@article {1611,
	title = {Monitoring structural transformations in crystals. 8. Monitoring molecules and a reaction center during a solid-state Yang photocyclization},
	journal = {Acta Crystallographica Section B-Structural Science},
	volume = {62},
	year = {2006},
	note = {ISI Document Delivery No.: 018ZGTimes Cited: 19Cited Reference Count: 22Part 1},
	month = {Feb},
	pages = {128-134},
	type = {Article},
	abstract = {Structural changes taking place in a crystal during an intramolecular photochemical reaction [ the Yang photocyclization of the alpha- methylbenzylamine salt with 1-( 4- carboxybenzoyl)1- methyladamantane] were monitored step- by- step using X- ray structure analysis. This is the first example of such a study carried out for an intramolecular photochemical reaction. During the photoreaction, both the reactant and product molecules change their orientation, but the reactant changes more rapidly after the reaction is about 80\% complete. The distance between directly reacting atoms in the reactant molecule is almost constant until about 80\% reaction progress and afterwards decreases. The torsion angle defined by the reactant atoms that form the cyclobutane ring also changes in the final stages of the photoreaction. These phenomena are explained in terms of the influence of many product molecules upon a small number of reacting molecules. The adamantane portion shifts more than the remaining part of the anionic reactant species during the reaction, which is explained in terms of hydrogen bonding. The structural changes are accompanied by changes in the cell constants. The results obtained in the present study are compared with analogous results published for intermolecular reactions.},
	keywords = {INCLUSION CRYSTALS, PHOTO-DIMERIZATION, PHOTODIMERIZATION, SINGLE-CRYSTAL, X-RAY},
	isbn = {0108-7681},
	url = {<Go to ISI>://000235803600014},
	author = {Turowska-Tyrk, I. and Trzop, E. and Scheffer, J. R. and Chen, S.}
}
@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 {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.}
}
@article {4327,
	title = {An investigation of the yang photocyclization reaction in the solid state: Asymmetric induction studies and crystal structure-reactivity relationships},
	journal = {Journal of the American Chemical Society},
	volume = {120},
	number = {49},
	year = {1998},
	note = {ISI Document Delivery No.: 149MWTimes Cited: 101Cited Reference Count: 61},
	month = {Dec},
	pages = {12755-12769},
	type = {Article},
	abstract = {The Norrish/Yang type II photochemistry of 16 ketones having the basic cis-4-tert-butyl-1-benzoylcyclohexane or 2-benzoyladamantane structure has been investigated in the solid state and solution. In both media, ketones bearing methyl substituents alpha to the benzoyl group undergo stereoselective Yang photocyclization to afford endo-arylcyclobutanols. Quantum yield and quenching studies in solution show that the reactions are efficient triplet-mediated processes. Asymmetric induction studies were carried out by providing the reactants with carboxylic acid substituents to which "ionic chiral auxiliaries" were attached through salt formation with optically active amines. Irradiation of the salts (17 in total) in solution gave racemic cyclobutanols, but in the crystalline state, moderate to near-quantitative enantiomeric excesses were obtained. Single crystal X-ray diffraction studies were successfully performed on 10 neutral ketones and four salts. This allowed the reactive gamma-hydrogen atoms to be identified and the distance and angular parameters associated with their abstraction to be tabulated. For the 14 compounds whose crystal structures were determined, the average value of d, the C=O ... H abstraction distance, was 2.61 +/- 0.07 Angstrom, and the values of omega (the gamma-hydrogen out-of-plane angle), Delta (the C=O ... H, angle) and a (the C-H-gamma... O angle) were 53 +/- 11, 84 +/- 7, and 115 +/- 2 degrees, respectively. In a similar manner, the geometric parameters associated with the ring closure reactions of the intermediate 1,4-hydroxy biradicals were estimated from the crystallographic data. This indicates that the biradicals are 66.5 +/- 9.8 and 32.7 +/- 3.2 degrees out of alignment for cleavage, but that they are well oriented for cyclization, with radical separations (D) of 3.08 +/- 0.09 Angstrom. For one of the salts in the adamantane series, the solid-state photoreaction was shown to be topotactic; that is, a single crystal of the reactant salt was transformed quantitatively into a single crystal of the corresponding cyclobutanol salt. Since the absolute configuration of the ionic chiral auxiliary in this case was known, this permitted the absolute steric course of the reaction to be mapped by X-ray crystallography and the abstracted gamma-hydrogen to be identified unequivocally. In addition, the crystal structure of a partially reacted crystal containing 60\% product and 40\% reactant was successfully determined. This showed that the two compounds in the mixed crystal have nearly identical shapes and orientations, thus accounting for the single crystal nature of the process. Finally, it was found that ketones lacking methyl substituents alpha to the benzoyl group an either photochemically unreactive or undergo Norrish type II cleavage. Possible reasons for this difference in behavior are presented and discussed.},
	keywords = {BIRADICALS, CHEMISTRY, CONFORMATIONAL MEMORY, HYDROGEN-ATOM TRANSFERS, II PHOTOPROCESSES, KETONES, ORGANIC-PHOTOCHEMISTRY, PHENYL, POLYMERIZATION, SINGLE-CRYSTAL, TRANSITION STRUCTURES, TRIPLET},
	isbn = {0002-7863},
	url = {<Go to ISI>://000077610100007},
	author = {Leibovitch, M. and Olovsson, G. and Scheffer, J. R. and Trotter, J.}
}
@article {4327,
	title = {An investigation of the yang photocyclization reaction in the solid state: Asymmetric induction studies and crystal structure-reactivity relationships},
	journal = {Journal of the American Chemical Society},
	volume = {120},
	number = {49},
	year = {1998},
	note = {ISI Document Delivery No.: 149MWTimes Cited: 101Cited Reference Count: 61},
	month = {Dec},
	pages = {12755-12769},
	type = {Article},
	abstract = {The Norrish/Yang type II photochemistry of 16 ketones having the basic cis-4-tert-butyl-1-benzoylcyclohexane or 2-benzoyladamantane structure has been investigated in the solid state and solution. In both media, ketones bearing methyl substituents alpha to the benzoyl group undergo stereoselective Yang photocyclization to afford endo-arylcyclobutanols. Quantum yield and quenching studies in solution show that the reactions are efficient triplet-mediated processes. Asymmetric induction studies were carried out by providing the reactants with carboxylic acid substituents to which "ionic chiral auxiliaries" were attached through salt formation with optically active amines. Irradiation of the salts (17 in total) in solution gave racemic cyclobutanols, but in the crystalline state, moderate to near-quantitative enantiomeric excesses were obtained. Single crystal X-ray diffraction studies were successfully performed on 10 neutral ketones and four salts. This allowed the reactive gamma-hydrogen atoms to be identified and the distance and angular parameters associated with their abstraction to be tabulated. For the 14 compounds whose crystal structures were determined, the average value of d, the C=O ... H abstraction distance, was 2.61 +/- 0.07 Angstrom, and the values of omega (the gamma-hydrogen out-of-plane angle), Delta (the C=O ... H, angle) and a (the C-H-gamma... O angle) were 53 +/- 11, 84 +/- 7, and 115 +/- 2 degrees, respectively. In a similar manner, the geometric parameters associated with the ring closure reactions of the intermediate 1,4-hydroxy biradicals were estimated from the crystallographic data. This indicates that the biradicals are 66.5 +/- 9.8 and 32.7 +/- 3.2 degrees out of alignment for cleavage, but that they are well oriented for cyclization, with radical separations (D) of 3.08 +/- 0.09 Angstrom. For one of the salts in the adamantane series, the solid-state photoreaction was shown to be topotactic; that is, a single crystal of the reactant salt was transformed quantitatively into a single crystal of the corresponding cyclobutanol salt. Since the absolute configuration of the ionic chiral auxiliary in this case was known, this permitted the absolute steric course of the reaction to be mapped by X-ray crystallography and the abstracted gamma-hydrogen to be identified unequivocally. In addition, the crystal structure of a partially reacted crystal containing 60\% product and 40\% reactant was successfully determined. This showed that the two compounds in the mixed crystal have nearly identical shapes and orientations, thus accounting for the single crystal nature of the process. Finally, it was found that ketones lacking methyl substituents alpha to the benzoyl group an either photochemically unreactive or undergo Norrish type II cleavage. Possible reasons for this difference in behavior are presented and discussed.},
	keywords = {BIRADICALS, CHEMISTRY, CONFORMATIONAL MEMORY, HYDROGEN-ATOM TRANSFERS, II PHOTOPROCESSES, KETONES, ORGANIC-PHOTOCHEMISTRY, PHENYL, POLYMERIZATION, SINGLE-CRYSTAL, TRANSITION STRUCTURES, TRIPLET},
	isbn = {0002-7863},
	url = {<Go to ISI>://000077610100007},
	author = {Leibovitch, M. and Olovsson, G. and Scheffer, J. R. and Trotter, J.}
}
@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 {2928,
	title = {XPS STUDIES OF THE STABILITY AND REACTIVITY OF THIN-FILMS OF OXIDIZED ZIRCONIUM},
	journal = {Applied Surface Science},
	volume = {72},
	number = {3},
	year = {1993},
	note = {ISI Document Delivery No.: MF104Times Cited: 21Cited Reference Count: 32},
	month = {Nov},
	pages = {237-244},
	type = {Article},
	abstract = {X-ray photoelectron spectroscopy (XPS) has been used to characterize thin films formed by the deposition of zirconium on to gold foil. With deposition rates of the order of 1 angstrom min-1, in the presence of an atmosphere of 10(-9) mbar H2O, the film has an outer region Of ZrO2 and inner regions of a lower oxidation state material, ZrO(x), and Zr-Au alloy. Initially both ZrO(x) and Zr-Au alloy are oxidized by either H2O or O2 at 300-degrees-C, although this process is hindered as the ZrO2 layer gets thicker. However, even with the protective oxide layer, heating in 5 x 10(-7) mbar D2 (with a partial pressure of 10(-9) mbar H2O) can convert ZrO(x) to ZrO2, a reaction apparently facilitated by migrating D atoms.},
	keywords = {ADSORPTION, AES, BINDING-ENERGY SHIFTS, electron, HYDROGEN, OXIDATION, OXYGEN, RAY PHOTOELECTRON-SPECTROSCOPY, SINGLE-CRYSTAL, SURFACES, ZR},
	isbn = {0169-4332},
	url = {<Go to ISI>://A1993MF10400004},
	author = {Wang, Y. M. and Li, Y. S. and Wong, P. C. and Mitchell, K. A. R.}
}
@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.}
}
