@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 {1114,
	title = {Measurement of NMR cross-polarization (CP) rate constants in the slow CP regime: Relevance to structure determinations of zeolite-sorbate and other complexes by CP magic-angle spinning NMR},
	journal = {Journal of Physical Chemistry A},
	volume = {109},
	number = {28},
	year = {2005},
	note = {ISI Document Delivery No.: 945UBTimes Cited: 8Cited Reference Count: 22},
	month = {Jul},
	pages = {6187-6192},
	type = {Article},
	abstract = {When analyzing I -> S variable contact time cross-polarization (CP) curves, the spin dynamics are usually assumed to be describable in the "fast CP regime" in which the growth of the S spin magnetization is governed by the rate of cross polarization while its decay is governed by the rate of I spin Tip relaxation. However, in the investigation of the structures of zeolite-sorbate and other complexes by polarization transfer this will not necessarily be the case. We discuss the measurement of I -> S CP rate constants under the "slow CP regime" in which the rate of Tip relaxation is fast compared to the rate of cross polarization, leading to a reversal of the usual assumptions such that the rate or growth is governed by the rate of I spin Tip relaxation while the decay is governed by the rate of cross polarization (and the S spin Tip relaxation). It is very important to recognize when a system is in the slow CP regime, as an analysis assuming the normal fast CP will lead to erroneous data. However, even when the slow CP regime is recognized, it is difficult to obtain absolute values for the CP rate constants from fits to standard CP curves, since the CP rate constant is correlated to the scaling factor, the contribution from Si-29 T-1 rho relaxation is ignored, and it is difficult to obtain reliable data at very long contact times. The use of a S-29{H-1} CP "drain" or "depolarization" experiment, which measures absolute values of the CP rate constants, is therefore proposed as being most appropriate for theses situations. To illustrate the importance of these observations, measurements of the H-1-Si-29 CP rate constants in the p-dichlorobenzene/ZSM-5 sorbate-zeolite complex by Si-29{H-1} CP and CP drain magic-angle spinning (MAS) NMR experiments are presented and compared and used to determine the location of the guest sorbate molecules in the cavities of the host zeolite framework.},
	keywords = {DYNAMICS, SILICATE, SOLID-STATE NMR, SPECTRA, ZSM-5},
	isbn = {1089-5639},
	url = {<Go to ISI>://000230526600007},
	author = {Fyfe, C. A. and Brouwer, D. H. and Tekely, P.}
}
@article {856,
	title = {Effect of molecular oxygen on the variable-temperature Si-29 MAS NMR spectra of zeolite-sorbate complexes},
	journal = {Journal of the American Chemical Society},
	volume = {126},
	number = {5},
	year = {2004},
	note = {ISI Document Delivery No.: 772GXTimes Cited: 5Cited Reference Count: 8},
	month = {Feb},
	pages = {1306-1307},
	type = {Article},
	keywords = {SILICALITE, SPIN-LATTICE-RELAXATION, ZSM-5},
	isbn = {0002-7863},
	url = {<Go to ISI>://000188834900003},
	author = {Fyfe, C. A. and Brouwer, D. H.}
}
@article {450,
	title = {Structural investigation of Silicalite-I loaded with n-hexane by X-ray diffraction, Si-29 MAS NMR, and molecular modeling},
	journal = {Chemistry of Materials},
	volume = {14},
	number = {5},
	year = {2002},
	note = {ISI Document Delivery No.: 555JCTimes Cited: 23Cited Reference Count: 25},
	month = {May},
	pages = {2192-2198},
	type = {Article},
	abstract = {{The room temperature (298 K) structure of zeolite Silicalite-I loaded with approximately eight n-hexane molecules per unit cell was solved from twinned single-crystal X-ray diffraction (XRD) data in the monoclinic space group P12(1)/n1 with a = 19.8247(2) Angstrom},
	keywords = {ADSORPTION, ALKANES, ENERGY-MINIMIZATION CALCULATIONS, LOCALIZATION, NAPHTHALENE, ORTHORHOMBIC FRAMEWORK, POWDER DIFFRACTION, SIMULATIONS, ZEOLITE H-ZSM-5, ZSM-5},
	isbn = {0897-4756},
	url = {<Go to ISI>://000175790100041},
	author = {Morell, H. and Angermund, K. and Lewis, A. R. and Brouwer, D. H. and Fyfe, C. A. and Gies, H.}
}
@article {4813,
	title = {Solid-state NMR and X-ray diffraction structural investigations of the p-nitroaniline/ZSM-5 complex},
	journal = {Microporous and Mesoporous Materials},
	volume = {39},
	number = {1-2},
	year = {2000},
	note = {ISI Document Delivery No.: 354ZKTimes Cited: 15Cited Reference Count: 19},
	month = {Sep},
	pages = {291-305},
	type = {Article},
	abstract = {The complex of zeolite ZSM-5 loaded with p-nitroaniline to four molecules per unit cell is of current interest as a potential non-linear optical material. A previous single crystal X-ray diffraction (XRD) investigation has claimed that the p-nitroaniline molecules line up as oriented dipole chains inside the channels of ZSM-5, and it was concluded that this ordering explains how second harmonic generation arises. In another XRD study, it was not possible to distinguish between order and disorder of the p-nitroaniline molecules. The present results from solid-state NMR and single crystal XRD experiments indicate that the p-nitroaniline molecules are disordered in the ZSM-5 channels, i.e., they do not form ordered dipole chains throughout the entire crystal. The quantitative Si-29-MAS spectrum at room temperature shows 48 peaks of equal intensity indicating disorder of the guest molecules, and the N-15-MAS spectrum at 180 K of the N-15-labeled p-nitroaniline in ZSM-5 shows a splitting of the NO2 resonance, which also implies disorder. The single crystal XRD results show that the p-nitroaniline molecules are disordered over four-sites at the channel intersection even when refined in the less symmetric Pn2(l)a space group. The final structure was refined in the orthorhombic Pnma space group to R = 0.0465. The nature of this disorder is discussed. In particular, the possibilities of disorder arising from the average of polar domains or local disorder are examined in the light of the solid-state NMR results. That the p-nitroaniline molecules are disordered in ZSM-5 implies that the mechanism by which second harmonic generation arises may be more complex than is presently assumed. (C) 2000 Elsevier Science B.V. All rights reserved.},
	keywords = {CRYSTAL STRUCTURE-ANALYSIS, DICHLOROBENZENE, harmonic generation, LOCATION, MFI, MOLECULAR-SIEVE, p-nitroaniline, second, SINGLE-CRYSTAL, SOLID-STATE NMR, x-ray diffraction, ZEOLITE H-ZSM-5, ZSM-5},
	isbn = {1387-1811},
	url = {<Go to ISI>://000089361000029},
	author = {Fyfe, C. A. and Brouwer, D. H.}
}
@inbook {3334,
	title = {One and two-dimensional solid-state NMR investigations of the three-dimensional structures of zeolite-organic sorbate complexes},
	booktitle = {Zeolites: A Refined Tool for Designing Catalytic Sites},
	series = {Studies in Surface Science and Catalysis},
	volume = {97},
	year = {1995},
	note = {ISI Document Delivery No.: BE46VTimes Cited: 2Cited Reference Count: 25Proceedings PaperInternational Zeolite SymposiumOCT 15-20, 1995QUEBEC CITY, CANADASARA BURGERHARTSTRAAT 25, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS},
	pages = {1-10},
	publisher = {Elsevier Science Publ B V},
	organization = {Elsevier Science Publ B V},
	address = {Amsterdam},
	keywords = {3-DIMENSIONAL BONDING CONNECTIVITIES, FORM, LATTICE, NATURAL-ABUNDANCE, PARA-XYLENE, TEMPERATURE, ZSM-5},
	isbn = {0-444-82130-9},
	url = {<Go to ISI>://A1995BE46V00001},
	author = {Fyfe, C. A. and Grondey, H. and Diaz, A. C. and Kokotailo, G. T. and Feng, Y. and Huang, Y. and Wongmoon, K. C. and Mueller, K. T. and Strobl, H. and Lewis, A. R.},
	editor = {Bonneviot, L. and Kaliaguine, S.}
}
@article {7023,
	title = {THE COMBINATION OF SYNCHROTRON POWDER DIFFRACTION AND HIGH-RESOLUTION SOLID-STATE NMR EXPERIMENTS},
	journal = {Journal of Physics and Chemistry of Solids},
	volume = {52},
	number = {10},
	year = {1991},
	note = {ISI Document Delivery No.: GU763Times Cited: 18Cited Reference Count: 22},
	pages = {1235-1241},
	type = {Article},
	abstract = {Structural investigations on three zeolites, ZSM-11, ZSM-12 and ZSM-5, have been carried out by a combination of high-resolution solid-state Si-28 NMR experiments and Rietveld refinement of synchrotron X-ray powder data. These techniques, being sensitive to short- and long-range order, respectively, gave a most complete picture of the structure of the solid state. Variable temperature NMR experiments of ZSM-11 revealed a displacive phase transition with a change in symmetry at about 300 K. A Rietveld refinement of a data set recorded at 373 K confirmed the proposed structure model. The structure of ZSM-12 was refined from room temperature synchrotron powder data. Space group ambiguities because of pseudo-symmetry of the silica framework of the zeolite were resolved with the aid of Si-29 NMR experiments leading to C2/c as the true space group symmetry. Si-29 NMR and X-ray studies of ZSM-5 showed that the symmetry of the crystal structure depends on the temperature, the concentration of the guest molecule, and on the number of Al atoms in the framework. A full pattern refinement of silica-ZSM-5 loaded with two molecules p-dichlorobenzene per unit cell showed that the site occupied by the sorbed molecule is not at the intersection of the channels but shifted by 1/4 along b0.},
	keywords = {3-DIMENSIONAL LATTICE CONNECTIVITIES, CRYSTAL-STRUCTURE, ORTHORHOMBIC FRAMEWORK, Rietveld refinement, Si-29 NMR, SINGLE-CRYSTAL, SORBATE, ZEOLITE H-ZSM-5, zeolites, ZSM-11, ZSM-12, ZSM-5},
	isbn = {0022-3697},
	url = {<Go to ISI>://A1991GU76300006},
	author = {Gies, H. and Marler, B. and Fyfe, C. and Kokotailo, G. and Feng, Y. and Cox, D. E.}
}
