Interaction of CH2OH with silver cation in Ag–A/CH3OH zeolite: A DFT study

Danilczuk, Marek; Pogocki, Dariusz; Lund, Anders

doi:10.1016/j.cplett.2008.12.060

Cited by 6 publications

(8 citation statements)

References 45 publications

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“…The spectrum observed in this work at increased temperature can be accounted for by the attachment of the initial radical (CH 3 ) 2 ĊCOOCH 3 , (R), to the vinyl group of MMA forming a secondary radical with the structure RC β H 2 Ċ α (CH 3 )COOCH 3 . EPR spectra of this type of radicals observed in the solid phase with hyperfine splittings a CH3 = 22.2 G to the methyl protons and a β1 = 14.7 G, a β2 = 7.5 G of the methylene group [50] are very similar to that in Figure 4 (b).…”

Section: Radical Reactionsmentioning

confidence: 80%

“…Figure 3 (b) shows the spectrum obtained from this system. It is composed of the ordinary 7-line spectrum due to (CH 3 ) 2 ĊCOOCH 3 and a 6-line structure with a splitting constant of 22 G. The 6-line spectrum is assigned to the radical CDH 2 Ċ(CH 3 )COOCH 3 . The five methyl protons give rise to the sextet, while the hyperfine structure of the added deuterium atom is too small to be resolved.…”

Section: Methyl Methacrylate (Mma)mentioning

confidence: 99%

“…zeolites, alumina, aluminosilicalites or higher-order oxides are attractive materials in numerous applications in catalysis. Previous research has shown that those materials play a significant role in the separation and stabilization of various reactive intermediates as atoms, radicals, radical ions, and clusters [1][2][3][4][5][6][7]. Studies of such intermediates are very important for a better understanding of the mechanisms of chemical reactions in polymerization, heterogeneous catalysis, photochemistry, and radiation chemistry and biology.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Monomer- and polymer radicals of vinyl compounds: EPR and DFT studies of geometric and electronic structures in the adsorbed state

Lund

Danilczuk

2012

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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Electron paramagnetic resonance (EPR) spectroscopy was applied to study the paramagnetic species formed from styrene, 1,1-diphenylethylene, α-methylstyrene, β-methylstyrene and methylmethacrylate adsorbed on amorphous silica gel after -irradiation at 77 K. Radicals formed by the hydrogen atom addition at the vinyl group of the monomers were observed in all samples. The hydrogen atoms were shown to originate to a large extent from the adsorbent by using silica gel with deuterated silanol groups. An EPR spectrum assigned to a propagating radical was observed at increased temperature for samples containing methylmethacrylate (MMA). The structures of the adsorption complexes, the respective hyperfine coupling constants and the adsorption energies were calculated by applying DFT quantum chemical methods. The reaction between an MMA molecule and the MMA radical and the structure of the propagating radical was modeled. The calculated hyperfine coupling constants for all radicals confirmed the assignment of the experimental spectra.3

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Section: Radical Reactionsmentioning

confidence: 80%

Section: Methyl Methacrylate (Mma)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Monomer- and polymer radicals of vinyl compounds: EPR and DFT studies of geometric and electronic structures in the adsorbed state

Lund

Danilczuk

2012

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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“…It is proposed that these results may provide a deeper understanding of the electronic and catalytic properties of zeolites containing silver atoms and clusters. 157 The formation of radicals by the reaction between CO 2 molecules and an MgO surface precovered with K atoms has been investigated using DFT calculations and EPR. The characteristic 4-line EPR signal from isolated K atoms is lost, and a new paramagnetic species is observed attributed to CO 2 À .…”

Section: Catalysts and Catalytic Mediamentioning

confidence: 99%

Electron spin resonance

Rhodes¹

2011

Annu. Rep. Prog. Chem., Sect. C: Phys. Chem.

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The technique variously known as Electron Spin Resonance (ESR) or Electron Paramagnetic Resonance (EPR) continues to find important applications mainly in the Biomedical, Materials and Environmental Sciences. Among the advances which feature information gleaned through its agency, are studies of enzymes and membranes, conductive polymers and novel materials, fuel cells, antioxidants, environmental samples, catalysts and photocatalysts, spin-trapping agents, spin-probes and spin-labels. High-field methods are particularly useful in obtaining improved resolution of overlapping signals and the interpretation of many systems had benefited from the use of Density Functional Theory (DFT) calculations.

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“…1). This approach has been proven to give reliable results for the CH 3 -Na + /A or CH 2 OH-Ag + /A systems [21,22]. In order to represent active Lewis sites the 6T and 3T clusters were assumed to contain one and the 6T 0 cluster three AlO À 4 groups.…”

Section: Computational Detailsmentioning

confidence: 99%