A Highly Disordered New Solid Phase Containing Isotropically Reorienting Cations in (CH3NH3 )2CdBr4 Studied by 1H NMR and Thermal Measurements

1990 ◽  
Vol 45 (9-10) ◽  
pp. 1190-1192 ◽  
Author(s):  
Hiroyuki Ishida ◽  
Kentaro Takagi ◽  
Mifune Terashima ◽  
Daiyu Nakamura
Keyword(s):  
Room Temperature ◽  
Solid Phase ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Temperature Phase ◽  
Scanning Calorimetry ◽  
Spin Lattice ◽  
H Nmr ◽  
Thermal Measurements

Abstract The 1H spin-lattice relaxation time, linewidth, second moment of 1H NMR absorption, differen-tial thermal analysis, and differential scanning calorimetry of methylammonium tetrabromocado-mate(II) crystals were studied. A new solid phase was found between 482 K and the melting point (493 K). The 1H NMR measurements revealed the presence of overall reorientation of methyl-ammonium cations in this phase. In the room temperature phase, 120° reorientational jumps of the CH3 and NH3+ groups were detected.

Motions of Methylammonium Ions in (CH3NH3)2ZnBr4 Crystals Studied by 1H NMR and Thermal Measurements

1990 ◽  
Vol 45 (7) ◽  
pp. 923-927
Author(s):  
Hiroyuki Ishida ◽  
Kentaro Takagi ◽  
Tadashi Iwachido
Keyword(s):  
Solid Phase ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
High Temperature Phase ◽  
Spin Lattice Relaxation ◽  
Temperature Phase ◽  
Scanning Calorimetry ◽  
Self Diffusion ◽  
Spin Lattice ◽  
H Nmr

AbstractMeasurements of the 1H spin-lattice relaxation time T1, the linewidth parameter T*2the second moment of 1H NMR absorption, differential thermal analysis, and differential scanning calorimetry were performed on methylammonium tetrabromozincate(II) crystals from 58 to above 500 K. A solid-solid phase transition was located at 456 K. In the room temperature phase, 120° reorientational jumps of CH3 and NH3+ groups in the cation about its C -N bond axis were detected. In the high-temperature phase, the cations undergo overall reorientation as well as translational self-diffusion. The activation energy for the cationic self-diffusion was evaluated to be 18 kJ mol-1 .

scholarly journals Cationic Dynamics in the Crystalline Phases of (CH3NH3)PbX3 (X: Cl, Br) as Studied by Proton Magnetic Resonance Techniques

1989 ◽  
Vol 44 (11) ◽  
pp. 1122-1126 ◽  
Author(s):  
Yoshihiro Furukawa ◽  
Daiyu Nakamura
Keyword(s):  
Room Temperature ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Anomalous Behavior ◽  
Spin Lattice Relaxation ◽  
Rotational Relaxation ◽  
Temperature Phase ◽  
Spin Lattice ◽  
H Nmr ◽  
Temperature Dependences

The temperature dependences of the 1H spin-lattice relaxation time T1, the linewidth parameter T2*. and the second moment M2 of 1H NMR absorption were measured for solid (CH3NH3)PbX3 (X: CI. Br). In the room-temperature cubic phases of both salts, and also in the high-temperature tetragonal phase of (CH3NH3)PbBr3, the cations undergo rapid overall rotation or reorientation. In the lowest-temperature phase of both salts the orientation of the cations is fixed but rapid C3 reorientation of the CH3 and NH+3 groups of the cations about their C - N bond axes takes place. From the M2 measurements, a precessional motion of the cations in the intermediate-temperature phase of both complexes is suggested. Above room temperature, 1H T1 of both salts can be explained by assuming spin-rotational relaxation operative due to the rapid rotation of the cations. An anomalous behavior of 1H T1, attributable to cross relaxation between 1H and 81Br nuclei, was detected for (CH3NH3) PbBr3 when T1 was measured at 42 MHz

H NMR Study of Ionic Motions in High Temperature Solid Phases of (CH3NH3)2ZnCl4

2000 ◽  
Vol 55 (3-4) ◽  
pp. 412-414 ◽  
Author(s):  
Hiroyuki Ishida
Keyword(s):  
Activation Energy ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
The Self ◽  
Spin Lattice Relaxation ◽  
Temperature Phase ◽  
Self Diffusion ◽  
Spin Lattice ◽  
H Nmr ◽  
Nmr Study

Abstract The reorientation of the tetrahedral complex anion ZnCl42- and the self-diffusion of the cation in (CH3NH3)2ZnCl4 were studied by 1H NMR spin-lattice relaxation time (1H T1) experiments. In the second highest-temperature phase, the temperature dependence of 1H T1 observed at 8.5 MHz could be explained by a magnetic dipolar-electric quadrupolar cross relaxation between 1H and chlorine nuclei, and the activation energy of the anion motion was determined to be 105 kJ mol -1 . In the highest-temperature phase, the activation energy of the self-diffusion of the cation was determined to be 58 kJ mol -1 from the temperature and frequency dependence of 1H T1

Self-Diffusion and Reorientation of Methylammonium Ions in (CH3NH3)2ZnCl4 Crystals as Studied by 1H-NMR

1989 ◽  
Vol 44 (8) ◽  
pp. 741-746 ◽  
Author(s):  
Hiroyuki Ishida ◽  
Tadashi Iwachido ◽  
Naomi Hayama ◽  
Ryuichi Ikeda ◽  
Mifune Terashima ◽  
...  
Keyword(s):  
Solid Phase ◽  
Relaxation Times ◽  
Three Dimensional ◽  
Lattice Relaxation ◽  
High Temperature Phase ◽  
Spin Lattice Relaxation ◽  
Temperature Phase ◽  
Scanning Calorimetry ◽  
Self Diffusion ◽  
H Nmr

Abstract Differential thermal analysis, differential scanning calorimetry, and measurements of the 1H spin-lattice relaxation times and second moments of 1H-NMR absorptions were performed on methylammonium tetrachlorozincate (II) crystals over a wide temperature range. A solid-solid phase transition was located at 477 K. From the 1H-NMR experiments it was found that the cations undergo overall reorientation as well as three dimensional translational self-diffusion in the high-temperature phase. In the low-temperature phase, a 120° reorientational motion of the CH3 and NH3+ groups of the cation about its C-N bond axis was detected. The parameters for the motional modes of the cations in the crystal were evaluated from the analysis of the 1H-NMR experimental results.

Structural Phase Transitions and Ionic Motions in Pyridinium Hexachlorotellurate(IV),Hexachlorostannate(IV), and Hexabromostannate(IV) Crystals as Studied by 1H NMR

1989 ◽  
Vol 44 (4) ◽  
pp. 300-306 ◽  
Author(s):  
Yutaka Tai ◽  
Tetsuo Asaji ◽  
Ryuichi Ikeda ◽  
Daiyu Nakamura
Keyword(s):  
Phase Transitions ◽  
High Temperature ◽  
Structural Phase ◽  
Lattice Relaxation ◽  
Relaxation Mechanism ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Scanning Calorimetry ◽  
Spin Lattice ◽  
H Nmr

Abstract The 1H NMR second moment M2 and the spin-lattice relaxation time T1 are determined for pyridinium hexachlorotellurate(IV), hexachlorostannate(IV), and hexabromostannate(IV) at various temperatures above ca. 140 K. The phase transition temperatures already reported from halogen NQR experiments are determined as 272, 331, and 285 K, respectively, by differential thermal analysis (DTA). The DTA as well as differential scanning calorimetry measurements show that the above phase transitions are of second-order. For pyridinium hexachlorotellurate(IV) and hexa-bromostannate(I V), a sharp 1H T1 dip was observed at the transition temperature. This is interpreted in terms of a phenomenon related to the critical fluctuation of an order parameter. From the measurements of 1H M2, 60° two-site jumps (60° flips) around the pseudo C6 axis of the cation are suggested to occur in the high temperature phases of the complexes. Modulation of X...1H (X = CI, Br) magnetic dipolar interactions due to the reorientational motion of the complex anions is considered as a possible relaxation mechanism in the high temperature phases.

2H NMR Study of Molecular and Electron Spin Dynamics in Paramagnetic [Co(H2O)6][SiF6]

2000 ◽  
Vol 55 (1-2) ◽  
pp. 173-177
Author(s):  
Takahiro Iijima ◽  
Motohiro Mizuno ◽  
Masahiko Suhara
Keyword(s):  
Water Molecule ◽  
Room Temperature ◽  
Spin Dynamics ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Spectral Simulation ◽  
Spin Lattice ◽  
H Nmr ◽  
Nmr Study

The temperature dependences of 2H NMR spectra and the spin-lattice relaxation time T\ were measured for [Co(H2O)f,][SiF6]. The variation of the spectrum above room temperature can be explained by the reorientation of [Co(H2O)6]2+ about the C3 axis. The activation energy Ea and the jumping rate at infinite temperature K0 for the three site jump of [Co(H2O)6]2+ were obtained as 82 kJmol-1 and 2x 1017s-1 from the spectral simulation. Below room temperature, the spectral line shape was dominated by the 180° flip of the water molecule. The minimum of T1 caused by the 180° flip of the water molecule was observed at ca. 260 K. The jumping rate of the 180° flip of the water molecule was estimated from the 2H NMR T1 and the spectral simulation. Ea = 38 kJmol-1 and K0 = 6x 1015s-1 for the 180° flip of the water molecule were obtained from T1.

An 1H NMR Study on the Cationic Motion in Solid tert-Butylammonium Chloride and Bromide

1991 ◽  
Vol 46 (3) ◽  
pp. 265-268 ◽  
Author(s):  
Hiroyuki Ishida ◽  
Syuichi Inada ◽  
Naomi Hayama ◽  
Daiyu Nakamura ◽  
Ryuichi Ikeda
Keyword(s):  
Relaxation Time ◽  
1H Nmr ◽  
Room Temperature ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
X Ray ◽  
Spin Lattice ◽  
H Nmr ◽  
Nmr Study

AbstractThe 1H spin-lattice relaxation time (T1) in solid (CD3)3CNH3Cl and (CD3)3CNH3Br was measured above room temperature and the motional parameters for the reorientation of the NH3+ groups were determined. The 1H NMR absorptions measured in the same temperature range for (CH3)3CNH3Cl and (CH3)3CNH3Br indicate the presence of superimposed several cationic motions commonly taking place in both compounds. From X-ray powder patterns taken at room temperature, the bromide was found to be isomorphous with the chloride

scholarly journals 1H NMR and Differential Scanning Calorimetry Studies of Molecular Motion and Phase Transition in Butylammonium Iodide

1985 ◽  
Vol 40 (4) ◽  
pp. 347-354
Author(s):  
Shin-ichi Fukada ◽  
Ryuichi Ikeda ◽  
Daiyu Nakamura
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Solid Phase ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Temperature Phase ◽  
Scanning Calorimetry ◽  
H Nmr ◽  
Wide Range

The temperature variations of 1H NMR spin-lattice relaxation times and 1H NMR second moments in n-C4H9NH3I and its N-deuterated analog were studied in a wide range of temperatures above 77 K. DTA experiments revealed a solid-solid phase transition between room and low temperature phases taking place at 268 K for the former salt and at 267 K for the latter. For rapidly cooled ( ≳ 2 Kmin-1 ) samples, another phase transition possibly between substable low temperature phases was found at ca. 210 K for the former and ca. 205 K for the latter. The transition entropy observed at 268 K was 33 J K-1 mol-1. This is much larger than the melting entropy (16 J K-1 mol-1), suggesting that butylammonium ions obtain their motional freedom mostly at the phase transition. In the low temperature phase of n-C4H9NH3I, the CH3 and NH3+ groups perform C3 reorientation about their respective symmetry axes with the activation energies 10.4 and 26.8kJmol-1, respectively. The rapidly cooled sample showed two T1 components attributable to the stable and substable low temperature phases indicating the coexistence of both phases. In the room temperature phase, the cations rotate rapidly about their long axes and partly conformational disorder of the alkyl chains takes place. The mechanism of the phase transitions is discussed.

1H and 19 F NMR Studies on Molecular Motions in Two Solid Phases of t-Butylammonium Tetrafluoroborate

1998 ◽  
Vol 53 (9) ◽  
pp. 796-800 ◽  
Author(s):  
Hiroyuki Ishida
Keyword(s):  
Solid Phase ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Scanning Calorimetry ◽  
Nmr Studies ◽  
Spin Lattice ◽  
Solid Phases ◽  
Solid Phase Transition ◽  
19 F Nmr

Abstract Differential thermal analysis (DTA), differential scanning calorimetry (DSC), and the temperature dependence of the spin-lattice relaxation time (T1) and the second moment (M2) of 1H and 19F NMR were studied in (CH3)3CNH3BF4 and (CH3)3CND3BF4 . DTA and DSC revealed a solid-solid phase transition at 219 K for (CH3)3CNH3BF4 and at 221 K for (CH3)3CND3BF4 . The motions of cations and anions in the two solid phases were studied by T1 and M2 experiments. The motional modes of the ions and their motional parameters were determined.

Molecular motion in crown ethers. Application of 13C and 2H NMR to the study of 4-carboxybenzo-24-crown-8 ether and its KNCS complex in solution and in the solid phase

1996 ◽  
Vol 74 (8) ◽  
pp. 1437-1446 ◽  
Author(s):  
G.W. Buchanan ◽  
A. Moghimi ◽  
C.I. Ratcliffe
Keyword(s):  
Molecular Motion ◽  
Solid Phase ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Scanning Calorimetry ◽  
Phase Dynamics ◽  
Spin Lattice ◽  
H Nmr ◽  
Macrocyclic Ethers

Large-amplitude solid phase molecular motion has been detected in the macrocyclic ring of the title crown either via 13C CPMAS NMR. To study the details of the dynamic processes, two selectively deuterated d4 derivatives have been prepared and examined via 2H NMR as a function of temperature. A phase change occurring around 277 K has been verified by differential scanning calorimetry (DSC) and a model for the motional processes has been developed involving equivalent two-site flips of the CD2 groups. The amplitude of the CD2 motions apparently decreases the closer the group is to the aromatic ring. The influence of KNCS complexation on the 13C CPMAS spectrum and on 13C spin lattice relaxation times in solution has been explored. Key words: macrocyclic ethers, solid phase dynamics.

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