Host- guest interactions in zeolite cavities

Zecchina, Adriano; Buzzoni, R.; Bordiga, Silvia; Geobaldo, Francesco; Scarano, Domenica; Ricchiardi, Gabriele; Spoto, G.

doi:10.1016/s0167-2991(06)81892-6

Cited by 32 publications

(32 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This perturbation effect is not only documented for a number of hydrogen-bonded compounds in the crystalline state 172 and for homogeneous systems in solutions 173 but also for heterogeneous systems like those encountered in zeolite channels 137,145,174 and on the surface of oxides. 175,176 In particular, one of the key questions associated with the activity of Brønsted groups present in zeolite channels is related to the estimation of their acid strength and its comparison with that of the most common mineral acids and superacids.…”

Section: Brønsted Acidity In Zeolites Investigated By Probe Moleculesmentioning

confidence: 90%

“…It can detect Lewis and Brønsted sites, 4,136,137,146,177,198,202,317,[668][669][670][671][672][673] and is able to locate sites in small pores, even side pockets of mordenite, 212,674 as shown in Fig. It can detect Lewis and Brønsted sites, 4,136,137,146,177,198,202,317,[668][669][670][671][672][673] and is able to locate sites in small pores, even side pockets of mordenite, 212,674 as shown in Fig.…”

Section: Acetonitrile and Substituted Acetonitrile (Deuterated)mentioning

confidence: 98%

“…The observations illustrated in Fig. The reasons for this choice are twofold: (i) the acetonitrile probe (CH 3 CN and CD 3 CN) has been studied extensively with a great variety of zeolites 137,146,151,177,186,[197][198][199][200][201][202] and (ii) the acetonitrilezeolite complex is characterized by a complex spectroscopy generated by Fermi resonance effects. In accordance with the immense literature on the IR spectroscopy of hydrogen-bonded systems, the shift to a lower frequency and the increase in bandwidth are due to the decrease in the force constant induced by the polarization of the O-H bond and by coupling of the n(OH) mode with the n(OÁ Á ÁB) modes of the adducts, which consequently can be better expressed as n(OHÁ Á ÁB) AE n(OÁ Á ÁB).…”

Section: Brønsted Acidity In Zeolites Investigated By Probe Moleculesmentioning

confidence: 99%

“…Therefore, we move to acetonitrile (PA = 188.6 kcal mol À1 ). The reasons for this choice are twofold: (i) the acetonitrile probe (CH 3 CN and CD 3 CN) has been studied extensively with a great variety of zeolites 137,146,151,177,186,[197][198][199][200][201][202] and (ii) the acetonitrilezeolite complex is characterized by a complex spectroscopy generated by Fermi resonance effects. 145,186 Because these effects are dominant in the spectra of the adducts of structural Brønsted sites with bases of medium-strong PA, their detailed illustration for acetonitrile complexes can be useful for the comprehension of a great variety of experiments that involve different and stronger bases.…”

Section: Zh + B -Zhá á áBmentioning

confidence: 99%

See 3 more Smart Citations

Probing zeolites by vibrational spectroscopies

et al. 2015

View full text Add to dashboard Cite

This review addresses the most relevant aspects of vibrational spectroscopies (IR, Raman and INS) applied to zeolites and zeotype materials. Surface Brønsted and Lewis acidity and surface basicity are treated in detail. The role of probe molecules and the relevance of tuning both the proton affinity and the steric hindrance of the probe to fully understand and map the complex site population present inside microporous materials are critically discussed. A detailed description of the methods needed to precisely determine the IR absorption coefficients is given, making IR a quantitative technique. The thermodynamic parameters of the adsorption process that can be extracted from a variable-temperature IR study are described. Finally, cutting-edge space- and time-resolved experiments are reviewed. All aspects are discussed by reporting relevant examples. When available, the theoretical literature related to the reviewed experimental results is reported to support the interpretation of the vibrational spectra on an atomic level.

show abstract

Section: Brønsted Acidity In Zeolites Investigated By Probe Moleculesmentioning

confidence: 90%

Section: Acetonitrile and Substituted Acetonitrile (Deuterated)mentioning

confidence: 98%

Section: Brønsted Acidity In Zeolites Investigated By Probe Moleculesmentioning

confidence: 99%

Section: Zh + B -Zhá á áBmentioning

confidence: 99%

See 2 more Smart Citations

Probing zeolites by vibrational spectroscopies

et al. 2015

View full text Add to dashboard Cite

show abstract

“…[18][19][20] Nevertheless, some of the parameters that control the reaction and the subsequent electron transfer remain unclear and require complementary investigations. Previous experiments showed that the spontaneous ionization of low-ionization-potential molecules could occur only within a highly polarizing internal space.…”

Section: Introductionmentioning

confidence: 99%

Spontaneous Ionization of N‐Alkylphenothiazine Molecules Adsorbed in Channel‐Type Zeolites: Effects of Alkyl Chain Length and Confinement on Electron Transfer

Carré¹,

Luchez²,

Moissette³

et al. 2011

ChemPhysChem

View full text Add to dashboard Cite

The mere mixing of N-alkylphenothiazines with three channel-type acid zeolites with various structures (ferrierite, H-MFI, and mordenite) induces the spontaneous ionization of the heterocyclic molecule in high yield upon adsorption. The diffuse reflectance UV-visible absorption and Raman scattering spectra show that the accessibility of the highly polarizing acid sites is not indispensable to induce the spontaneous ionization process. Due to their particularly low ionization potential values (6.7 eV), the adsorption of the molecules on the external surface or in the inner volume is the key parameter to generate the radical cation. However, the ionization yield and charge stabilization are intimately correlated to the possibility of the zeolites accommodating molecules inside their channels. Moreover, the higher electrostatic field gradient induced by high confinement is required to favor the second ionization and dication formation. The alkyl chain length plays a decisive role by either slowing down the diffusion process or blocking the molecule at the pore entry. Therefore, the efficiency of the ionization process that depends on the number of adsorbed molecules decreases significantly from phenothiazine to the N-alkylphenothiazines. The spectral data demonstrate that deformation of the alkyl group is necessary to allow the diffusion of the molecules into the channels.

show abstract

Solid Acid Catalysis, Theory and Reaction Mechanisms

2017

Modern Heterogeneous Catalysis

View full text Add to dashboard Cite

Host- guest interactions in zeolite cavities

Cited by 32 publications

References 13 publications

Probing zeolites by vibrational spectroscopies

Probing zeolites by vibrational spectroscopies

Spontaneous Ionization of N‐Alkylphenothiazine Molecules Adsorbed in Channel‐Type Zeolites: Effects of Alkyl Chain Length and Confinement on Electron Transfer

Solid Acid Catalysis, Theory and Reaction Mechanisms

Contact Info

Product

Resources

About