@article {4815,
	title = {Investigation of the viability of solid-state NMR distance determinations in multiple spin systems of unknown structure},
	journal = {Journal of Physical Chemistry B},
	volume = {104},
	number = {1},
	year = {2000},
	note = {ISI Document Delivery No.: 283BJTimes Cited: 26Cited Reference Count: 37},
	month = {Jan},
	pages = {48-55},
	type = {Article},
	abstract = {This paper presents theoretical rotational-echo double-resonance (REDOR) and transferred-echo double-resonance (TEDOR) curves calculated for several three-spin systems and explores the potential for determining reliable distances in multiple-spin systems of unknown geometry. These NMR techniques can provide distances which compare very well with those obtained by X-ray diffraction if the samples contain isolated heteronuclear (IS) spin pairs and are currently being used in structural investigations of solids including peptides, polymers, and inorganic materials. The situation is less clear when small clusters of spins (e.g., INS systems) are present, and although the multispin dephasing can be calculated, very few examples have been reported in the literature. In most cases the spin system geometry was known before analysis of the NMR data, thus it is unclear whether reliable distances can be determined when the geometry of the spin system is completely unknown. To investigate the uniqueness of distance determinations from fitting of multispin REDOR and TEDOR data, the theoretical dephasing was calculated for a selection of I2S systems. The effects of varying the two I-S dipolar couplings and the I-A-S-I-B angle, zeta, were studied. The full range of zeta (0 degrees less than or equal to zeta less than or equal to 180 degrees) was considered, and the magnitudes of the dipolar couplings selected are typical of couplings expected for commonly studied nuclei. A variation of 10 degrees or more is required to effect a noticeable change and the dephasing is identical for zeta and 180 degrees - zeta. The most distinctive behavior is observed when zeta is small (or close to 180 degrees), otherwise there are quite minor differences. Spin systems with quite different geometries may exhibit very similar dephasing, and in some cases the curves are identical to those for an isolated IS spin pair. These calculations indicate that it is highly unlikely that reliable distances can be obtained directly from REDOR and TEDOR experiments on multiple spin systems when the number of spins and their geometrical arrangement is completely unknown. Furthermore, it is possible to obtain incorrect distances if isolated spin pairs are assumed and multiple spins are present.},
	keywords = {COMPLEX, DOUBLE-RESONANCE NMR, ECHO DOUBLE-RESONANCE, NMR, NUCLEI, QUADRUPOLAR, REDOR, ROTATIONAL-ECHO, zeolites},
	isbn = {1089-5647},
	url = {<Go to ISI>://000085256000007},
	author = {Fyfe, C. A. and Lewis, A. R.}
}
@article {3976,
	title = {1D and 2D solid state NMR investigations of the framework structure of As-synthesized AlPO4-14},
	journal = {Solid State Nuclear Magnetic Resonance},
	volume = {9},
	number = {2-4},
	year = {1997},
	note = {ISI Document Delivery No.: YU021Times Cited: 46Cited Reference Count: 21},
	month = {Dec},
	pages = {97-106},
	type = {Article},
	abstract = {The framework structure of As-synthesized ALPO(4)-14 has been investigated with a combination of different one-dimensional Al-27 and P-31 solid State NMR techniques and Al-27/P-31 double resonance methods. The results are found to be fully consistent with the assumed structural model. Al-27 MAS and DOR experiments at three different magnetic field strengths together with simulations show the presence of two tetrahedral sites, one pentacoordinated and one octahedral aluminum site. The Al-27 quadrupolar coupling constants and the P-31 isotropic chemical shifts of the tetrahedral sites correlate well with tetrahedral shear-strain parameters and mean P-O-Al bond angles, respectively. These correlations allow one to assign all of the NMR resonances to specific T-sites in the proposed framework structure. The assignments are then further confirmed by the application of three different two-dimensional heteronuclear correlation methods (i.e., Al-27 {\textendash}> P-31 TEDOR, CP, and INEPT) which reveal the connectivities between AlOx and PO4 polyhedra. The two-dimensional INEPT experiment is applied here for the first time in the solid state. (C) 1997 Published by Elsevier Science B.V.},
	keywords = {AL-27, Al-27 nuclear magnetic resonance spectroscopy, aluminophosphate, ANGLE, double resonance, MOLECULAR, MOLECULAR-SIEVE VPI-5, NUCLEI, P-31 NMR, P-31 nuclear magnetic, QUADRUPOLAR, RESOLUTION, resonance spectroscopy, sieve, SPIN},
	isbn = {0926-2040},
	url = {<Go to ISI>://000071671900004},
	author = {Fyfe, C. A. and Altenschildesche, H. M. Z. and Wong-Moon, K. C. and Grondey, H. and Chezeau, J. M.}
}
@article {3677,
	title = {Al-27/P-31 solid-state nmr structural investigations of AlPO4-5 molecular sieve},
	journal = {Zeolites},
	volume = {16},
	number = {1},
	year = {1996},
	note = {ISI Document Delivery No.: TM037Times Cited: 26Cited Reference Count: 16},
	month = {Jan},
	pages = {50-55},
	type = {Article},
	abstract = {Al-27/P-31 solid-state n.m.r. connectivity experiments were used to investigate the structure of the molecular sieve AlPO4-5 hydrated with D2O. Hydration with D2O resulted in an increased efficiency of coherence transfer from octahedral Al-27 to P-31 compared with hydration with H2O. The experiments prove directly that both the tetrahedral aluminum and the octahedral aluminum formed upon hydration are connected to phosphorus in the framework. The two-dimensional Al-27 {\textendash}> P-31 transferred-echo double-resonance and cross-polarization experiments show a downfield offset of the octahedral Al-27 correlation from the tetrahedral Al-27 correlation, consistent with the growth of a downfield shoulder on the P-31 resonance as water is incorporated into the lattice.},
	keywords = {Al-27/P-31 solid-state nmr connectivity experiments, AlPO4-5, FRAMEWORK, NMR, NUCLEI, octahedral aluminum, QUADRUPOLAR, VPI-5},
	isbn = {0144-2449},
	url = {<Go to ISI>://A1996TM03700009},
	author = {Fyfe, C. A. and Wongmoon, K. C. and Huang, Y.}
}
@article {3338,
	title = {INEPT EXPERIMENTS IN SOLID-STATE NMR},
	journal = {Journal of the American Chemical Society},
	volume = {117},
	number = {41},
	year = {1995},
	note = {ISI Document Delivery No.: TB353Times Cited: 38Cited Reference Count: 16},
	month = {Oct},
	pages = {10397-10398},
	type = {Note},
	keywords = {DOUBLE-RESONANCE NMR, ENHANCEMENT, HELICAL PEPTIDE, INTERATOMIC DISTANCE, NUCLEI, POLARIZATION TRANSFER, QUADRUPOLAR, REDOR, SIGNALS, VPI-5},
	isbn = {0002-7863},
	url = {<Go to ISI>://A1995TB35300031},
	author = {Fyfe, C. A. and Wongmoon, K. C. and Huang, Y. and Grondey, H.}
}
@article {3337,
	title = {STRUCTURAL INVESTIGATIONS OF SAPO-37 MOLECULAR-SIEVE BY COHERENCE-TRANSFER AND DIPOLAR-DEPHASING SOLID-STATE NUCLEAR-MAGNETIC-RESONANCE EXPERIMENTS},
	journal = {Microporous Materials},
	volume = {5},
	number = {1-2},
	year = {1995},
	note = {ISI Document Delivery No.: TD675Times Cited: 16Cited Reference Count: 21},
	month = {Oct},
	pages = {29-37},
	type = {Article},
	abstract = {In this work, dipolar-based coherence-transfer and dipolar-dephasing solid-state nuclear magnetic resonance (NMR) experiments were performed to investigate the structure of the silicoaluminophosphate molecular sieve SAPO-37. The Al-27,Si-29 transferred-echo double-resonance (TEDOR) experiment directly proves, for the first time, that silicon substitutes for phosphorus atoms in the framework via the SM2 mechanism. The Al-27 (P-31) and Al-27 (Si-29) dipolar-dephasing difference experiments and the two-dimensional Al-27{\textendash}>P-31 TEDOR experiment indicate the presence of three types of aluminum environments: tetrahedral Al surrounded by symmetrical [4P] or [4Si] environments which give rise to a sharp resonance, tetrahedral Al surrounded by asymmetrical [3P, Si], [2P, 2Si] or [P, 3Si] environments which give rise to a broad resonance, and also extra-framework amorphous octahedral Al.},
	keywords = {AL-27, COHERENCE-TRANSFER, DIPOLAR-DEPHASING, NMR, QUADRUPOLAR, SAPO-37 MOLECULAR SIEVE, SILICOALUMINOPHOSPHATE, TRANSFERRED-ECHO DOUBLE-RESONANCE, VPI-5},
	isbn = {0927-6513},
	url = {<Go to ISI>://A1995TD67500004},
	author = {Fyfe, C. A. and Wongmoon, K. C. and Huang, Y. and Grondey, H.}
}
@article {7021,
	title = {ONE-DIMENSIONAL AND 2-DIMENSIONAL HIGH-RESOLUTION SOLID-STATE NMR-STUDIES OF ZEOLITE LATTICE STRUCTURES},
	journal = {Chemical Reviews},
	volume = {91},
	number = {7},
	year = {1991},
	note = {ISI Document Delivery No.: GP764Times Cited: 106Cited Reference Count: 90},
	month = {Nov},
	pages = {1525-1543},
	type = {Review},
	keywords = {C-13 NMR, CRYSTAL-STRUCTURE, CRYSTALLOGRAPHICALLY INEQUIVALENT SITES, HIGH-SILICA ZEOLITE, MAS-NMR, NUCLEAR MAGNETIC-RESONANCE, NUCLEI, ORTHORHOMBIC FRAMEWORK, QUADRUPOLAR, Si-29 NMR, X-RAY-DIFFRACTION},
	isbn = {0009-2665},
	url = {<Go to ISI>://A1991GP76400014},
	author = {Fyfe, C. A. and Feng, Y. and Grondey, H. and Kokotailo, G. T. and Gies, H.}
}
