Probing the pore space in mesoporous materials by laser enhanced hyperpolarised 129Xe NMR

Guenneau, Flavien; Nader, M.; Salamé, Pétra; Launay, Franck; Semmer-Herlédan, V.; Gédéon, A.

doi:10.1016/j.cattod.2005.11.069

Cited by 8 publications

(8 citation statements)

References 28 publications

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“…Organically modified mesoporous silica phases have attracted much attention in the field of adsorption, chemical sensing, and catalysis. , Among the enormous functional variation of organic chemistry, materials bearing alkyl or arenesulfonic groups have received considerable interest in heterogeneous catalysis due to their high surface area and relatively important acid strength. − Co-condensation routes 6-9,11,12,14 are preferred over grafting procedures 10,15,16 due to the better distribution of the functions throughout the resulting materials. In most of the cases, the sulfonic acid functions are introduced by the rather unselective oxidation of mercaptopropyl groups onto silica. − Direct introduction of a stronger function by 2-(4-chlorosulfonylphenyl)ethyltrimethoxysilane (CSPTMS) is also considered with growing attention. In this work, SBA-15-type materials functionalized with different incorporation ratio 0.05 < R = (CSPTMS/CSPTMS + TEOS) < 0.20 have been prepared by the co-condensation of CSPTMS and prehydrolyzed TEOS using Pluronic 123 as a template under acidic conditions.…”

Section: Introductionmentioning

confidence: 99%

Evidence of Specific Interactions between Laser-Polarized Xenon and Arenesulfonic Acid Groups in Functionalized SBA-15 Materials

Nader¹,

Guenneau²,

Salamé³

et al. 2007

J. Phys. Chem. C

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SBA-15 samples functionalized with different arenesulfonic organic contents and prepared at 373 K were characterized by hyperpolarized 129Xe NMR spectroscopy. Variable-temperature measurements provide information on the organic groups distribution in the materials and on Xe diffusion in the mesopores. The heat of adsorption of xenon on the surface as well as its chemical shift value in interaction with the surface are deduced from the temperature dependence of the 129Xe chemical shift. The arenesulfonic group surface coverage was determined, and consequently, the “organic phase” contribution to the shielding constant was estimated. The evolution of the chemical shift with pressure allowed us to evaluate the “xenon−organic phase” interactions and hence distinguish the different organic contents. The slope of the pressure chemical shift dependence reveals the way in which the functionalization process took place. For low organic content (0.05 and 0.10), the slope is negative, indicating the presence of shallow micropores, while for high organic content (0.15 and 0.20), the chemical shift remains unchanged with the pressure showing that the modified mesoporous surface is homogeneous and micropores exempt. Information about the vicinity of Xe−organic phase are obtained from 129Xe−H CP and SPINOE experiments.

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Section: Introductionmentioning

confidence: 99%

Evidence of Specific Interactions between Laser-Polarized Xenon and Arenesulfonic Acid Groups in Functionalized SBA-15 Materials

Nader¹,

Guenneau²,

Salamé³

et al. 2007

J. Phys. Chem. C

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“…[42][43][44][45][46][47][48][49]). As part of our continuous effort to explore the porosity and the chemical properties of arenesulfonic modified mesoporous materials by spectroscopic methods [50,51], we proposed here, for the first time, an infrared study of their acidity using two basic probes of CO and NH 3 . The possibility mechanism also was discussed.…”

Section: Introductionmentioning

confidence: 99%

Infrared investigations of arenesulfonic modified mesoporous materials by the use of complementary probes

et al. 2011

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Arenesulfonic mesoporous materials [SBA(R), 0.05 B R (incorporation ratio) B0.15] have been prepared by the co-condensation of tetraethoxysilane (TEOS) and 2-(4-chlorosulfonylphenyl) ethyltrimethoxysilane (CSPTMS) in acidic solutions of Pluronic P123. The extent of the surface functionalisation and the nature of the interactions between sulfonic groups and the surface in SBA(0.05) and SBA(0.15) samples were investigated by FT-IR spectroscopy using two probes of different basic strengths. It was shown that carbon monoxide (CO, at 77 K) can be used as a good probe to study the surface functionalisation through the m C=O vibration at 2,158 cm -1 corresponding to its interaction with free silanol groups. Ammonia (NH 3 , at 423 K) is able to disturb the strong interactions of Si-OH-H 3 OS by forming the d NH -NH 4 ? which allowed to emphasise that SO 3 H groups of the less functionalised material SBA(0.05) are less acidic since the number of the acid groups is less important than in SBA(0.15).

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“…If this were the case, molecular simulation trajectories could be analyzed in terms of preparametrized NMR ''force fields'', [2][3][4][5][6] without the need to resort to computationally heavy determination of the average NMR properties via electronic structure calculation of individual simulation snapshots. [7][8][9][10][11][12][13][14][15] Xenon is particularly interesting from the point of view of the applicability of PAA, as the NMR of guest 129/131 Xe atoms is widely used to investigate the structure and dynamics of various host materials such as micro-and mesoporous solids, [16][17][18][19][20][21][22][23][24][25][26] liquids and liquid crystals, [27][28][29][30][31][32][33][34][35][36][37] and solid surfaces. [38][39][40][41] Nevertheless, even the prototypic system of xenon gas still challenges the theoretical understanding of Xe NMR.…”

Section: Introductionmentioning

confidence: 99%

Pairwise additivity in the nuclear magnetic resonance interactions of atomic xenon

Hanni

Lantto

Vaara

2009

Phys. Chem. Chem. Phys.

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Nuclear magnetic resonance (NMR) of atomic (129/131)Xe is used as a versatile probe of the structure and dynamics of various host materials, due to the sensitivity of the Xe NMR parameters to intermolecular interactions. The principles governing this sensitivity can be investigated using the prototypic system of interacting Xe atoms. In the pairwise additive approximation (PAA), the binary NMR chemical shift, nuclear quadrupole coupling (NQC), and spin-rotation (SR) curves for the xenon dimer are utilized for fast and efficient evaluation of the corresponding NMR tensors in small xenon clusters Xe(n) (n = 2-12). If accurate, the preparametrized PAA enables the analysis of the NMR properties of xenon clusters, condensed xenon phases, and xenon gas without having to resort to electronic structure calculations of instantaneous configurations for n > 2. The binary parameters for Xe(2) at different internuclear distances were obtained at the nonrelativistic Hartree-Fock level of theory. Quantum-chemical (QC) calculations at the corresponding level were used to obtain the NMR parameters of the Xe(n) (n = 2-12) clusters at the equilibrium geometries. Comparison of PAA and QC data indicates that the direct use of the binary property curves of Xe(2) can be expected to be well-suited for the analysis of Xe NMR in the gaseous phase dominated by binary collisions. For use in condensed phases where many-body effects should be considered, effective binary property functions were fitted using the principal components of QC tensors from Xe(n) clusters. Particularly, the chemical shift in Xe(n) is strikingly well-described by the effective PAA. The coordination number Z of the Xe site is found to be the most important factor determining the chemical shift, with the largest shifts being found for high-symmetry sites with the largest Z. This is rationalized in terms of the density of virtual electronic states available for response to magnetic perturbations.

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Probing the pore space in mesoporous materials by laser enhanced hyperpolarised 129Xe NMR

Cited by 8 publications

References 28 publications

Evidence of Specific Interactions between Laser-Polarized Xenon and Arenesulfonic Acid Groups in Functionalized SBA-15 Materials

Evidence of Specific Interactions between Laser-Polarized Xenon and Arenesulfonic Acid Groups in Functionalized SBA-15 Materials

Infrared investigations of arenesulfonic modified mesoporous materials by the use of complementary probes

Pairwise additivity in the nuclear magnetic resonance interactions of atomic xenon

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