Electron Spin Resonance and Electron Spin Echo Modulation Studies of Cupric Ion Ion-Exchanged into Siliceous MCM-41

Poeppl, Andreas; Newhouse, Mike; Kevan, Larry

doi:10.1021/j100024a051

Cited by 44 publications

(35 citation statements)

References 6 publications

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“…One such species (A in Table 1 ) shows spin-Hamiltonian parameters typical for [Cu(H 2 O) 6 ] 2+ complexes (Fig. 1e ) 48 , 49 . The other species (B in Table 1 ) has spin-Hamiltonian parameters consistent with a tetragonally elongated 6-coordination, i.e.…”

Section: Resultsmentioning

confidence: 99%

17O-EPR determination of the structure and dynamics of copper single-metal sites in zeolites

Bruzzese

Salvadori

Jäger³

et al. 2021

Nat Commun

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The bonding of copper ions to lattice oxygens dictates the activity and selectivity of copper exchanged zeolites. By 17O isotopic labelling of the zeolite framework, in conjunction with advanced EPR methodologies and DFT modelling, we determine the local structure of single site CuII species, we quantify the covalency of the metal-framework bond and we assess how this scenario is modified by the presence of solvating H216O or H217O molecules. This enables to follow the migration of CuII species as a function of hydration conditions, providing evidence for a reversible transfer pathway within the zeolite cage as a function of the water pressure. The results presented in this paper establish 17O EPR as a versatile tool for characterizing metal-oxide interactions in open-shell systems.

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Section: Resultsmentioning

confidence: 99%

17O-EPR determination of the structure and dynamics of copper single-metal sites in zeolites

Bruzzese

Salvadori

Jäger³

et al. 2021

Nat Commun

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“…The extracted values are, however, clearly indicative of an equatorially bound OH À group. 39,41 The negative sign for the Fermi contact term can be qualitatively understood on the basis of a spin polarization mechanism, considering that the unpaired electron dwells in a molecular orbital which is mainly 3d x 2 Ày 2 in character (with small admixtures of oxygen non-bonding orbitals). A similar situation holds in the case of the Cu(H 2 O) 6 2+ complex.…”

Section: Hyscore Resultsmentioning

confidence: 99%

Spectroscopic CW-EPR and HYSCORE investigations of Cu2+ and O2− species in copper doped nanoporous calcium aluminate (12CaO·7Al2O3)

Maurelli

Ruszak

Witkowski

et al. 2010

Phys. Chem. Chem. Phys.

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Continuous wave (CW) and pulse electron paramagnetic resonance in a variant of hyperfine sublevel correlation spectroscopy (HYSCORE) were used for obtaining structural information concerning speciation and local environment of alien Cu(2+) and native O(2)(-) ions encaged in copper doped nanoporous 12CaO.7Al(2)O(3) (mayenite). The samples were prepared by a solid-state reaction and characterized by means of XRD, SEM, and Raman techniques. X-Band CW-EPR spectra showed that three different Cu(2+) species together with paramagnetic extraframework O(2)(-) anions were present in the mayenite sample, whereas extraframework OH(-) anions were revealed by Raman spectroscopy. (27)Al HYSCORE provided evidence for the interaction of Cu(2+) ions with the mayenite framework. Superhyperfine interaction of the Cu(2+) ions with proximal (d(Cu-OH) = 2.4 A) and distal (d(Cu-OH) = 5.0 A) OH(-) anions, located in the same and the nearby cage, respectively, was resolved by means of (1)H HYSCORE spectra. A different situation held for the encaged O(2)(-) radicals found to be sitting on the Ca(2+) ions. They exhibited only a weak superhyperfine interaction of 1 MHz with the (27)Al(3+) framework ions.

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“…10,11 However, application of basic scientific principles to the key technological issues involved has been difficult, and more progress has been achieved through manipulation of processing parameters than through understanding of the chemical and physical mechanisms that affect property-function relations of guest materials. Cupric ions have been introduced into mesoporous silicas by liquid and solid ion exchange to adsorb ethylene and carotenoids, while the geometry of adsorbed water and ammonia molecules with respect to the copper ion has been investigated; 12,13 however much less is known about the impact of different preparation procedures on the final dispersion of copper species in SBA-15 and their function for adsorbing nitrosamines in gaseous and liquid phases. SBA-15 materials generally possess rough pore walls with micro-and narrow mesopores that coexist with the regular hexagonal framework of main channels; 14 it is necessary to know which porous structure the copper preferably fills.…”

Section: Introductionmentioning

confidence: 99%

Solvent-free surface functionalized SBA-15 as a versatile trap of nitrosamines

et al. 2006

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Dispersion of copper oxide via a solvent-free method enables mesoporous silica SBA-15 to become a versatile trap of nitrosamines, exhibiting a high capability to capture volatile nitrosamines and tobacco special nitrosamines (TSNA). 3%CuO/SBA-15 can remove 85% of N-nitrosopyrrolidine (NPYR) in gaseous flow, one fifth more than that by the analogous via one-pot method, while 5%CuO/SBA-15 traps all N-nitrosonornicotine (NNN) in solution with a concentration of 0.6 mmol l 21 , superior to NaY zeolite. The dispersion of the copper guest in SBA-15 is assessed by XRD, H 2 -TPR, NO 2 -TPD and UV-Vis methods.

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Electron Spin Resonance and Electron Spin Echo Modulation Studies of Cupric Ion Ion-Exchanged into Siliceous MCM-41

Cited by 44 publications

References 6 publications

17O-EPR determination of the structure and dynamics of copper single-metal sites in zeolites

17O-EPR determination of the structure and dynamics of copper single-metal sites in zeolites

Spectroscopic CW-EPR and HYSCORE investigations of Cu2+ and O2− species in copper doped nanoporous calcium aluminate (12CaO·7Al2O3)

Solvent-free surface functionalized SBA-15 as a versatile trap of nitrosamines

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