@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 {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.}
}
