-SPECTROSCOPY, peptide and protein labelling, RESOLUTION, ROTATING SOLIDS, SH3 DOMAIN, SOLID-STATE NMR, SPECTRIN, structural parameters},
	isbn = {0962-8436},
	url = {<Go to ISI>://000222444800010},
	author = {Straus, S. K.}
}
@article {625,
	title = {The amblygonite (LiAlPO4F)-montebrasite (LiAlPO4OH) solid solution: A combined powder and single-crystal neutron diffraction and solid-state Li-6 MAS, CP MAS, and REDOR NMR study},
	journal = {American Mineralogist},
	volume = {88},
	number = {1},
	year = {2003},
	note = {ISI Document Delivery No.: 635DVTimes Cited: 10Cited Reference Count: 29},
	month = {Jan},
	pages = {195-210},
	type = {Article},
	abstract = {The amblygonite-montebrasite series of minerals, common constituents of granitic pegmatites and topaz-bearing granites, show complete solid solution with ideal composition LiAlPO4(F, OH). These compounds are ideal for studying F <{\textendash}{\textendash}> OH solid solution in minerals because natural members of the series generally show little deviation from the ideal composition. In this study, we used powder and single-crystal neutron diffraction and solid-state Li-6 MAS, CP MAS, and REDOR NMR techniques to study the effect of F <{\textendash}{\textendash}> OH substitution on the series. Lattice parameters refined from single-crystal neutron diffraction data show increasing b and decreasing a, c, and V with increasing F/(F + OH). The volume is highest for the OH end-member because of the presence of an additional atom (H). The a and c parameters decrease with increasing F/(F + OH) because the O-H vector is close to the a-c plane and the Al-OH/F vectors are approximately parallel to c. Lattice parameters refined from neutron powder diffraction patterns collected at lower T show that thermal contraction increases with F/(F + OH), presumably because the F anion takes up less space than the OH molecule. The results show that the OH/F position is always fully occupied. The H displacement ellipsoid shows little change with occupancy, which obviously corresponds negatively with increasing F/(F + OH). However, the Li displacement ellipsoid becomes extremely large and anisotropic with increasing F fraction. Most of the distortion is associated with the U-3 eigenvalue, which lies between the c and c* directions. U-eq values corresponding to the Li atom show a greater reduction with decreasing temperature than the other atoms. The temperature dependence of Li is the same regardless of F content. Even when extrapolated to absolute zero the Li displacement ellipsoid is very large, which implies a large static disorder. At the montebrasite end of the series, there are five short Li-phi (phi = O, OH, F) distances and one very long Li-O4 bond. With increasing F content, the Li-O4 distance decreases and the Li-O3f distance increases, such that at the amblygonite end, the coordination is 4 + 2. The disorder in the Li site is obviously caused by the substitution of F for OH. The driving force is the loss of the hydrogen bond to 04, which causes the Li-O4 bond to strengthen and improves the bond valence to O4. The results show that the H atom position is imbedded within the distorted octahedral oxygen coordination of the Li atom. To represent the disorder better, we used a split Li site model. The results show that Li1 occupancy increases and the Li2 occupancy decreases with increasing F content, and that the Li1-Li2 distance is longer for intermediate compositions than for the end-members. The Li-6 MAS NMR experiments provide important structural information complementary to the neutron diffraction results. The spectra of samples in the amblygonite-montebrasite series show two well-resolved peaks, confirming the presence of Li disorder over two distinct sites, and highly resolved Li-6 MAS NMR spectra are obtained at the very high magnetic field strength of 18.8 T. The peaks at -0.3 ppm and -0.9 ppm were unambiguously assigned to the Li2(OH) and Li1(F) sites found in the neutron diffraction structures. The isotropic chemical shifts are consistent with the coordinations of these Li sites found in the neutron diffraction structures. The relative intensities of the two peaks across the series of samples reflect the varying F/(F + OH). In addition to confirming the assignments of the peaks, it is possible to measure H-Li2 and F-Li1 internuclear distances by Li-6 {H-1} and Li-6 {F-19} CP and REDOR NMR that are consistent with the corresponding distances from the neutron diffraction structures. The Li-6 {H-1} and Li-6 {F-19} CP and REDOR results indicate that the Li disorder is random throughout the crystals rather than over large domains, a conclusion that cannot be made from diffraction experiments. Variable temperature Li-6 MAS NMR spectra confirm that the disorder is static and there is no dynamic exchange involving F, OH, or Li. Each Li ion has access to only one of the two observed sites as determined by the presence of either OH or F in its immediate environment and there is no possibility of a dynamic exchange.},
	keywords = {CROSS-POLARIZATION, DISTANCE DETERMINATIONS, FLUORINE},
	isbn = {0003-004X},
	url = {<Go to ISI>://000180383600023},
	author = {Groat, L. A. and Chakoumakos, B. C. and Brouwer, D. H. and Hoffman, C. M. and Fyfe, C. A. and Morell, H. and Schultz, A. J.}
}
@article {382,
	title = {Combined solid state NMR and X-ray diffraction investigation of the local structure of the five-coordinate silicon in fluoride-containing as-synthesized STF zeolite},
	journal = {Journal of the American Chemical Society},
	volume = {124},
	number = {26},
	year = {2002},
	note = {ISI Document Delivery No.: 567YYTimes Cited: 41Cited Reference Count: 48},
	month = {Jul},
	pages = {7770-7778},
	type = {Article},
	abstract = {The local structure of the [SiO4/2F](-) unit in fluoride-containing as-synthesized STF zeolite has been experimentally determined by a combination of solid-state NMR and microcrystal X-ray diffraction to be very close to trigonal bipyramidal. Because the fluoride ions are disordered over two sites, the resulting local structure of the [SiO4/2F](-) unit from a conventional XRD refinement is an average between tetrahedral SiO4/2 and five-coordinate [SiO4/2F](-), giving an apparent F-Si distance longer than expected. The correct F-Si distance was determined by slow spinning MAS and fast spinning F-19/Si-29 CP and REDOR solid-state NMR experiments and found to be between 1.72 and 1.79 Angstrom. In light of this, the X-ray structure was re-refined, including the disorder at Si3. The resulting local structure of the [SiO4/2F]- unit was very close to trigonal bipyramidal with a F-Si distance of 1.744 (6) Angstrom, in agreement with the NMR results and the prediction of Density Functional Theory calculations. In addition, further evidence for the existence of a covalent F-Si bond is provided by a F-19{\textendash}>Si-29 refocused INEPT experiment. The resonance for the five-coordinate species at -147.5 ppm in the Si-29 Spectrum is a doublet due to the F-19/Si-29 J-coupling of 165 Hz. The peaks in this doublet have remarkably different effective chemical shift anisotropies due to the interplay of the CSA, dipolar coupling, and J-coupling tensors. The distortions from tetrahedral geometry of the neighboring silicon atoms to the five-coordinate Si3 atom are manifested in increased delta(aniso) values. This information, along with F-Si distances measured by F-19{\textendash}>Si-29 CP experiments, makes it possible to assign half of the Si-29 resonances to unique tetrahedral sites. As well as determining the local geometry of the [SiO4/2F](-) unit, the work presented here demonstrates the complementarity of the solid-state NMR and X-ray diffraction techniques and the advantages of using them together.},
	keywords = {5-COORDINATE SILICON, C-13 NMR, CONTAINING OCTADECASIL, CROSS-POLARIZATION, DISTANCE DETERMINATIONS, LOCATION, MOLECULAR-SIEVES, P-31 NMR, POLARIZATION TRANSFER, PROTON-ENHANCED NMR},
	isbn = {0002-7863},
	url = {<Go to ISI>://000176516400032},
	author = {Fyfe, C. A. and Brouwer, D. H. and Lewis, A. R. and Villaescusa, L. A. and Morris, R. E.}
}
@article {3979,
	title = {F-19/Si-29 distance determinations in fluoride-containing octadecasil from solid-state NMR measurements},
	journal = {Journal of the American Chemical Society},
	volume = {119},
	number = {50},
	year = {1997},
	note = {ISI Document Delivery No.: YN229Times Cited: 48Cited Reference Count: 76},
	month = {Dec},
	pages = {12210-12222},
	type = {Article},
	abstract = {In the present work we report results from CP, REDOR, and TEDOR NMR experiments carried out to locate the fluoride anions within the three-dimensional framework of the silicate octadecasil. Accurate Si-F distances were obtained-through measurements of the F-19/Si-29 dipolar couplings from these experiments. Weighted, nonlinear least-squares fittings of the REDOR and TEDOR data for the silicons in the D4R units gave an average value of D = 1150 +/- 50 Hz from which the Si-F interatomic distance was calculated to be 2.69 +/- 0.04 Angstrom. This distance is in excellent agreement with the value of 2.63 Angstrom reported from the X-ray determined single crystal structure-and confirms that the F- anions are located inside the D4R units. Calculations and fittings of the REDOR and TEDOR data for the silicons not in the D4R gave = 120 +/- 20 Hz when the specific geometrical (tetrahedral) arrangement of the multiple equivalent fluoride anions surrounding the Si nuclei in these T-2 sites was taken into account. This yields a Si-F distance of 5.7 +/- 0.4 Angstrom, compared to the value 5.69 Angstrom obtained from the diffraction measurements. Factors influencing the selection of the optimum experiments to perform in different situations and the dependence of the results on experimental variables are discussed. These studies clearly establish the viability and reliability of F-19/Si-29 REDOR and TEDOR NMR experiments to obtain distance information which can be used to determine the precise location of fluorine-containing species within such framework structures or in suitable cases to assist in the determination of the framework structure itself where it is unknown.},
	keywords = {3-DIMENSIONAL LATTICE CONNECTIVITIES, CROSS-POLARIZATION, CRYSTAL-STRUCTURE, DOUBLE-RESONANCE NMR, INTERATOMIC DISTANCE, MICROPOROUS, MOLECULAR-SIEVE, P-DICHLOROBENZENE, ROTATIONAL-ECHO, SINGLE-CRYSTAL, SOLIDS},
	isbn = {0002-7863},
	url = {<Go to ISI>://000071146000024},
	author = {Fyfe, C. A. and Lewis, A. R. and Chezeau, J. M. and Grondey, H.}
}
@article {3339,
	title = {DIPOLAR-BASED AL-27-]SI-29 SOLID-STATE NMR CONNECTIVITY EXPERIMENTS IN ZEOLITE MOLECULAR-SIEVE FRAMEWORKS},
	journal = {Journal of Physical Chemistry},
	volume = {99},
	number = {21},
	year = {1995},
	note = {ISI Document Delivery No.: RA147Times Cited: 64Cited Reference Count: 38},
	month = {May},
	pages = {8707-8716},
	type = {Article},
	abstract = {In this work we present the results of a systematic investigation of a set of dipolar-based Al-27 {\textendash}> Si-29 connectivity experiments for a series: of representative zeolite molecular sieve frameworks: zeolites A, X, Y, and Omega. Coherence transfer from quadrupolar Al-27 (I = 5/2) to Si-29 (I = 1/2) nuclei through cross polarization and transferred-echo double-resonance (TEDOR) experiments is. observed, and an experimental investigation of the parameters controlling the efficiency of both experiments is presented. Rotational-echo double-resonance (REDOR) and dipolar-dephasing difference experiments are also demonstrated. These experiments utilize the heteronuclear dipolar couplings, whose magnitudes are proportional to the inverse third power of the internuclear distance and are therefore extremely sensitive to the separation of the coupled spins. In addition, we demonstrate that for these dipolar-based experiments, there is a relative enhancement of a given resonance which is approximately linear with the number of aluminum atoms in the neighboring tetrahedral sites. Two-dimensional extensions of the cross-polarization and TEDOR experiments are also possible and will be of use for complex mixtures or where several resonances are observable in the one-dimensional spectra of the two nuclei.},
	keywords = {ANGLE, CROSS-POLARIZATION, DOUBLE-ROTOR, ECHO DOUBLE-RESONANCE, INORGANIC SOLIDS, MAS-NMR, NMR, NUCLEAR MAGNETIC-RESONANCE, QUADRUPOLAR NUCLEI, SPECTROSCOPY, VPI-5},
	isbn = {0022-3654},
	url = {<Go to ISI>://A1995RA14700041},
	author = {Fyfe, C. A. and Wongmoon, K. C. and Huang, Y. and Grondey, H. and Mueller, K. T.}
}
@article {7242,
	title = {AN ALTERNATIVE PREPARATION OF ORGANOFUNCTIONALIZED SILICA-GELS AND THEIR CHARACTERIZATION BY 2-DIMENSIONAL HIGH-RESOLUTION SOLID-STATE HETERONUCLEAR NMR CORRELATION SPECTROSCOPY},
	journal = {Journal of the American Chemical Society},
	volume = {114},
	number = {9},
	year = {1992},
	note = {ISI Document Delivery No.: HQ814Times Cited: 70Cited Reference Count: 11},
	month = {Apr},
	pages = {3252-3255},
	type = {Article},
	abstract = {High-resolution solid-state Si-29 CP/MAS NMR spectroscopy has been used to characterize methyl functionalized silica gels prepared by the copolymerization of tetraethoxysilane and methyltriethoxysilane. One-dimensional Si-29 CP/MAS NMR indicates that the two components are present in the correct proportions in the gel, but it is not sensitive to the degree of mixing. A two-dimensional H-1/Si-29 correlation experiment clearly demonstrates that the two components are not phase-separated, but are mixed in the final gel.},
	keywords = {CROSS-POLARIZATION, NUCLEAR MAGNETIC-RESONANCE, SURFACE},
	isbn = {0002-7863},
	url = {<Go to ISI>://A1992HQ81400014},
	author = {Fyfe, C. A. and Zhang, Y. and Aroca, P.}
}
