The 18-crown-6.2 chloroacetonitrile complex. X-ray crystal structure and solid phase motions of guest and host as studied by variable temperature 13C CPMAS NMR spectroscopy

The title complex has two distinct 18-crown-6 moieties of approximate D3d symmetry in the unit cell. The 45.3 MHz 13C CPMAS spectra have two regions of broadening for the crown ether carbons. At high temperatures a dipolar washout mechanism is operative, leading to broadening when molecular motion has a correlation time approximately equal to the inverse of the decoupling field. At lower temperatures broadening occurs when the motional correlation time is equal to the inverse of the chemical shift difference. The activation energy for 18-crown-6 reorientation in this solid is calculated to be ca. 48 kJ/mol. For the chloroacetonitrile, the CH2 carbon also shows dipolar washout, but at a temperature much lower than the 18-crown-6. The activation energy for reorientation for this "guest species" is ca. 42 kJ/mol.

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A novel 1:1 benzenesulfonamide: 18-crown-6 complex as uncovered via 13C solid phase NMR spectroscopy and X-ray crystallography

Canadian Journal of Chemistry ◽

10.1139/v89-183 ◽

1989 ◽

Vol 67 (7) ◽

pp. 1212-1218 ◽

Cited By ~ 10

Author(s):

G. W. Buchanan ◽

C. Morat ◽

J. P. Charland ◽

C. I. Ratcliffe ◽

J. A. Ripmeester

Keyword(s):

Crown Ether ◽

Correlation Time ◽

Molecular Motion ◽

Solid Phase ◽

Crystallographic Structure ◽

Temperature Dependent ◽

X Ray ◽

X Ray Crystallography ◽

Anisotropic Motion ◽

Motional Correlation Time

A 1:1 complex of 18-crown-6 ether and benzenesulfonamide has been prepared, whose melting point is within 4° of the previously reported 1:2 complex. The X-ray crystallographic structure shows pseudo D3d symmetry in the crown ether portion of this complex, in contrast to the 1:2 complex, which exhibits Ci symmetry in the macrocycle. The temperature dependent 13C CPMAS NMR spectra of these complexes have two regions of broadening for the crown ether carbons. At higher temperatures, a dipolar "washout" mechanism is operative, leading to broadening when molecular motion has a correlation time approximately equal to the inverse of the decoupling field. At lower temperatures broadening occurs when the motional correlation time is equal to the inverse of the chemical shift difference. From application of the Arrhenius equation, the activation energy for the molecular motion in solid 18-crown-6 is found to be approximately 10kcal/mol. Evidence for independent anisotropic motion in the benzenesulfonamide moiety of the 1:1 complex is also presented. Keywords: crown ether, molecular motion, solid phase NMR.

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Synthesis and Ionic Conductivity of MAlSi3O8 (M = Li, Na, K)

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.790.9 ◽

2018 ◽

Vol 790 ◽

pp. 9-14

Author(s):

Shin Ichi Furusawa ◽

Yohei Minami

Keyword(s):

Activation Energy ◽

Ionic Conductivity ◽

Ionic Radius ◽

Ionic Conduction ◽

Solid Phase ◽

Solid Phase Reaction ◽

Phase Reaction ◽

X Ray Diffraction ◽

Crystalline Phases ◽

X Ray

MAlSi3O8 (M = Li, Na, K) was synthesized by solid-phase reaction at 1000 °C using M2CO3 (M = Li, Na, K), Al2O3, and SiO2 as the starting materials, and its ionic conduction was studied in the temperature range 475–800 K. It was confirmed from powder X-ray diffraction profiles that the crystalline phases of the prepared MAlSi3O8 were the same as those of orthoclase. Moreover, the ionic conductivity of NaAlSi3O8 was about 10 times higher than that of LiAlSi3O8 and KAlSi3O8. The activation energies for ionic conduction were estimated to be in the range of 0.70–0.77 eV, with NaAlSi3O8 exhibiting the lowest activation energy. The result suggests that the magnitude of the activation energy cannot be determined only from the ionic radius.

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THERMAL BEHAVIOR OF THE METACAOLINE-BASED MIXTURE FOR THE SYNTHESIS OF LEA ZEOLITE: THE INFLUENCE OF ULTRASONIC TREATMENT

IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA ◽

10.6060/ivkkt201962fp.5702 ◽

1970 ◽

Author(s):

A.P. Khramtsova ◽

V. Yu. Prokofev ◽

N.E. Gordina ◽

D.S. Cherednikova ◽

E.M. Konstantinova

Keyword(s):

Activation Energy ◽

Apparent Activation Energy ◽

Ultrasonic Treatment ◽

Solid Phase ◽

X Ray ◽

Sodium Aluminosilicate ◽

Temperature Ranges ◽

Pre Treatment ◽

Increasing Temperature ◽

Ray Patterns

A study of the influence of ultrasonic treatment on the kinetics of solid-phase interaction of metakaolin with the sodium hydroxide was performed.Reflections corresponding to the zeolite LTA were observed on X-ray patterns according to phase analysis before calcination at 500°C for the sample without pre-treatment.The appearance of a new phase of sodium alumosilicate (Na6Al4Si4O17) was observed with increasing temperature to 700°C.The reflections of sodium aluminosilicate (Na8Al4Si4O18) and nepheline were detected on the X-ray pattern when the temperature calcination 800°C besides to the characteristic reflections of the zeolite.Aluminosilicates were obtained by recrystallization of the zeolitepart.Also the process was accompanied by metakaolin decomposition in silica and mullite. Reflections corresponding to the zeolite was not discovered at 900°C.According to the X-ray analysis, it was found that ultrasonic treatment has no effect on the phase composition of the samples.Based on these data, it was determined the temperature range (500-800°C).There was recrystallization of zeolite in aluminosilicates for this temperature range.According to the thermal analysis, especially the data of mass loss in a given temperature interval, the exact temperature ranges were established for each heating rate of the samples without pre-treatment and the samples after ultrasonic treatment. The Ozawa-Flynn-Wall method was selected as an isoconversional analysis.The monotonous growth of apparent activation energy was found in all range of conversion extents after ultrasonic treatment. It smoothes the change of the transition regime (up to 200 kJ/mol) to kinetic one.The apparent activation energy for the sample without ultrasonic treatment gone approximately at one level (350 kJ/mol) upon reaching the conversion extent of 0.5-0.6.The apparent activation energy increases after ultrasonic treatment from 350 to 450 kJ/mol upon reaching the conversion extent above 0.9.

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An example of conformational disorder in solids: X-ray crystallographic and 13C CPMAS NMR studies of dibenzo and dicyclohexano-13-crown-4 ethers and some lithium complexes

Canadian Journal of Chemistry ◽

10.1139/v90-011 ◽

1990 ◽

Vol 68 (1) ◽

pp. 49-58 ◽

Cited By ~ 7

Author(s):

G. W. Buchanan ◽

R. A. Kirby ◽

J. P. Charland

Keyword(s):

Crystal Structure ◽

Crown Ethers ◽

Nmr Spectra ◽

Solid Phase ◽

Nmr Studies ◽

13C Cpmas Nmr ◽

Conformational Disorder ◽

X Ray ◽

Lithium Complexes ◽

Cis Isomer

For the cis–anti–cis isomer of dicyclohexano-13-crown-4 ether, disorder has been detected in the crystal structure, with two conformations being present in the ratio of ca. 3:2. Crystal structures for two Li+ complexes of the cis–syn–cis isomer have also been determined. Representative 13C solid phase NMR spectra are presented and discussed for these systems and the related dibenzo substituted compounds. Keywords: crown ethers, solids, NMR, conformation.

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A structural study of pyrazole-1-carboxamides by X-ray crystallography and 13C CPMAS NMR spectroscopy

Journal of Molecular Structure ◽

10.1016/s0022-2860(98)00658-9 ◽

1999 ◽

Vol 478 (1-3) ◽

pp. 81-91 ◽

Cited By ~ 4

Author(s):

Antonio L Llamas-Saiz ◽

Concepción Foces-Foces ◽

Isabel Sobrados ◽

Nadine Jagerovic ◽

José Elguero

Keyword(s):

Nmr Spectroscopy ◽

Structural Study ◽

13C Cpmas Nmr ◽

X Ray ◽

X Ray Crystallography ◽

13C Cpmas Nmr Spectroscopy

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A multinuclear solid-state magnetic resonance study of silver nitrate triphenylphosphine

Canadian Journal of Chemistry ◽

10.1139/v05-174 ◽

2005 ◽

Vol 83 (10) ◽

pp. 1721-1730 ◽

Cited By ~ 4

Author(s):

Se-Woung Oh ◽

Guy M Bernard ◽

Roderick E Wasylishen ◽

Robert McDonald ◽

Michael J Ferguson

Keyword(s):

Phase Transition ◽

Solid State ◽

Single Crystal ◽

Silver Nitrate ◽

Solid Phase ◽

Variable Temperature ◽

Spin Coupling ◽

X Ray Diffraction ◽

X Ray ◽

H Nmr

Variable-temperature solid-state 31P, 15N, and 2H NMR spectroscopy, X-ray diffraction, and differential scanning calorimetry studies of the 1:1 adduct of silver nitrate and triphenylphosphine (AgNO3·PPh3) reveal a solidsolid phase transition at 300 K. The principal components of the phosphorus and nitrogen chemical shift tensors for both phases are determined from NMR spectra of MAS and stationary samples. In addition, the indirect spin-spin coupling between phosphorus and the naturally occurring isotopes of silver (107Ag and 109Ag) are resolved. Experimental 2H NMR line shapes for silver nitrate perdeuterated triphenylphosphine are those characteristic of rigid phenyl groups at temperatures above and below the phase-transition temperature. Powder and single-crystal X-ray diffraction data for AgNO3·PPh3 obtained at 193, 295, and 313 K are reported; data obtained at 193 and 295 K are almost identical, but are significantly different from those obtained at 313 K and from an earlier single-crystal X-ray diffraction investigation performed at 298 K. All X-ray studies found that AgNO3·PPh3 crystallizes in the monoclinic form, space group P21/c.Key words: 1:1 silver nitrate triphenylphosphine adduct, solid-state NMR, X-ray diffraction, phase transition.

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Proton NMR Study of Molecular Motions in the Solid Phase of a Smectic A Liquid Crystal

Canadian Journal of Physics ◽

10.1139/p75-209 ◽

1975 ◽

Vol 53 (17) ◽

pp. 1646-1650 ◽

Cited By ~ 2

Author(s):

Ronald Y. Dong ◽

M. Wiszniewska ◽

E. Tomchuk ◽

E. Bock

Keyword(s):

Activation Energy ◽

Liquid Crystal ◽

Molecular Motion ◽

Solid Phase ◽

Methyl Groups ◽

Molecular Motions ◽

Kcal Mole ◽

Self Diffusion ◽

Smectic A ◽

Nmr Study

Proton T1, T1ρ, and T1D were studied in the solid phase of diethylazoxybenzoate from 105 K to the melting point. The activation energies for the threefold reorientation of methyl groups and for the molecular self-diffusion were determined to be about 3.3 and 11 kcal/mole respectively. Between 170 and 240 K, a new slow molecular motion with an estimated activation energy of 3.7 kcal/mole was detected via the T1ρ data.

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THERMAL BEHAVIOR OF MIXTURE BASED ON METAKAOLIN FOR LTA ZEOLITE SYNTHE-SIS: EFFECT OF ULTRASONIC TREATMENT

IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA ◽

10.6060/ivkkt.20196202.5702 ◽

2019 ◽

Vol 62 (2) ◽

pp. 65-71

Author(s):

Aleksandra P. Khramtsova ◽

Valery Yu. Prokof’ev ◽

Natalya E. Gordina ◽

Darya S. Cherednikova ◽

Ekaterina M. Konstantinova

Keyword(s):

Activation Energy ◽

Apparent Activation Energy ◽

Ultrasonic Treatment ◽

Solid Phase ◽

Conversion Degree ◽

X Ray ◽

Temperature Range ◽

Sodium Aluminosilicate ◽

Lta Zeolite ◽

Pre Treatment

A study of the influence of ultrasonic treatment on the kinetics of solid-phase interaction of metakaolin with the sodium hydroxide was performed. Reflections corresponding to the zeolite LTA were observed on X-ray patterns according to phase analysis before calcination at 500 °C for the sample without pre-treatment. The appearance of a new phase of sodium alumosilicate (Na6Al4Si4O17) was observed with increasing temperature to 700 °C. The reflections of sodium aluminosilicate (Na8Al4Si4O18) and nepheline were detected on the X-ray pattern when the temperature calcination 800 °C besides to the characteristic reflections of the zeolite. Aluminosilicates were obtained by recrystallization of the zeolite partisles. Also the process was accompanied by metakaolin decomposition in silica and mullite. Reflections corresponding to the zeolite was not discovered at 900 °C. According to the X-ray analysis, it was found that ultrasonic treatment has no effect on the phase composition of the samples. Based on these data, it was determined the temperature range (500-800 °C). There was recrystallization of zeolite in aluminosilicates for this temperature range. According to the thermal analysis, especially the data of mass loss in a given temperature interval, the exact temperature ranges were established for each heating rate of the samples without pre-treatment and the samples after ultrasonic treatment. The Ozawa-Flynn-Wall method was selected as an isoconversional analysis. The monotonous growth of apparent activation energy was found in all range of conversion degrees after ultrasonic treatment. This allows smoothing the change in the transitional regime (up to 200 kJ / mol) to kinetic one. The apparent activation energy for the sample without ultrasonic treatment gone approximately at one level (350 kJ/mol) upon reaching the conversion degree of 0.5-0.6. The apparent activation energy increases after ultrasonic treatment from 350 to 450 kJ/mol upon reaching the conversion degree above 0.9.

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Impact of Rutile Fraction on TiO2 Visible-Light Absorption and Visible-Light-Induced Photocatalytic Activity

10.26434/chemrxiv.7461161.v1 ◽

2018 ◽

Cited By ~ 1

Author(s):

David Maria Tobaldi ◽

Luc Lajaunie ◽

ana caetano ◽

nejc rozman ◽

Maria Paula Seabra ◽

...

Keyword(s):

Photocatalytic Activity ◽

Visible Light ◽

Light Absorption ◽

Solid Phase ◽

Diffraction Method ◽

Band Alignment ◽

Quantitative Phase Analysis ◽

Transmission Microscopy ◽

Visible Light Absorption ◽

X Ray

<div>Titanium dioxide is by far the most utilised semiconductor material for photocatalytic applications. Still, it is transparent to visible-light. Recently, it has been proved that a type-II band alignment for the rutile−anatase mixture would improve its visible-light absorption.</div><div>In this research paper we thoroughly characterised the real crystalline and amorphous phases of synthesised titanias – thermally treated at different temperatures to get distinct ratios of anatase-rutile-amorphous fraction – as well as that of three commercially available photocatalytic nano-TiO2. </div><div>The structural characterisation was done via advanced X-ray diffraction method, namely the Rietveld-RIR method, to attain a full quantitative phase analysis of the specimens. The microstructure was also investigated via an advanced X-ray method, the whole powder pattern modelling. These methods were validated combining advanced aberration-corrected scanning transmission microscopy and high-resolution electron energy-loss spectroscopy. The photocatalytic activity was assessed in the liquid- and gas-solid phase (employing rhodamine B and 4-chlorophenol, and isopropanol, respectively, as the organic substances to degrade) using a light source irradiating exclusively in the visible-range.</div><div>Optical spectroscopy showed that even a small fraction of rutile (2 wt%) is able to shift to lower energies the apparent optical band gap of an anatase-rutile mixed phase. But is this enough to attain a real photocatalytic activity promoted by merely visible-light?</div><div>We tried to give a reply to that question.</div><div>Photocatalytic activity results in the liquid-solid phase showed that a high surface hydroxylation led to specimen with superior visible light-induced catalytic activity (i.e. dye and ligand-to-metal charge transfer complexes sensitisation effects). That is: not photocatalysis <i>sensu-strictu</i>.</div><div>On the other hand, the gas-solid phase results showed that a higher amount of the rutile fraction (around 10 wt%), together with less recombination of the charge carriers, were more effective for an actual photocatalytic oxidation of isopropanol.</div>

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