Rotational isomerism of the tetraethylammonium cation in solution and in the solid state

Naudin, C.; Bonhomme, Frédéric; Bruneel, Jean‐Luc; Ducasse, Laurent; Grondin, Joseph; Lassègues, J.C.; Servant, Laurent

doi:10.1002/1097-4555(200011)31:11<979::aid-jrs629>3.0.co;2-y

Cited by 52 publications

(38 citation statements)

References 30 publications

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“…10 %. The interconversion energy difference in solution between the two conformers is Δ E tg.tg ‐ tt.tt =4.1 kJ (mol TEA + ) −1 , and higher concentrations are known to lead to a greater proportion of the tg.tg conformer due to its lower volume …”

Section: Figuresupporting

confidence: 92%

“…Raman spectra of the TEA + salts are shown in Figure a, and the crystalline TEABr shows only the tt.tt conformer, while crystalline TEAF dihydrate and TEAOH solution both contain a distribution of conformers. The temperature‐dependent conformer distribution of TEAOH in solution is shown in Figure c, the tt.tt conformer dominates at lower temperatures, and the conformer distribution becomes nearly equal as temperature increases, with an overall variation in the conformer ratio of ca.…”

Section: Figuresupporting

confidence: 91%

“…Tetraethylammonium (TEA + ), a common OSDA, is among the simplest quaternary ammonium molecules, and its pore‐filling role is evident from the number of frameworks it is known to form: AEI, AFI, BEA, CHA, LTA, MFI, MOR, and UFI . TEA + is known to exist in two distinct conformations, designated as tt.tt and tg.tg , which can be easily distinguished using Raman spectroscopy, highlighted in Figure . Crystalline TEA + salts exist as single conformers, but in solution display a temperature, pressure and concentration dependent conformer equilibrium .…”

Section: Figurementioning

confidence: 99%

“…TEA + is known to exist in two distinct conformations, designated as tt.tt and tg.tg , which can be easily distinguished using Raman spectroscopy, highlighted in Figure . Crystalline TEA + salts exist as single conformers, but in solution display a temperature, pressure and concentration dependent conformer equilibrium . When occluded in MMs, TEA + has been shown to exist predominantly as a single conformer in AFI ( tt.tt primarily), BEA ( tt.tt exclusively), and CHA ( tg.tg primarily) .…”

Section: Figurementioning

confidence: 99%

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Template–Framework Interactions in Tetraethylammonium‐Directed Zeolite Synthesis

Schmidt

Deem

et al. 2016

Angewandte Chemie

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Zeolites,having widespread applications in chemical industries,are often synthesized using organic templates.These can be cost-prohibitive,motivating investigations into their role in promoting crystallization. Herein, the relationship between framework structure,c hemical composition, synthesis conditions and the conformation of the occluded, economical template tetraethylammonium (TEA + )has been systematically examined by experimental and computational means.T he results show two distinct regimes of occluded conformer tendencies:1 )Inf rameworks with al arge stabilization energy difference,o nly as ingle conformer was found (BEA, LTAa nd MFI). 2) In the frameworks with small stabilization energy differences (AEI, AFI, CHA and MOR), less than the interconversion of TEA + in solution, aheteroatom-dependent (Al, B, Co,M n, Ti,Z n) distribution of conformers was observed. These findings demonstrate that host-guest chemistry principles,i ncluding electrostatic interactions and coordination chemistry,are as important as ideal pore-filling.Microporous materials (MMs) are crystalline solids that contain pores of less than 2nm, and find applications ranging from separations and ion exchange to catalysis (zeolites are aluminosilicate MMs).[1, 2] Although over 230 frameworks are known, economic considerations,o fw hich the cost of the organic templates,r eferred to as organic structure-directing agents (OSDAs), dominate,m ean only ah andful are commercial, even though others could offer superior performance in agiven application. [3][4][5] This has inspired investigations into the complex processes governing the crystallization of MMs, with the goal of supplanting the use of expensive organics.

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Section: Figuresupporting

confidence: 92%

Section: Figuresupporting

confidence: 91%

Section: Figurementioning

confidence: 99%

Section: Figurementioning

confidence: 99%

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Template–Framework Interactions in Tetraethylammonium‐Directed Zeolite Synthesis

Schmidt

Deem

et al. 2016

Angewandte Chemie

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“…As TEA cations appear predominantly in two conformer states [25] it was necessary to find out the prevailent conformer state in the studied compound. As in the PS analogue, the results from Raman spectroscopy show only the presence of one conformer state tt.tt conformer (C4N stretching at 676 cm −1 , Fig.…”

Section: Insert Figmentioning

confidence: 99%

Structural investigations in pure-silica and Al-ZSM-12 with MTEA or TEA cations

Počkaj

Meden

Logar

et al. 2018

Microporous and Mesoporous Materials

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Two different quaternary ammonium cations, methyltriethyl-(MTEA) and tetraethylammonium cations (TEA) were used as templates in the synthesis of puresilica as well as aluminosilicate ZSM-12 (MTW-type) frameworks. The distribution of the template cations in the 12MR channels in the 1-dimensional framework topology was studied; thus the as-prepared products were characterized by means of X-ray powder diffraction, Raman, transmission FTIR, solid-state NMR spectroscopy, thermogravimetric and elemental analyses and SEM. Recently, it was shown that in pure-silica (PS) ZSM-12, TEA cations are well ordered-a superstructure with threetimes longer b edge along the channel is formed, which can be seen by virtue of a few additional peaks in the X-ray powder pattern. Herein we describe that its aluminosilicate counterpart with TEA also contains ordered TEA cations and is isostructural to PS-ZSM-12. Conversely, in both pure-silica and aluminosilicate ZSM-12 frameworks with MTEA, the cations are disordered and no superstructure is formed.

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An Alternative Ionic Conductivity Mechanism for Plastic Crystalline Salt–Lithium Salt Electrolyte Mixtures

Henderson

Seo

Zhou

et al. 2012

Advanced Energy Materials

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Often, these transitions are associated with the formation of highly disordered solid crystalline phases which retain the long-range order of the ion packing, but on a local level the ions have considerable conformational and rotational motion. Doping such salts with small amounts of a lithium salt has been demonstrated to markedly increase the ionic conductivity of the mixtures. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] It was suggested that the explanation for this may be the creation of defects in the lattice of the plastic crystalline salt and corresponding tremendous improvement in solid-state diffusion/conduction. In the present work, we suggest that the observed increase in conductivity by several orders of magnitude upon doping the salt with small quantities of lithium salt may be attributable to an entirely different origin. Plastic crystalline salts and ionic liquids (ILs-salts with a low melting point) are often structurally similar materials. The phase behavior and ionic conductivity of mixtures consisting of N -alkyl-N -methylpyrroldinium and 1-alkyl-3-methylimidazolium bis(trifl uoromethanesulfonyl)imide (PYR 1R TFSI and IM 10R TFSI) salts with LiTFSI have previously been examined. [ 9 , 20-22 ] The TFSI − anion, N(SO 2 CF 3 ) 2 − , has extensive negative charge delocalization and fl exibility-properties which The phase behavior and ionic conductivity of tetraethylammonium bis(trifl uoromethane-sulfonyl)imide (Et 4 NTFSI) salt mixtures with LiTFSI have been examined. In addition, the phase behavior and crystal structure of neat LiTFSI is also reported. Two (1− x ) Et 4 NTFSI-( x ) LiTFSI ( x = 0.50 and 0.67, where x is the mol fraction) mixed-salt crystalline phases form. Large variations in ionic conductivity are observed; these are attributed to solidsolid phase transitions of the neat Et 4 NTFSI salt creating disordered plastic crystalline phases and the formation of a low-melting eutectic composition between the neat Et 4 NTFSI salt and the 1/1 Et 4 NTFSI/LiTFSI ( x = 0.50) phase.Although Et 4 NTFSI and LiTFSI melt at 102 and 234 ° C, respectively, the two salts form a eutectic system with a melting temperature of 32 ° C. Based upon the fi ndings reported, a new conductivity mechanism is proposed for plastic crystalline salt-lithium salt electrolytes which is not ascribed to solid-state diffusion/conduction.

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Rotational isomerism of the tetraethylammonium cation in solution and in the solid state

Cited by 52 publications

References 30 publications

Template–Framework Interactions in Tetraethylammonium‐Directed Zeolite Synthesis

Template–Framework Interactions in Tetraethylammonium‐Directed Zeolite Synthesis

Structural investigations in pure-silica and Al-ZSM-12 with MTEA or TEA cations

An Alternative Ionic Conductivity Mechanism for Plastic Crystalline Salt–Lithium Salt Electrolyte Mixtures

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