@article {2536, title = {Reversible decomposition of mono(alpha-hydroxy)phosphines and their reaction with alpha,beta-unsaturated aldehydes}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {87}, number = {4}, year = {2009}, note = {ISI Document Delivery No.: 431IGTimes Cited: 4Cited Reference Count: 24Moiseev, Dmitry V. Marcazzan, Paolo James, Brian R.}, month = {Apr}, pages = {582-590}, type = {Article}, abstract = {{The mono (alpha-hydroxy) phosphines R2PCH(OH)R{\textquoteright} (R = Ph, R{\textquoteright} = H, Et, CH2Ph, Ph, p-X-C6H4; R = cyclohexyl, R{\textquoteright} = Ph) are prepared under solvent-free conditions by a 1:1 reaction of Ph2PH with the appropriate aldehyde, and their stabilities (with respect to reversible dissociation into reactants), studied in DMSO, Et2O, and MeOH, increase with decreased basicity of the hydroxyphosphine; for example, for the Ph2PCH (OH) C6H4-p-X phosphines, stability decreases in the order:X = CN > Cl > F > H > Me > OMe. A 1:1 room-temperature reaction of the (alpha-hydroxy) phosphines (except for R{\textquoteright} = H) with cinnamaldehyde in DMSO slowly yields the known mono-and di-phosphines Ph2PCH(Ph)CH2CHO (4a) and Ph2PCH(Ph)CH2CH(PPh2)OH (10a), and the corresponding R{\textquoteright}CHO aldehyde. In MeOH, the sequentially formed intermediates}, keywords = {(alpha-hydroxy)phosphines, alpha, beta-unsaturated aldehydes, CHEMISTRY, CHLORIDE, diphenylphosphine, FORMALDEHYDE, hydrophosphination, LIGNIN, NUCLEAR MAGNETIC-RESONANCE, PHOSPHONIUM CHLORIDE, TERTIARY PHOSPHINES, TETRAKIS(HYDROXYMETHYL)PHOSPHONIUM, TRIS(HYDROXYMETHYL)PHOSPHINE, WATER}, isbn = {0008-4042}, url = {://000265054200007}, author = {Moiseev, D. V. and Marcazzan, P. and James, Brian R.} } @article {1103, title = {Dissecting the domain structure of Cdc4p, a myosin essential light chain involved in Schizosaccharomyces pombe cytokinesis}, journal = {Biochemistry}, volume = {44}, number = {36}, year = {2005}, note = {ISI Document Delivery No.: 962ZGTimes Cited: 3Cited Reference Count: 75}, month = {Sep}, pages = {12136-12148}, type = {Article}, abstract = {Cytokinesis is the process by which one cell divides into two. Key in the cytokinetic mechanism of Schizosaccharomyces pombe is the contractile ring myosin, which consists of two heavy chains (Myo2p), two essential light chains (Cdc4p), and two regulatory light chains (R1c1p). Cdc4p is a dumbbell-shaped EF-hand protein composed of N- and C-terminal domains separated by a flexible linker. The properties of these two domains are of particular interest because each is hypothesized to have independent functions in binding different components of the cytokinesis machinery. To help define these properties, we used NMR spectroscopy to compare the structure, stability, and dynamics of the isolated N- and C-terminal domains with one another and with native Cdc4p. On the basis of invariant chemical shifts, the N-domain retains the same structure in isolation as in the context of the full-length Cdc4p, whereas the C-domain appears markedly perturbed. This perturbation results from intramolecular binding of the residual linker sequence at the N-terminus of the C-domain in a mode similar to that used by native Cdc4p to associate with target polypeptide sequences. NMR relaxation, thermal denaturation, and amide hydrogen exchange experiments also indicate that the C-domain is less stable and more dynamic than the N-domain, both in isolation and in the full-length protein. We hypothesize that these properties reflect a conformational plasticity of the C-domain, which may allow Cdc4p to interact with several regulatory or contractile ring proteins necessary for cytokinesis.}, keywords = {CALCIUM-MODULATED PROTEINS, CONFORMATIONAL CHANGE, CONTRACTILE RING, FISSION, GROUP, HYDROGEN-EXCHANGE, MUSCLE TROPONIN-C, N-15 NMR RELAXATION, NUCLEAR MAGNETIC-RESONANCE, SACCHAROMYCES-CEREVISIAE, SKELETAL-MUSCLE, YEAST}, isbn = {0006-2960}, url = {://000231771500022}, author = {Escobar-Cabrera, E. and Venkatesan, M. and Desautels, M. and Hemmingsen, S. M. and McIntosh, L. P.} } @article {4828, title = {Lattice energy-minimization calculation in the further investigation of XRD and NMR studies of zeolite frameworks}, journal = {Chemistry of Materials}, volume = {12}, number = {2}, year = {2000}, note = {ISI Document Delivery No.: 287JNTimes Cited: 6Cited Reference Count: 29}, month = {Feb}, pages = {336-342}, type = {Article}, abstract = {A knowledge of the local structure of zeolite frameworks is an important prerequisite for a detailed and quantitative understanding of e.g, catalytic processes. In the present work the sensitivity of 1D and 2D MAS NMR experiments to the local order of framework T atoms and energy-minimization calculations for the geometrical analysis of the complete zeolite framework structure are combined to provide a most detailed view of their structural properties. Correlations of the chemical shifts, delta(Si-29), with the mean distance between Si and its neighboring Si T atoms, (d) over bar(Si-Si), are presented for the three materials MFI, MEL, and MTT. Excellent agreement between experimental and computational results was obtained. In the case of MFI, this most complicated structure was used to demonstrate the viability of the method. The MTT and MEL systems showed that it is possible to deduce the unique assignment of the NMR spectra from energy-minimized structures when it is not possible using the available structural data from X-ray structure analysis. Taken together, all three investigations also demonstrate that improved structural data are obtained from lattice energy minimizations compared to those from Rietveld analysis as long as the topology of the framework is known.}, keywords = {3-DIMENSIONAL BONDING CONNECTIVITIES, CHEMICAL-SHIFTS, HIGH-TEMPERATURE, NUCLEAR MAGNETIC-RESONANCE, ORTHORHOMBIC FRAMEWORK, SI-29 MAS-NMR, SILICA POLYMORPHS, SOLID-STATE NMR, X-RAY-DIFFRACTION, ZSM-11}, isbn = {0897-4756}, url = {://000085502900017}, author = {Hochgrafe, M. and Gies, H. and Fyfe, C. A. and Feng, Y. and Grondey, H.} } @article {4955, title = {X-ray crystallographic and C-13 NMR investigations of the effects of electron-withdrawing groups on a series of pyrroles}, journal = {Organic Letters}, volume = {2}, number = {23}, year = {2000}, note = {ISI Document Delivery No.: 373RBTimes Cited: 9Cited Reference Count: 25}, month = {Nov}, pages = {3587-3590}, type = {Article}, abstract = {[GRAPHICS] A series of pyrroles substituted with various electron-withdrawing groups (EWGs) on the N atom have been synthesized and full characterization including X-ray crystal structures obtained, Analysis of C-13 chemical shifts and X-ray crystal structures reveals that a trend between decreased aromaticity and the strength of the EWG exists. Experimental results regarding alternative mechanisms of nucleophilic substitution reactions can thus be rationalized.}, keywords = {DERIVATIVES, NUCLEAR MAGNETIC-RESONANCE, THIOPHENES}, isbn = {1523-7060}, url = {://000165301700015}, author = {Thompson, A. and Gao, S. and Modzelewska, G. and Hughes, D. S. and Patrick, B. and Dolphin, D.} } @article {4611, title = {A H-1-NMR study of the permeation of glycolic acid through phospholipid membranes}, journal = {Biochimica Et Biophysica Acta-Biomembranes}, volume = {1416}, number = {1-2}, year = {1999}, note = {ISI Document Delivery No.: 162BFTimes Cited: 10Cited Reference Count: 31}, month = {Jan}, pages = {333-338}, type = {Article}, abstract = {The transmembrane permeability coefficient of the alpha-hydroxyacid, glycolic acid, has been measured for egg phosphatidylcholine large unilamellar vesicles. The determination of the vesicle concentration independent first-order rate constant for membrane transport and the permeability coefficient were made using an NMR technique employing shift agents. Both the temperature dependence and the dependence on cholesterol content were investigated. The activation energy and the Arrhenius pre-exponential factor were found to be dependent on the cholesterol content. A marked increase in both parameters was observed up to 20 mol\% cholesterol, with a further, small increase up to 50\%. The pH dependence of permeability was also investigated. An increase in permeability is observed with a decrease in pH, providing a possible explanation for the effectiveness of glycolic acid in skin treatment. (C) 1999 Published by Elsevier Science B.V. All rights reserved.}, keywords = {ACETIC-ACID, acne, aging of the, BILAYER-MEMBRANES, CHOLESTEROL, CHOLESTEROL CONTENT, glycolic acid, H-1-NMR, HUMAN ERYTHROCYTES, LAIDLAWII-B-CELLS, LARGE UNILAMELLAR VESICLES, lipid, NONELECTROLYTE, NUCLEAR MAGNETIC-RESONANCE, permeability, SKIN, transmembrane permeability, TRANSPORT, WATER}, isbn = {0005-2736}, url = {://000078324700030}, author = {Males, R. G. and Herring, F. G.} } @article {4235, title = {Characterization of a buried neutral histidine in Bacillus circulans xylanase: Internal dynamics and interaction with a bound water molecule}, journal = {Biochemistry}, volume = {37}, number = {7}, year = {1998}, note = {ISI Document Delivery No.: YZ886Times Cited: 13Cited Reference Count: 59}, month = {Feb}, pages = {1810-1818}, type = {Article}, abstract = {NMR spectroscopy was used to characterize the dynamic behavior of His149 in Bacillus circulans xylanase (BCX) and its interaction with an internal water molecule. Rate constants for the specific acid-and base-catalyzed exchange following bimolecular kinetics (EX2) of the nitrogen-bonded H-epsilon 2 of this buried, neutral histidine were determined, At pD(min) 7.0 and 30 degrees C, the lifetime for this proton is 9.9 h, corresponding to a protection factor of similar to 10(7) relative to that predicted for an exposed histidine, The apparent activation energies measured for specific acid and base catalysis (7.0 and 17.4 kcal/mol) indicate that exchange occurs via local structural fluctuations. Consistent with its buried environment, the N-epsilon 2-H bond vector of His149 shows restricted mobility, as evidenced by an order parameter S-2 = 0.83 determined from N-15 relaxation measurements, The crystal structure of BCX reveals that a conserved, buried water hydrogen-bonds to the H-epsilon 2 of His149. Strong support for this interaction in solution is provided by the observation of a negative nuclear Overhauser effect (NOE) and positive rotating-frame Overhauser effect (ROE) between His149 H-epsilon 2 and a water molecule with the same chemical shift as the bulk solvent. However, the chemical shift of H-epsilon 2 (12.2 ppm) and a D/H fractionation factor close to unity (0.89 +/- 0.02) indicate that this is nor a so-called low-barrier hydrogen bond. Lower and upper bounds on the lifetime of the internal water are estimated to be 10(-8) and 10(-3) s. Therefore the chemical exchange of solvent protons with those of His149 H-epsilon 2 and the diffusion or physical exchange of the internal water to which the histidine is hydrogen-bonded differ in rate by over 7 orders of magnitude.}, keywords = {ACTIVE-SITE, AMIDE PROTON-EXCHANGE, ASSIGNMENTS, DOMAIN, HYDROGEN-BOND, NMR-SPECTROSCOPY, NUCLEAR MAGNETIC-RESONANCE, PROTEINS, relaxation, TRICHODERMA-REESEI}, isbn = {0006-2960}, url = {://000072304200010}, author = {Connelly, G. P. and McIntosh, L. P.} } @article {4191, title = {Ethylene ligand structures of Os(CO)(4)(C2H4) and Os-2(CO)(8)(C2H4) determined by H-1 NMR in liquid crystal solvents}, journal = {Inorganic Chemistry}, volume = {37}, number = {8}, year = {1998}, note = {ISI Document Delivery No.: ZJ655Times Cited: 2Cited Reference Count: 69}, month = {Apr}, pages = {1720-1728}, type = {Article}, abstract = {The ethylene complexes Os-2(CO)(8)(mu-eta(1),eta(1)-C2H4) (1) and Os(CO)(4)(eta-C2H4) (2) have been studied by H-1 NMR in liquid crystal (nematic phase) solvents. For 1 or 2, three dipolar couplings were observed and assigned to intramolecular geminal, cis, and trans H-1-H-1 dipolar couplings. The H-1 NMR spectrum of Os(CO)(4)((CH2CH2)-C-13)(2-C-13) has also been analyzed and two additional C-13-H-1 dipolar couplinps have allowed determination of the absolute bond angles and relative bond lengths of the ethylene portion of 2 C-13. The observed dipolar couplings for 2-C-13 have been corrected for harmonic vibrations. A comparison of the ethylene geometry of 2 with that of other transition metal ethylene complexes and with free ethylene shows that the (C-2-H-4)Os unit of 2 is best described as a metallacyclopropane. Deuterium substitution is used to demonstrate liquid crystal NMR as a stereochemical probe. The H-1 NMR spectrum of Os-2(CO)(8)(mu-eta(1),eta(1)-(CH2CH2)-C-13) (1-C-13) has also been analyzed in a nematic phase solvent. The dimetallacyclobutane ring of 1-C-13 is best described as two rapidly interconverting ring-puckered conformers of C-2-symmetry. The liquid crystal NMR derived structural parameters for 1-C-13 are compared with those previously determined by neutron diffraction. The solution and solid-state structures are very similar. The ethylene complexes 1 and 2 are proposed as structural and spectroscopic models for ethylene chemisorbed on metal surfaces.}, keywords = {ANISOTROPIC LIQUIDS, CHEMISORBED ETHYLENE, INTERNAL MOTION, METAL-SURFACES, NEMATIC PHASES, NEUTRON-DIFFRACTION, NUCLEAR MAGNETIC-RESONANCE, ORIENTED MOLECULES, SPIN DIPOLAR COUPLINGS, VIBRATIONAL MODEL}, isbn = {0020-1669}, url = {://000073238400007}, author = {Bender, B. R. and Hembre, R. T. and Norton, J. R. and Burnell, E. E.} } @article {4218, title = {Prediction from molecular shape of solute orientational order in liquid crystals}, journal = {Chemical Reviews}, volume = {98}, number = {6}, year = {1998}, note = {ISI Document Delivery No.: 127TNTimes Cited: 82Cited Reference Count: 154}, month = {Sep-Oct}, pages = {2359-2387}, type = {Review}, keywords = {ATOM-ATOM POTENTIALS, COUPLINGS, ELECTRIC-FIELD GRADIENT, FLUIDS, HARD-PARTICLE, ISOMERIC STATE APPROXIMATION, MONTE-CARLO SIMULATIONS, MULTIPLE-QUANTUM H-1-NMR, NEMATIC SOLVENTS, NUCLEAR MAGNETIC-RESONANCE, PARTIALLY ORIENTED MOLECULES, SPIN DIPOLAR}, isbn = {0009-2665}, url = {://000076366800007}, author = {Burnell, E. E. and de Lange, C. A.} } @article {4336, title = {Tightening the hydrophobic belt: Effects of backbone and donor group variation on podand ligand complexes of the lanthanides}, journal = {Inorganic Chemistry}, volume = {37}, number = {7}, year = {1998}, note = {ISI Document Delivery No.: ZG944Times Cited: 44Cited Reference Count: 53}, month = {Apr}, pages = {1637-1647}, type = {Article}, abstract = {{The N4O3 tripodal aminomethylene phosphinato ligand tris(4-phenylphosphinato-3-methyl-3-azabutyl)amine (H-3-ppma) forms mono- and bis(ligand) complexes with lanthanide(III) metal ions Ln when Ln = Sm-Lu. The formation constants of the Lu (log beta(1) = 1.79, log beta(2) = 4.40) and the Yb (log beta(1) = 2.25, log beta(2) = 4.42) complexes were determined at pH = 1.5 using an unusual P-31 NMR spectroscopic method. The molecular structure of the lutetium complex [Lu(H(3)ppma)(2)](NO3)(3) . 3H(2)O (C60H96LuN11O24P6) was solved by X-ray methods; it crystallizes in the trigonal space group R(3) over barc$, with a = 19.060(1) Angstrom}, keywords = {AMINE PHENOL LIGANDS, BIOLOGICAL-SYSTEMS, CHEMISTRY, COORDINATION, DESIGN, HEPTADENTATE LIGANDS, METAL-IONS, NMR SHIFTS, NUCLEAR MAGNETIC-RESONANCE, STABILITY}, isbn = {0020-1669}, url = {://000073055700034}, author = {Lowe, M. P. and Caravan, P. and Rettig, S. J. and Orvig, Chris} } @article {3926, title = {Cationic lanthanide complexes of N,N{\textquoteright}-bis(2-pyridylmethyl)ethylenediamine-N,N{\textquoteright}-diacetic acid (H(2)bped)}, journal = {Inorganic Chemistry}, volume = {36}, number = {7}, year = {1997}, note = {ISI Document Delivery No.: WQ490Times Cited: 22Cited Reference Count: 51}, month = {Mar}, pages = {1316-1321}, type = {Article}, abstract = {A series of monocationic lanthanide complexes containing the ligand N,N{\textquoteright}-bis(2-pyridylmethyl)ethylenediamine-N,N{\textquoteright}-diacetate(2-) (bped(2-)) have been prepared and isolated as either the hexafluorophosphate or perchlorate salts. The complexes have been characterized by H-1 and C-13 NMR, +LSIMS, IR, and elemental analysis. Complex formation constants have been measured in water at 25 degrees C (mu = 0.16 M (NaCl)). log K (Ln(bped)](+)) (log K([Ln(bped)(OH)])): Ln = La, 10.81 (0.06); Ln = Nd, 11.99 (1.45); Ln = Gd, 12.37 (2.10); Ln = Ho, 12.31 (3.00); Ln = Yb, 13.32 (4.43). The stability constants for [M(bped)](+) increase from La(III) to Nd(III), plateau to Ho(III), and increase again to Yb(III), while the formation constants for [Ln(bped)(OH)] increase almost linearly with atomic number. The solution structures of the [Ln(bped)](+) complexes have been probed by multinuclear NMR (H-1, C-13, O-17) studies, and these indicate only one isomer present in solution; this isomer has 2-fold symmetry and is rigid at 20 degrees C on the NMR time scale. O-17 NMR studies of the paramagnetic lanthanides indicate that the hydration number is 3, [Ln(bped)(H2O)(2)](+), and that an overall coordination number of 9 is maintained across the lanthanide series.}, keywords = {AQUEOUS-SOLUTION, CARBOXYLATES, COMPLEXES, COORDINATION-NUMBER, EDTA, GADOLINIUM(III), NMR, NUCLEAR MAGNETIC-RESONANCE, polarization, SHIFT-REAGENTS, SHIFTS, WATER-MOLECULES}, isbn = {0020-1669}, url = {://A1997WQ49000007}, author = {Caravan, P. and Mehrkhodavandi, Parisa and Orvig, Chris} } @article {3926, title = {Cationic lanthanide complexes of N,N{\textquoteright}-bis(2-pyridylmethyl)ethylenediamine-N,N{\textquoteright}-diacetic acid (H(2)bped)}, journal = {Inorganic Chemistry}, volume = {36}, number = {7}, year = {1997}, note = {ISI Document Delivery No.: WQ490Times Cited: 22Cited Reference Count: 51}, month = {Mar}, pages = {1316-1321}, type = {Article}, abstract = {A series of monocationic lanthanide complexes containing the ligand N,N{\textquoteright}-bis(2-pyridylmethyl)ethylenediamine-N,N{\textquoteright}-diacetate(2-) (bped(2-)) have been prepared and isolated as either the hexafluorophosphate or perchlorate salts. The complexes have been characterized by H-1 and C-13 NMR, +LSIMS, IR, and elemental analysis. Complex formation constants have been measured in water at 25 degrees C (mu = 0.16 M (NaCl)). log K (Ln(bped)](+)) (log K([Ln(bped)(OH)])): Ln = La, 10.81 (0.06); Ln = Nd, 11.99 (1.45); Ln = Gd, 12.37 (2.10); Ln = Ho, 12.31 (3.00); Ln = Yb, 13.32 (4.43). The stability constants for [M(bped)](+) increase from La(III) to Nd(III), plateau to Ho(III), and increase again to Yb(III), while the formation constants for [Ln(bped)(OH)] increase almost linearly with atomic number. The solution structures of the [Ln(bped)](+) complexes have been probed by multinuclear NMR (H-1, C-13, O-17) studies, and these indicate only one isomer present in solution; this isomer has 2-fold symmetry and is rigid at 20 degrees C on the NMR time scale. O-17 NMR studies of the paramagnetic lanthanides indicate that the hydration number is 3, [Ln(bped)(H2O)(2)](+), and that an overall coordination number of 9 is maintained across the lanthanide series.}, keywords = {AQUEOUS-SOLUTION, CARBOXYLATES, COMPLEXES, COORDINATION-NUMBER, EDTA, GADOLINIUM(III), NMR, NUCLEAR MAGNETIC-RESONANCE, polarization, SHIFT-REAGENTS, SHIFTS, WATER-MOLECULES}, isbn = {0020-1669}, url = {://A1997WQ49000007}, author = {Caravan, P. and Mehrkhodavandi, Parisa and Orvig, Chris} } @article {3799, title = {Characterization of a buried neutral histidine residue in Bacillus circulans xylanase: NMR assignments, pH titration, and hydrogen exchange}, journal = {Protein Science}, volume = {5}, number = {11}, year = {1996}, note = {ISI Document Delivery No.: VQ786Times Cited: 41Cited Reference Count: 63}, month = {Nov}, pages = {2319-2328}, type = {Article}, abstract = {Bacillus circulans xylanase contains two histidines, one of which (His 156) is solvent exposed, whereas the other (His 149) is buried within its hydrophobic core. His 149 is involved in a network of hydrogen bonds with an internal water and Ser 130, as well as a potential weak aromatic-aromatic interaction with Tyr 105. These three residues, and their network of interactions with the bound water, are conserved in four homologous xylanases. To probe the structural role played by His 149, NMR spectroscopy was used to characterize the histidines in BCX. Complete assignments of the H-1, C-13, and N-15 resonances and tautomeric forms of the imidazole rings were obtained from two-dimensional heteronuclear correlation experiments. An unusual spectroscopic feature of BCX is a peak near 12 ppm arising from the nitrogen bonded H-1(epsilon 2) of His 149. Due to its solvent inaccessibility and hydrogen bonding to an internal water molecule, the exchange rate of this proton (4.0 X 10(-5) s(-1) at pH* 7.04 and 30 degrees C) is retarded by > 10(6)-fold relative to an exposed histidine. The pK(a) of His 156 is unperturbed at similar to 6.5, as measured from the pH dependence of the N-15- and H-1-NMR spectra of BCX. In contrast, His 149 has a pK(a) < 2.3, existing in the neutral (NH)-H-epsilon 2 tautomeric state under all conditions examined. BCX unfolds at low pH and 30 degrees C, and thus His 149 is never protonated significantly in the context of the native enzyme. The structural importance of this buried histidine is confirmed by the destablizing effect of substituting a phenylalanine or glutamine at position 149 in BCX.}, keywords = {ACTIVE-SITE, ALPHA-HELICES, AQUEOUS-SOLUTION, CHEMICAL-SHIFTS, ESCHERICHIA-COLI, GLYCOSYL HYDROLASES, H-1-NMR SPECTRUM, HYDROGEN-DEUTERIUM EXCHANGE, IMIDAZOLE, internal water, L-ALA-OH, NUCLEAR MAGNETIC-RESONANCE, pH titration, pK(alpha), PROTEIN HYDRATION, protein stability}, isbn = {0961-8368}, url = {://A1996VQ78600018}, author = {Plesniak, L. A. and Connelly, G. P. and Wakarchuk, W. W. and McIntosh, L. P.} } @article {3756, title = {Characterization of five-coordinate ruthenium(II) phosphine complexes by X-ray diffraction and solid-state P-31 CP/MAS NMR studies and their reactivity with sulfoxides and thioethers}, journal = {Inorganic Chemistry}, volume = {35}, number = {25}, year = {1996}, note = {ISI Document Delivery No.: VW819Times Cited: 27Cited Reference Count: 41}, month = {Dec}, pages = {7304-7310}, type = {Article}, abstract = {{P-31 CP/MAS NMR spectroscopy is examined as a method of characterization for ruthenium(II) phosphine complexes in the solid state, and the results are compared with X-ray crystallographic data determined for RuCl2(dppb)(PPh(3)) (dppb = Ph(2)P(CH2)(4)PPh(2)), RuBr2(PPh(3))(3), and the previously determined RuCl2(PPh(3))(3). Crystals of RuBr2(PPh(3))(3) (C54H45Br2P3Ru) are monoclinic, space group P2(1)/a, with a = 12.482(4) Angstrom}, keywords = {amine, ANGLE SPINNING TECHNIQUES, CATALYSTS, DERIVATIVES, IMINE, LIGANDS, NUCLEAR MAGNETIC-RESONANCE, PLATINUM(II), triphenylphosphine}, isbn = {0020-1669}, url = {://A1996VW81900019}, author = {Macfarlane, K. S. and Joshi, A. M. and Rettig, S. J. and James, Brian R.} } @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 = {://A1995RA14700041}, author = {Fyfe, C. A. and Wongmoon, K. C. and Huang, Y. and Grondey, H. and Mueller, K. T.} } @article {3266, title = {POTENTIOMETRIC, CALORIMETRIC, AND SOLUTION NMR-STUDIES OF A TRIDENTATE LIGAND WHICH HAS A MARKED PREFERENCE FOR FORMATION OF BIS(LIGAND) VERSUS MONO(LIGAND) LANTHANIDE COMPLEXES AND WHICH EXHIBITS HIGH SELECTIVITY FOR HEAVIER LANTHANIDES}, journal = {Journal of the American Chemical Society}, volume = {117}, number = {45}, year = {1995}, note = {ISI Document Delivery No.: TE739Times Cited: 69Cited Reference Count: 59}, month = {Nov}, pages = {11230-11238}, type = {Article}, abstract = {A new water-soluble N4O3 tripodal amine phenol ligand, tris(((2-hydroxy-5-sulfobenzyl)amino)ethyl)amine (H(3)TRNS) has been synthesized, and its complexation properties with six lanthanide(III) ions (Ln, Nd, Gd, Ho, Yb, Lu) have been probed. In water, the ligand coordinates in a tridentate fashion through the three phenolate oxygen atoms to give mono- and bis(ligand) complexes. The bis complexes are proposed to be 7-coordinate containing one bound water as evinced by O-17 NMR experiments on the Dy3+ complex. while the mono complexes are proposed to have a coordination number of eight or nine. The stepwise formation constants for the 1:1 and 2:1 (L:M) complexes have been measured at 25 degrees C (mu = 0.16 M NaCl) for Nd3+ (log K-1 = 6.41, log K-2 6.34), Gd3+ (log K-1 = 6.67, log K-2 = 7.69), Ho3+ (log K-1 = 7.67, log K-2 = 8.75), and Yb3+ (log K-1 = 8.53, log K-2 = 9.73). The formation constants show an increasing affinity and an unprecedented selectivity for the heavier lanthanides (beta(2(yb)) - beta(2(Nd)) = 10(5.5)). Furthermore, the stepwise stability constant for the 2:1 complex is increasingly greater than that for the 1:1 complexes of Gd3+, Ho3+, and Yb3+, while K-1 and K-2 for the 1:1 and 2:1 complexes of Nd3+ are approximately the same. Solution calorimetry shows that the selectivity for the heavier lanthanides is an enthalpic effect (Delta H-beta 2 = -45.11 (Yb) and -13.71 kJ . mol(-1) (Nd)), while the anomalous behavior in formation constants (K-2 > K-1) is predominantly entropic (Delta S-2 > Delta S-1) and is rationalized in terms of salvation of the complexes, Lanthanum(III) forms only the 1:1 complex (log K = 5.65) which precipitates from solution.}, keywords = {AGENTS, AMINE PHENOL LIGANDS, AQUEOUS, BIOLOGICAL-SYSTEMS, CHEMISTRY, EXCHANGE, HEPTADENTATE LIGANDS, METAL-IONS, NUCLEAR MAGNETIC-RESONANCE, probes, SHIFT-REAGENTS, WATER}, isbn = {0002-7863}, url = {://A1995TE73900021}, author = {Caravan, P. and Hedlund, T. and Liu, S. and Sjoberg, S. and Orvig, Chris} } @inbook {3163, title = {MUON SPIN RELAXATION STUDIES OF CYCLOHEXADIENYL RADICALS IN NAUSY}, booktitle = {Zeolites and Related Microporous Materials: State of the Art 1994}, series = {Studies in Surface Science and Catalysis}, volume = {84}, year = {1994}, note = {ISI Document Delivery No.: BD02ETimes Cited: 3Cited Reference Count: 22Proceedings Paper10th International Zeolite ConferenceJUL 17-22, 1994GARMISCH PARTENKIR, GERMANYSARA BURGERHARTSTRAAT 25, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, pages = {469-475}, publisher = {Elsevier Science Publ B V}, organization = {Elsevier Science Publ B V}, address = {Amsterdam}, abstract = {The avoided level crossing muon spin resonance (ALC-mu SR) technique is a promising new tool that can be used as a highly sensitive microscopic probe of radical motions in zeolites. We report a recent experiment in which this technique was used to identify a muonated cyclohexadienyl radical (C(6)H(6)Mu) and explore its reorientational dynamics in NaUSY. The observed evolution of the Delta M=1 ALC resonance lines are interpreted in terms of the site exchange dynamics of the radical.}, keywords = {benzene, DIFFUSION, LEVEL-CROSSING RESONANCE, LOCALIZATION, MOLECULAR-DYNAMICS, NAX, NMR, NUCLEAR MAGNETIC-RESONANCE, SODIUM-Y ZEOLITE}, isbn = {0-444-81847-2}, url = {://A1994BD02E00057}, author = {Shelley, M. and Arseneau, D. J. and Senba, M. and Pan, J. J. and Snooks, R. and Kreitzman, S. R. and Fleming, Donald G. and Roduner, E.}, editor = {Weitkamp, J. and Karge, H. G. and Pfeifer, H. and Holderich, W.} } @article {3119, title = {PORPHYRIN CHEMISTRY PERTAINING TO THE DESIGN OF ANTICANCER DRUGS .1. THE SYNTHESIS OF PORPHYRINS CONTAINING MESO-PYRIDYL AND MESO-SUBSTITUTED PHENYL FUNCTIONAL-GROUPS}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {72}, number = {9}, year = {1994}, note = {ISI Document Delivery No.: PJ994Times Cited: 37Cited Reference Count: 46}, month = {Sep}, pages = {1894-1909}, type = {Article}, abstract = {Condensation of pyrrole with a benzaldehyde and 4-pyridinecarboxaldehyde mixture yields the six possible meso-substituted phenyl or pyridyl porphyrins. Nitration of four of these has yielded 13 other porphyrins containing one to four 4-nitrophenyl moieties, and SnCl2 reduction of eight of these nitrophenylporphyrins gives the corresponding 4-aminophenyl(phenyl)- or 4-aminophenyl(phenyl)(4-pyridyl)porphyrins. Twelve of the porphyrins are new, but all 27 are fully characterized by H-1 NMR; resonances for every proton within each of the phenyl, pyridyl, and pyrrole rings are assigned. Trends in UV-VIS data are discussed, while IR and mass spectral data are noted for selected porphyrins.}, keywords = {METALLOPORPHYRINS, MODEL, NUCLEAR MAGNETIC-RESONANCE, OXYGEN, TETRAARYLPORPHYRINS, TUMORS}, isbn = {0008-4042}, url = {://A1994PJ99400002}, author = {Meng, G. Z. G. and James, Brian R. and Skov, K. A.} } @article {2808, title = {WATER PENETRATION IN NYLON-6,6 - ABSORPTION, DESORPTION, AND EXCHANGE STUDIED BY NMR MICROSCOPY}, journal = {Journal of Polymer Science Part a-Polymer Chemistry}, volume = {31}, number = {1}, year = {1993}, note = {ISI Document Delivery No.: KB969Times Cited: 22Cited Reference Count: 17}, month = {Jan}, pages = {159-168}, type = {Article}, abstract = {The uptake of water by nylon 6,6 [42DB Adipure (trade name of Dupont Canada Inc.)] at 100-degrees-C has been monitored by a combination of one-dimensional proton NMR spectroscopy, relaxation time (T1 and T2) measurements and proton microscopic NMR imaging techniques. The relaxation times of the water absorbed into the nylon matrix are very short at room temperature, (T2 < 1 ms and T1 almost-equal-to 1 s) indicating that the water is located in a highly restricted environment and suggesting that strong interactions exist between the absorbed water and the polymer. The diffusion profiles measured at room temperature indicate that the diffusion of water into nylon 6,6 at 100-degrees-C is Case I Fickian diffusion. The spatial dependence of the T2 relaxation time constant and its variation with the water content was also examined. The results reveal that both T2 and T2* decrease toward the center of the sample in samples that have a concentration gradient of sorbed water. In fully saturated samples, no spatial dependence was observed. The overall values of T2 and T2* are also observed to increase as a function of exposure time. An evaluation of the desorption process at room temperature and at 100-degrees-C was performed. A continuous, exponentially decreasing solvent profile was observed for the desorption process which again indicates Case I Fickian kinetics. The exchange process of external bulk and atmospheric water with deuterium oxide (D2O) saturated nylon rods has also been studied using the microscopic imaging technique.}, keywords = {6, mobility, NMR MICROSCOPY, NUCLEAR MAGNETIC-RESONANCE, NYLON-6, WATER ABSORPTION}, isbn = {0887-624X}, url = {://A1993KB96900019}, author = {Fyfe, C. A. and Randall, L. H. and Burlinson, N. E.} } @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 = {://A1992HQ81400014}, author = {Fyfe, C. A. and Zhang, Y. and Aroca, P.} } @article {7240, title = {HIGH-RESOLUTION C-13 AND N-15 NMR INVESTIGATIONS OF THE MECHANISM OF THE CURING REACTIONS OF CYANATE-BASED POLYMER RESINS IN SOLUTION AND THE SOLID-STATE}, journal = {Macromolecules}, volume = {25}, number = {23}, year = {1992}, note = {ISI Document Delivery No.: JX890Times Cited: 43Cited Reference Count: 22}, month = {Nov}, pages = {6289-6301}, type = {Article}, abstract = {The mechanism of the curing reactions of cyanate polymer resins based on Bisphenol A dicyanate has been investigated both in solution and in the solid state by NMR spectroscopic techniques. To increase S/N and to unambiguously characterize the reactions of the cyanate functionalities, C-13- and N-15-enriched cyanate resins and monocyanate model compounds were used, the latter yielding soluble and isolable analogs. In solution, the main reaction is formation of triazine rings as identified by NMR and MS techniques and characterized by single-crystal X-ray diffraction on an isolated crystalline compound from the monocyanate model compound. Side products are formed by the reaction of the cyanate functionalities with trace water present in the solvent but there is no NMR evidence for the formation of dimeric or other intermediate species prior to triazine ring formation. The isolated resins from the solution curing and also those formed directly by heat curing of the neat resin were characterized by high-resolution solid-state NMR. In the former case triazine ring formation and the presence of side products were confirmed by both C-13 and N-15 solid-state NMR and their proportions quantified. In the case of the neat resin, the curing reaction is shown to be almost quantitative. This is rationalized in terms of the very strong intermolecular intercyanate bonding interactions observed in the crystal structure of the Bisphenol A dicyanate monomer obtained from a single-crystal X-ray diffraction experiment.}, keywords = {MAGIC-ANGLE, NUCLEAR MAGNETIC-RESONANCE, SPECTRA}, isbn = {0024-9297}, url = {://A1992JX89000028}, author = {Fyfe, C. A. and Niu, J. and Rettig, S. J. and Burlinson, N. E. and Reidsema, C. M. and Wang, D. W. and Poliks, M.} } @article {7241, title = {OBSERVATION OF HETEROGENEOUS TRACE (0.4-PERCENT W/W) WATER-UPTAKE IN BISPHENOL A POLYCARBONATE BY NMR IMAGING}, journal = {Chemistry of Materials}, volume = {4}, number = {2}, year = {1992}, note = {ISI Document Delivery No.: HL702Times Cited: 6Cited Reference Count: 17}, month = {Mar-Apr}, pages = {267-271}, type = {Article}, abstract = {The uptake of water by injection-molded bars of bisphenol A polycarbonate (Lexan 121 resin) has been monitored by a combination of one-dimensional proton NMR spectroscopy, relaxation time (T1 and T2) measurements, and microscopic imaging techniques. The bulk of the water absorbed in the initial stages (20-24 h) of 100-degrees-C water exposure is uniformly distributed throughout the polymer with a trace amount of the water found in clusters of 200-300-mu-m in size. The water that has aggregated to form these clusters is more mobile, having a T2 relaxation time 20 times longer than that found for the uniformly distributed water. At longer exposure times (30-40 days) the number of clusters is observed to increase. Although the total amount of water adsorbed is considerably less than 1 \% w/w, good-quality images are obtained, demonstrating that the NMR microimaging technique can successfully monitor even trace levels of solvent if the molecules are relatively mobile.}, keywords = {DIFFUSION, mobility, NUCLEAR MAGNETIC-RESONANCE, POLYMERS}, isbn = {0897-4756}, url = {://A1992HL70200010}, author = {Fyfe, C. A. and Randall, L. H. and Burlinson, N. E.} } @article {7038, title = {HYDRIDO THIOLATO AND THIOLATO COMPLEXES OF RUTHENIUM(II) CARBONYL PHOSPHINES}, journal = {Inorganic Chemistry}, volume = {30}, number = {24}, year = {1991}, note = {ISI Document Delivery No.: GR813Times Cited: 52Cited Reference Count: 76}, month = {Nov}, pages = {4617-4627}, type = {Article}, abstract = {{Oxidative addition of RSH (R = H, alkyl, aryl) or RSSR (R = aryl) to Ru(CO)2L3 (L = PPh3, 1) yields respectively cct-RuH(SR)(CO)2L2 (type 2) (cct = cis,cis,trans) or cct-Ru(SR)2(CO)2L2 (type 3); a hydrido selenolate species is made similarly using PhSeH. Methods for in situ formation of corresponding mixed bis(thiolate) species are also given. 1 is generally unreactive toward thioethers, although with propylene sulfide cct-Ru(eta-2-S2) (CO)2L2 is produced. Metathesis reactions of cct-RuCl2(CO)2L2 with NaSR salts yield 3 (R = aryl) or, when R = Et, cct-RuCl(SEt)(CO)2L2 or [L(CO)2Ru(mu-2-SEt)2(mu-3-SEt)Na(THF)]2 (4), depending on reaction conditions. The complexes are characterized by IR spectroscopy, H-1, P-31, and, in some cases, C-13 NMR spectroscopy, and for 2g and 3g (R = SC6H4pMe) and 4, X-ray crystallography. All three complexes crystallized in the space group P1BAR. For 2g}, keywords = {CHEMISTRY, DERIVATIVES, MECHANISM, METHYLDISULFIDO-LIGAND, MOLECULAR-STRUCTURE, NUCLEAR MAGNETIC-RESONANCE, OSMIUM, REACTIVITY, TRANSITION-METALS, X-RAY CRYSTAL}, isbn = {0020-1669}, url = {://A1991GR81300031}, author = {Jessop, P. G. and Rettig, S. J. and Lee, C. L. and James, Brian R.} } @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 = {://A1991GP76400014}, author = {Fyfe, C. A. and Feng, Y. and Grondey, H. and Kokotailo, G. T. and Gies, H.} } @article {7036, title = {STEREOSELECTIVITY OF C(3) METHYLATION AND ALDOL CONDENSATION OF CAMPHOR AND DERIVATIVES}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {69}, number = {3}, year = {1991}, note = {ISI Document Delivery No.: FE808Times Cited: 14Cited Reference Count: 38}, month = {Mar}, pages = {558-566}, type = {Article}, abstract = {The stereoselectivity of methylation and aldol condensation of camphor and derivatives is determined by the presence or absence of a C(7) syn-methyl group and (or) C(5) and C(6) endo-hydrogen atoms.}, keywords = {APPROACH, BICYCLO<2.2.1>HEPTANES, C(3)ALDOL, C(3)METHYLATION, CAMPHOR, NUCLEAR MAGNETIC-RESONANCE, ORGANIC-SYNTHESIS, PSEUDOGUAIANOLIDES, STEREOCONTROLLED, VITAMIN-D METABOLITES}, isbn = {0008-4042}, url = {://A1991FE80800029}, author = {Hutchinson, J. H. and Li, D. L. F. and Money, T. and Palme, M. and Agharahimi, M. R. and Albizati, K. F.} } @article {7039, title = {SYNTHESIS AND CHARACTERIZATION OF DIHALOGENORUTHENIUM(IV)-TETRAPHENYLPORPHYRIN, DIPHENYLRUTHENIUM(IV)-TETRAPHENYLPORPHYRIN, AND PHENYLRUTHENIUM(III)-TETRAPHENYLPORPHYRIN COMPLEXES, INCLUDING THE CRYSTAL-STRUCTURE OF RU(TPP)BR2}, journal = {Inorganic Chemistry}, volume = {30}, number = {25}, year = {1991}, note = {ISI Document Delivery No.: GT938Times Cited: 40Cited Reference Count: 94}, month = {Dec}, pages = {4766-4771}, type = {Article}, abstract = {{The paramagnetic (S = 1) Ru(TPP)X2 complexes (X = halide) are made by treatment of [Ru(TPP)]2 with HBr, HCl, or I2 (TPP = the dianion of 5,10,15,20-tetraphenylporphyrin). The dibromo species (2) crystallizes in the tetragonal system, space group C4h5-I4/m, with a = 13.686 (9) angstrom}, keywords = {CARBONYL-COMPLEXES, DIOXYGEN INSERTION, IRON(II) PORPHYRINS, MOLECULAR-STRUCTURES, NUCLEAR MAGNETIC-RESONANCE, OXO COMPLEXES, PORPHYRIN COMPLEXES, redox properties, RUTHENIUM PORPHYRIN, Schiff-base}, isbn = {0020-1669}, url = {://A1991GT93800017}, author = {Ke, M. and Sishta, C. and James, Brian R. and Dolphin, D. and Sparapany, J. W. and Ibers, J. A.} }