The Experts below are selected from a list of 162 Experts worldwide ranked by ideXlab platform

Motohiro Mizuno - One of the best experts on this subject based on the ideXlab platform.

  • Solid-State 2H NMR Studies of Molecular Motion in Functional Materials
    Experimental Approaches of NMR Spectroscopy, 2018
    Co-Authors: Motohiro Mizuno
    Abstract:

    In this chapter, the analysis of molecular motion in solid materials, which is connected with the function of those materials, using 2H NMR spectroscopy is described. The line shape of a 2H NMR Spectrum, which is dominated by the quadrupole interaction, is very sensitive to molecular motion. The mode and rate of molecular motion in the dynamic range of 104–107 Hz can be obtained by the line shape analysis of a 2H NMR broad line Spectrum of a powder sample using spectral simulation. Molecular motion in the order of 103 and 108 Hz can be analyzed by a line shape and line width of a 2H NMR Quadrupolar Carr-Purcell-Meiboom-Gill (QCPMG) Spectrum. The analysis of molecular motion in paramagnetic materials is possible by simulation of the 2H NMR Spectrum, including paramagnetic effects. The methods used to simulate these spectra are explained. In addition, the application of these methods to porous coordination polymer (PCP)/metal organic framework (MOF), proton-conducting material, and spin-crossover material is introduced.

  • Molecular orientation of hydrogen-bonded liquid crystal (6BA)2-(BPy)x as Studied by 2H NMR
    Hyperfine Interactions, 2014
    Co-Authors: Motohiro Mizuno, Y. Higashima, A. Yamashita, Y. Ishida, Tatsuya Miyatou, Yoshihide Kumagai, Ryutaro Ohashi, Tomonori Ida
    Abstract:

    The thermal properties of hydrogen-bonded liquid crystal (6BA)2-(BPy)x (6BA: 4-n-hexylbenzoicacid, BPy: 4,4’-bipyridine) were investigated by DSC. Two liquid crystal phases (LCI, LCII) were found for (6BA)2-(BPy)0.5. In LCII, the distribution of the orientation of molecules was larger than in LCI. The order parameter S of molecular orientation in the liquid crystal phase was estimated from a 2H NMR Spectrum. S decreased rapidly around the LCI-LCII phase transition. The increase in orientational fluctuation of the 6BA dimer with an open dimer structure is predicted to cause the rapid decrease of S.

  • 2H and 13C NMR studies of molecular orientation and dynamics in liquid crystal 6BA
    Journal of Physics and Chemistry of Solids, 2010
    Co-Authors: You Suzuki, Motohiro Mizuno, Tomonori Ida, Takashi Uta, Miwa Murakami, Masataka Tansho, Tadashi Shimizu
    Abstract:

    Abstract The dynamics and orientation of dimers accompanying the formation and destruction of hydrogen bonds in the nematic phases of 4-n-hexylbenzoic acid (6BA) were studied by 13C and 2H NMR. The orientational order parameter S in the nematic phase was estimated from the quadrupole splitting of the 2H NMR Spectrum. The intermolecular interaction energy for the molecular order in the nematic phase decreased with increasing temperature. The flexibility of dimers due to the destruction of the hydrogen bond is closely related to a decrease in the intermolecular interaction energy. The proportion of 2H NMR spin–lattice relaxation time (T1) to S, which reveals the coupling of the orientational fluctuations with the hydrogen bonding processes, was observed.

  • Dynamics of [Zn(D2O)6]2+ in [Zn(D2O)6][SiF6] crystal as studied by 1D, 2D spectra and spin-lattice relaxation time of 2H NMR
    Chemical Physics, 2008
    Co-Authors: Takashi Araya, Motohiro Mizuno, Akira Niwa, Kazunaka Endo
    Abstract:

    Abstract The dynamics of [Zn(D2O)6]2+ in [Zn(D2O)6][SiF6] was investigated by 2H NMR one-dimensional spectra, two-dimensional exchange spectra and spin-lattice relaxation time (T1). The lineshapes of those spectra and T1 were dominated by the 180° flip of the water molecules and the reorientation of [Zn(D2O)6]2+ about the C3 axis. The variation of lineshape of the one-dimensional Spectrum below room temperature can be explained by only the 180° flip of the water molecules. The Spectrum at room temperature showed a typical shape due to the rapid 180° flip of water molecules. The change in lineshape of the one-dimensional 2H NMR Spectrum is caused by the three-site jump of [Zn(D2O)6]2+ about its C3 axis above 333 K. Information of the reorientation of [Zn(D2O)6]2+ below 333 K could not be obtained from the one-dimensional Spectrum and T1. In this temperature range, the two-dimensional exchange Spectrum was effective for analysis of molecular motion. The effects of multiple motions, the 180° flip of the water molecules and the reorientation of [Zn(D2O)6]2+ about the C3 axis, on the lineshape of the two-dimensional exchange Spectrum were studied using spectral simulation.

  • Effects of strong paramagnetic interactions on solid-state deuterium NMR spectra
    Chemical Physics Letters, 2005
    Co-Authors: Motohiro Mizuno, Naohisa Itakura, Kazunaka Endo
    Abstract:

    Abstract The method for analyzing the 2H NMR Spectrum affected by strong paramagnetic interaction is discussed. The 2H NMR spectral simulation including the effects of paramagnetic shift and paramagnetic spin–spin relaxation was performed for several molecular motions. The contribution of distant paramagnetic ions to the paramagnetic shift and the effect of anisotropic spin–spin relaxation on the lineshape of the 2H NMR Spectrum were investigated by the spectral simulation. The temperature variation of 2H NMR Spectrum of [Mn(H2O)6][SiF6] observed by the Exorcycled quadrupole-echo sequence was well reproduced using the proposed method.

Kazunaka Endo - One of the best experts on this subject based on the ideXlab platform.

  • Dynamics of [Zn(D2O)6]2+ in [Zn(D2O)6][SiF6] crystal as studied by 1D, 2D spectra and spin-lattice relaxation time of 2H NMR
    Chemical Physics, 2008
    Co-Authors: Takashi Araya, Motohiro Mizuno, Akira Niwa, Kazunaka Endo
    Abstract:

    Abstract The dynamics of [Zn(D2O)6]2+ in [Zn(D2O)6][SiF6] was investigated by 2H NMR one-dimensional spectra, two-dimensional exchange spectra and spin-lattice relaxation time (T1). The lineshapes of those spectra and T1 were dominated by the 180° flip of the water molecules and the reorientation of [Zn(D2O)6]2+ about the C3 axis. The variation of lineshape of the one-dimensional Spectrum below room temperature can be explained by only the 180° flip of the water molecules. The Spectrum at room temperature showed a typical shape due to the rapid 180° flip of water molecules. The change in lineshape of the one-dimensional 2H NMR Spectrum is caused by the three-site jump of [Zn(D2O)6]2+ about its C3 axis above 333 K. Information of the reorientation of [Zn(D2O)6]2+ below 333 K could not be obtained from the one-dimensional Spectrum and T1. In this temperature range, the two-dimensional exchange Spectrum was effective for analysis of molecular motion. The effects of multiple motions, the 180° flip of the water molecules and the reorientation of [Zn(D2O)6]2+ about the C3 axis, on the lineshape of the two-dimensional exchange Spectrum were studied using spectral simulation.

  • Effects of strong paramagnetic interactions on solid-state deuterium NMR spectra
    Chemical Physics Letters, 2005
    Co-Authors: Motohiro Mizuno, Naohisa Itakura, Kazunaka Endo
    Abstract:

    Abstract The method for analyzing the 2H NMR Spectrum affected by strong paramagnetic interaction is discussed. The 2H NMR spectral simulation including the effects of paramagnetic shift and paramagnetic spin–spin relaxation was performed for several molecular motions. The contribution of distant paramagnetic ions to the paramagnetic shift and the effect of anisotropic spin–spin relaxation on the lineshape of the 2H NMR Spectrum were investigated by the spectral simulation. The temperature variation of 2H NMR Spectrum of [Mn(H2O)6][SiF6] observed by the Exorcycled quadrupole-echo sequence was well reproduced using the proposed method.

John G Jones - One of the best experts on this subject based on the ideXlab platform.

  • quantifying endogenous glucose production and contributing source fluxes from a single 2H NMR Spectrum
    Magnetic Resonance in Medicine, 2009
    Co-Authors: Patricia M Nunes, John G Jones
    Abstract:

    Endogenous glucose production (EGP), gluconeogenic and glycogenolytic fluxes by analysis of a single (2)H-NMR Spectrum is demonstrated with 6-hr and 24-hr fasted rats. Animals were administered [1-(2)H, 1-(13)C]glucose, a novel tracer of glucose turnover, and (2)H(2)O. Plasma glucose enrichment from both tracers was quantified by (2)H-NMR analysis of monoacetone glucose. The 6-hr fasted group (n = 7) had EGP rates of 95.6 +/- 13.3 micromol/kg/min, where 56.2 +/- 7.9 micromol/kg/min were derived from PEP; 12.1 +/- 2.1 micromol/kg/min from glycerol, and 32.1 +/- 4.9 micromol/kg/min from glycogen. The 24-hr fasted group (n = 7) had significantly lower EGP rates (52.8 +/- 7.2 micromol/kg/min, P = 0.004 vs. 6 hr) mediated by a significantly reduced contribution from glycogen (4.7 +/- 5.9 micromol/kg/min, P = 0.02 vs. 6 hr) while PEP and glycerol contributions were not significantly different (39.5 +/- 3.9 and 8.5 +/- 1.2 micromol/kg/min, respectively). These estimates agree with previous assays of EGP fluxes in fasted rats obtained by multinuclear NMR analyses of plasma glucose enrichment from (2)H(2)O and (13)C-glucose tracers.

  • Quantitation of Gluconeogenesis by 2H Nuclear Magnetic Resonance Analysis of Plasma Glucose Following Ingestion of 2H2O
    Analytical biochemistry, 2000
    Co-Authors: John G Jones, Rui A. Carvalho, A. Dean Sherry, Craig R. Malloy
    Abstract:

    Abstract We present a simple 2H NMR assay of the fractional contribution of gluconeogenesis to hepatic glucose output following ingestion of 2H2O. The assay is based on the measurement of relative deuterium enrichment in hydrogens 2 and 3 of plasma glucose. Plasma glucose was enzymatically converted to gluconate, which displays fully resolved deuterium 2 and 3 resonances in its 2H NMR Spectrum at 14.1 T. The signal intensity of deuterium 3 relative to deuterium 2 in the gluconate derivative as quantitated by 2H NMR was shown to provide a precise and accurate measurement of glucose enrichment in hydrogen 3 relative to hydrogen 2. This measurement was used to estimate the fractional contribution of gluconeogenesis to hepatic glucose output for two groups of rats; one group was fasted for 7 h and the other was fasted for 29 h. Rats were administered 2H2O to enrich total body water to 5% over the last 4–5 h of each fasting period. For the 7-h fasted group, the hydrogen 3/hydrogen 2 enrichment ratio of plasma glucose was 0.32 ± 0.09 (n = 7). This indicates that gluconeogenesis contributed 32 ± 9% of total hepatic glucose output with glycogenolysis contributing the remainder. For the 29-h fasted group, the hydrogen 3/hydrogen 2 enrichment ratio of plasma glucose was 0.81 ± 0.10 (n = 6), indicating that gluconeogenesis supplied the bulk of hepatic glucose output (81 ± 10%).

Darlene J. Semchyschyn - One of the best experts on this subject based on the ideXlab platform.

  • 2H NMR and polyelectrolyte-induced domains in lipid bilayers.
    Solid state nuclear magnetic resonance, 2000
    Co-Authors: P M Macdonald, Kevin J. Crowell, C M Franzin, P Mitrakos, Darlene J. Semchyschyn
    Abstract:

    2H NMR studies of polyelectrolyte-induced domain formation in lipid bilayer membranes are reviewed. The 2H NMR Spectrum of choline-deuterated phosphatidylcholine (PC) reports on any and all sources of lipid bilayer surface charge, since these produce a conformation change in the choline head group of PC, manifest as a change in the 2H NMR quadrupolar splitting. In addition, homogeneous and inhomogeneous surface charge distributions are differentiated. Adding polyelectrolytes to lipid bilayers consisting of mixtures of oppositely charged and zwitterionic lipids produces 2H NMR spectra which are superpositions of two Pake sub-spectra: one corresponding to a polyelectrolyte-bound lipid population and the other to a polyelectrolyte-free lipid population. Quantitative analysis of the quadrupolar splittings and spectral intensities of the two sub-spectra indicate that the polyelectrolyte-bound populations is enriched with oppositely charged lipid, while the polyelectrolyte-free lipid population is correspondingly depleted. The same domain-segregation effect is produced whether cationic polyelectrolytes are added to anionic lipid bilayers or anionic polyelectrolytes are added to cationic lipid bilayers. The 2H NMR spectra permit a complete characterization of domain composition and size. The anion:cation ratio within the domains is always stoichiometric, as expected for a process driven by Coulombic interactions. The zwitterionic lipid content of the domains is always statistical, reflecting the systems tendency to minimize the entropic cost of demixing charged lipids into domains. Domain formation is observed even with rather short polyelectrolytes, suggesting that individual polyelectrolyte chains aggregate at the surface to form "superdomains". Overall, the polyelectrolyte bound at the lipid bilayer surface appears to lie flat along the surface and to be essentially immobilized through its multiple electrostatic contacts.

  • Polyelectrolyte-induced domains in lipid bilayer membranes: the deuterium NMR perspective.
    Biochemistry and cell biology = Biochimie et biologie cellulaire, 1998
    Co-Authors: Peter M. Macdonald, Peter Mitrakos, Carla M. Franzin, Kevin J. Crowell, Darlene J. Semchyschyn
    Abstract:

    Domain formation in lipid bilayer membranes can occur through electrostatic interactions between charged lipids and oppositely charged polyelectrolytes, such as proteins or polynucleic acids. This review describes a novel method for examining such domains in lipid bilayers, based on 2H NMR spectroscopy. The 2H NMR Spectrum of choline-deuterated phosphatidylcholine is sensitive to, and reports on, lipid bilayer surface charge. When a charged lipid bilayer is exposed to an oppositely charged polyelectrolyte, the latter binds electrostatically to the bilayer surface and attracts charged lipids into its vicinity. The resulting inhomogeneous charge distribution produces overlapping 2H NMR subspectra arising from phosphatidylcholine within charge-enriched versus charge-depleted regions. Such spectral details as the quadrupolar splittings and the relative intensities of the subspectra permit a complete analysis of the domain composition, size, and, within limits, lifetime. Using 2H NMR, domain formation in lipid bilayer membranes can be observed with both cationic and anionic polyelectrolytes, whether of natural or synthetic origin. Domain size and composition prove to be sensitive to the detailed chemical structure of both the polyelectrolyte and the charged lipids. Within the domains there is always a stoichiometric anion/cation binding ratio, indicating that the polyelectrolyte lies flat on the membrane surface. The amount of phosphatidylcholine within the domain varies as a function of its statistical availability, in accordance with the predictions of a recent thermodynamic model of domain formation. When the molecular weight of the polyelectrolyte is varied, the domain size alters in accordance with the predictions of classical polymer physics. As expected for a predominantly electrostatic phenomenon, the observed domains dissipate at high ionic strength.

Peter M. Macdonald - One of the best experts on this subject based on the ideXlab platform.

  • Polyelectrolyte-induced domains in lipid bilayer membranes: the deuterium NMR perspective.
    Biochemistry and cell biology = Biochimie et biologie cellulaire, 1998
    Co-Authors: Peter M. Macdonald, Peter Mitrakos, Carla M. Franzin, Kevin J. Crowell, Darlene J. Semchyschyn
    Abstract:

    Domain formation in lipid bilayer membranes can occur through electrostatic interactions between charged lipids and oppositely charged polyelectrolytes, such as proteins or polynucleic acids. This review describes a novel method for examining such domains in lipid bilayers, based on 2H NMR spectroscopy. The 2H NMR Spectrum of choline-deuterated phosphatidylcholine is sensitive to, and reports on, lipid bilayer surface charge. When a charged lipid bilayer is exposed to an oppositely charged polyelectrolyte, the latter binds electrostatically to the bilayer surface and attracts charged lipids into its vicinity. The resulting inhomogeneous charge distribution produces overlapping 2H NMR subspectra arising from phosphatidylcholine within charge-enriched versus charge-depleted regions. Such spectral details as the quadrupolar splittings and the relative intensities of the subspectra permit a complete analysis of the domain composition, size, and, within limits, lifetime. Using 2H NMR, domain formation in lipid bilayer membranes can be observed with both cationic and anionic polyelectrolytes, whether of natural or synthetic origin. Domain size and composition prove to be sensitive to the detailed chemical structure of both the polyelectrolyte and the charged lipids. Within the domains there is always a stoichiometric anion/cation binding ratio, indicating that the polyelectrolyte lies flat on the membrane surface. The amount of phosphatidylcholine within the domain varies as a function of its statistical availability, in accordance with the predictions of a recent thermodynamic model of domain formation. When the molecular weight of the polyelectrolyte is varied, the domain size alters in accordance with the predictions of classical polymer physics. As expected for a predominantly electrostatic phenomenon, the observed domains dissipate at high ionic strength.

  • Detection and quantification of asymmetric lipid vesicle fusion using deuterium NMR.
    Biochemistry, 1997
    Co-Authors: Carla M. Franzin, Peter M. Macdonald
    Abstract:

    It is demonstrated that deuterium nuclear magnetic resonance (2H NMR) spectroscopy can be used to detect and to quantify fusion between anionic giant unilamellar vesicles (GUVs) and cationic small unilamellar vesicles (SUVs). The sensitivity to fusion relies on the conformational response of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) to changes in membrane surface electrostatic charge due to lipid mixing upon fusion. This conformational change is reported in the 2H NMR Spectrum as a change in the quadrupolar splitting from choline-deuterated POPC. GUVs were composed of varying molar ratios of the anionic lipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG), plus cholesterol (CHOL), plus POPC. SUVs were composed of the cationic lipid 1,2-dioleoyloxy-3-(dimethylammonio)-propane (DODAP), plus POPC with or without 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE). Using a quantitative model that relates the 2H NMR quadrupolar splitting to the mole fractions of cationic, anionic, and neutral lipids in the vesicle membrane, it was possible to deduce the extent of fusion between the two oppositely-charged vesicle populations directly from the quadrupolar splitting. SUVs composed of DODAP + POPC + POPE (40/40/20) fused 100% with GUVs composed of POPC + CHOL + POPG (60/30/10). Removing POPE from the SUVs reduced the extent of fusion, as did reducing the POPG content of the GUVs.

  • DNA-induced lateral segregation of cationic amphiphiles in lipid bilayer membranes as detected via 2H NMR.
    Biochemistry, 1996
    Co-Authors: Peter Mitrakos, Peter M. Macdonald
    Abstract:

    2H NMR spectroscopy was used to investigate the response of specifically choline-deuterated 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) to changes in surface electrostatic charge in membranes consisting of mixtures of POPC plus various cationic amphiphiles plus polyadenylic acid (polyA). Three different cationic amphiphiles were investigated:  cetyltrimethylammonium bromide (CTAB), dioleoyldimethylaminopropane (DODAP), and 3β[N-(N‘,N‘-dimethylaminoethane)carbamoyl]cholesterol (DC-CHOL). Each of the cationic amphiphiles elicited a concentration-dependent decrease (increase) in the quadrupolar splitting from POPC-α-d2 (POPC-β-d2), as expected for the accumulation of cationic charges at the surface of a lipid bilayer. However, the strength of the response varied with the cationic amphiphile in the order CTAB > DODAP > DC-CHOL. When polyA was added to the cationic amphiphile-containing lipid bilayers, the 2H NMR Spectrum consisted of two overlapping Pake patterns, indicating the presence of two li...

  • Influence of lipid lateral distribution on the surface charge response of the phosphatidylcholine headgroup as detected using 2H nuclear magnetic resonance
    Biochimica et biophysica acta, 1993
    Co-Authors: Francesca M. Marassi, Selma Djukic, Peter M. Macdonald
    Abstract:

    The effect of lipid lateral distribution on the surface charge response of the phosphatidylcholine headgroup, in bilayers composed of binary mixtures of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1,2-dimyristoyl-sn-glycero-3-phosphate (DMPA), was investigated by monitoring the deuterium nuclear magnetic resonance (2H-NMR) Spectrum of choline-deuterated phosphatidylcholine as a function of temperature and DMPA concentration. Addition of DMPA at temperatures corresponding to fully liquid-crystalline membranes caused a progressive increase (decrease) in the 2H-NMR quadrupole splitting from POPC-alpha-d2 (POPC-beta-d2), in agreement with the known response of phosphatidylcholine to negative membrane surface charge (Seelig, J., Macdonald, P.M. and Scherer, P.G. (1987) Biochemistry 26, 7535-7541). Lateral phase separation of DMPA-rich domains was induced in these mixtures by lowering the temperature in the range from 60 degrees C to -15 degrees C, and was accompanied by a reversal of the original effects of DMPA on the quadrupole splitting. Analysis of the 2H-NMR spectral response allows one to generate a temperature/composition phase diagram for the POPC/DMPA system. We conclude that 2H-NMR of headgroup-deuterated phosphatidylcholine can be employed to sense and to quantify inhomogeneities in the lateral distribution of charged membrane components.