Solid-state high-resolution silicon-29 chemical shifts in silicates

Mägi, Μ.; Lippmaa, É.; Samoson, Ago; Engelhardt, G.; Grimmer, A.‐R.

doi:10.1021/j150652a015

Cited by 510 publications

(298 citation statements)

References 2 publications

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“…Figure 2 shows the solid state Si-NMR spectra of TEOS and VTES. 29 Si-RMN solid state spectrum of TEOS coating shows signals associated to Q 2 , Q 3 and Q 4 . The intensity ratios of these signals indicated a high number of terminal silanol groups, which suggests an incomplete condensation process ( Table 2).…”

Section: Structural Characterizationmentioning

confidence: 99%

“…The VTES and TEOS (pure material) films were studied by 29 Si solid RMN after a condensation treatment. The nomenclature followed for the description of the behaviour of the precursors was described extensively in other papers [27][28][29].…”

Section: Structural Characterizationmentioning

confidence: 99%

“…The nomenclature followed for the description of the behaviour of the precursors was described extensively in other papers [27][28][29]. The most useful information from these spectra is the determination of the condensation degree of each precursor used to form the film.…”

Section: Structural Characterizationmentioning

confidence: 99%

“…Films from precursor mixtures (9VTES-1TEOS, 8VTES-2TEOS, 7VTES-3TEOS) were prepared and the 7VTES-3TEOS sample was studied by 29 Si solid RMN (Fig. 3).…”

Section: Structural Characterizationmentioning

confidence: 99%

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The design and characterisation of sol–gel coatings for the controlled-release of active molecules

Hernández-Escolano

Juan-Díaz

Martínez‐Ibáñez

et al. 2012

J Sol-Gel Sci Technol

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The controlled release of active agents from a matrix has become increasingly important for oral, trans-dermal or implantable therapeutic systems, due to the advantages of safety, efficacy and patient convenience. Controlled-release hybrid (organicinorganic) sol-gel coating synthesis has been performed to create a sol with an active molecule included (procaine). Synthesis proce-dures included acid-catalysed hydrolysis, sol preparation, the addition of a procaine solution to the sol, and the subsequent gelation and drying. The alkoxide precursors used were triethoxyvinylsilane and tetraethyl-orthosilicate (TEOS) in molar ratios of 1:0, 9:1, 8:2 and 7:3. After the determination of the optimal synthesis parameters, the material was physicochemically characterised by silicon-29 nuclear magnetic resonance ( 29 Si-NMR) and Fourier transform infrared spectroscopy, contact angle analysis and electrochemical impedance spectroscopy tests. Finally, the materials were assayed in vitro for their ability to degrade by hydrolysis and to release procaine in a controlled manner. The sustained release of procaine over a 3-day period was demonstrated. A close correlation between release and degradation rates suggests that film degradation is the main mechanism underlying the control of release. Electrochemical analysis reveals the formation of pores and water uptake during the degradation. The quantity of TEOS is one of the principal parameters used to determine the kinetics of degradation and procaine release.

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Section: Structural Characterizationmentioning

confidence: 99%

Section: Structural Characterizationmentioning

confidence: 99%

Section: Structural Characterizationmentioning

confidence: 99%

“…Films from precursor mixtures (9VTES-1TEOS, 8VTES-2TEOS, 7VTES-3TEOS) were prepared and the 7VTES-3TEOS sample was studied by 29 Si solid RMN (Fig. 3).…”

Section: Structural Characterizationmentioning

confidence: 99%

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The design and characterisation of sol–gel coatings for the controlled-release of active molecules

Hernández-Escolano

Juan-Díaz

Martínez‐Ibáñez

et al. 2012

J Sol-Gel Sci Technol

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“…27 Al and 23 Na spectra were referenced to external solution standards of 0.1 M AlCl 3 (d Al = 0.0 ppm) and 0.1 M NaCl (d Na = 0.0 ppm), respectively. 29 Si spectra were referenced with respect to tetramethyl silane using solid kaolinite as an external shift reference (d Si = À92.0 ppm; Magi et al, 1984). The NMR spectra were also subjected to least squares fitting to a linear combination of pseudo-Voight lineshapes in order to extract their peak positions and integrated intensities.…”

Section: Solid-state Nmr Spectroscopymentioning

confidence: 99%

The formation of metastable aluminosilicates in the Al–Si–H2O system: Results from solution chemistry and solid-state NMR spectroscopy

Mason

Maxwell

Carroll

2011

Geochimica et Cosmochimica Acta

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We present the results of a series of experiments designed to probe the interactions between Al and the amorphous silica surface as a function of thermodynamic driving forces. The results from 27 Al single pulse magic angle spinning (SP/MAS) and 27 Al{ 1 H} rotational echo double resonance (REDOR) allow us to identify the reaction products and constrain their structure. In all cases, despite low Al and Si concentrations we observe the formation of metastable aluminosilicates. Results from low temperature experiments indicate that despite thermodynamic driving forces for the formation of gibbsite we observe the precipitation of separate octahedrally coordinated Al (Al [6] ) and tetrahedrally coordinated Al (Al [4] ) silicate phases. At higher temperatures the Al [4] silicate phase dominates the speciation. Structural models derived from the NMR data are also proposed, and the results are discussed as they relate to previous work on Al/Si cycling. Published by Elsevier Ltd.

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Characterization of the surface organization of nanostructured hybrid organic-inorganic materials by time-of-flight secondary ion mass spectrometry

Cerveau

Corriu

Dabosi

et al. 1999

Rapid Commun. Mass Spectrom.

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Time-of-flight secondary ion mass spectrometry (TOF-SIMS) has been used to analyse the surface composition of organic-inorganic hybrid solids obtained by a sol-gel process. Gels of type O(1.5)Si-R-SiO(1. 5), obtained from bis-silylated precursors (R'O)(3)-R-Si(OR')(3) (R' = Me, Et and R = (-CH(2))(n)-, n = 1, 2, 6, 10, 12;--CH=CH-; (-CH(2))(3)NH(CH(2))(3)-; 1, 1'-ferrocenyl; (CH(2))(n)-Ph-(CH(2))(n)- with Ph = 1,4-phenylene and n = 0, 1, 2; Ph = 1,3,5-phenyl and n = 0) were analysed. The results were highly dependent on the nature of the organic group. When the organic group was small or 'rigid', the main peaks detected corresponded to SiOH and SiOR' residual groups. Fragment ions from the organic group were poorly detected in this case. When the organic group was larger and more 'flexible', characteristic mass fragment ions were detected at higher relative intensities, indicative of a different organization of the organic units in the solid. TOF-SIMS clearly showed the differences between the xerogels derived from mono- and bis-silylated organic precursors : the organic group is present at the surface of mono-silylated xerogels, whereas for bis-silylated ones, the organization is dependent on the length and the flexibility of the organic units. These TOF-SIMS results are in agreement with other features already reported. Copyright 1999 John Wiley & Sons, Ltd.

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Solid-state high-resolution silicon-29 chemical shifts in silicates

Cited by 510 publications

References 2 publications

The design and characterisation of sol–gel coatings for the controlled-release of active molecules

The design and characterisation of sol–gel coatings for the controlled-release of active molecules

The formation of metastable aluminosilicates in the Al–Si–H2O system: Results from solution chemistry and solid-state NMR spectroscopy

Characterization of the surface organization of nanostructured hybrid organic-inorganic materials by time-of-flight secondary ion mass spectrometry

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