Hydrolysis and polycondensation of Si(OEt)4: A mass spectrometry approach to the definition of reaction intermediates in the presence of acid or basic catalysts. Part 1

Campostrini, R.; Carturan, G.; Pelli, Beatrice; Traldi, Pietro

doi:10.1016/0022-3093(89)90576-0

Cited by 26 publications

(15 citation statements)

References 19 publications

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“…One method which has been used to study the components present during hydrolysis and polycondensation reactions is mass spectrometry. In previous studies, mass spectrometry has been used to study the polycondensation reaction of TEOS [Si(OC 2 H 5 ) 4 ], either in the gas phase via chemical ionization (CI) experiments [12] or in the condensed phase by continuous flow fast atom bombardment (FAB) [13] and electrospray ionization mass spectrometry (ESI-MS) [14]. In the latter investigation it was shown that the polycondensation reaction is initiated by a protonated molecule.…”

Section: Introductionmentioning

confidence: 99%

Sol–gel reactions of titanium alkoxides and water: influence of pH and alkoxy group on cluster formation and properties of the resulting products

Simonsen

Søgaard

2009

J Sol-Gel Sci Technol

102

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In this work the effect of pH and the titanium precursor on the cluster and particle formation during titanium alkoxide based sol-gel processes was investigated using electrospray ionization mass spectrometry (ESI-MS) and dynamic light scattering (DLS). The influence of pH and the titanium precursor on the particle size, morphology, crystallinity and chemical composition of the resulting particles were investigated using differentiel scanning calometry (DSC), X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FT-IR), BET-adsorption isotherms and high resolution transmission electron microscopy (HR-TEM). ESI-MS investigation of the titanium clusters present during the nucleation and growth period showed that the number of titanium atoms in the clusters varied dependent on the alkoxide used. Moreover, it was found that the titanium clusters formed using titanium tetraethoxide (TTE) were smaller than the clusters formed by titanium tetraisopropoxide (TTIP) and titanium tetrabutoxide (TTB) under similar conditions. pH was not found to influence the nature of the titanium clusters present in the sol-gel solution. HR-TEM investigation of the TiO 2 particles prepared at pH 7 and 10 showed that the primary particle size of the particles was around 3 nm. However, it was found that these primary particles aggregated to form larger secondary particles in the size order of 300-500 nm range. At pH 3 the particles grew significantly during the drying process due to destabilization of the colloidal solution leading to the formation of a gel. The highest specific surface area was found for particles synthesized under neutral or alkaline conditions based on TTIP. XRD analysis of the TiO 2 particles showed that the particles synthesized at 25°C were amorphous. First after heating the samples to above 300°C the formation of anatase were observed.

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Section: Introductionmentioning

confidence: 99%

Sol–gel reactions of titanium alkoxides and water: influence of pH and alkoxy group on cluster formation and properties of the resulting products

Simonsen

Søgaard

2009

J Sol-Gel Sci Technol

102

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“…The Biosil method provides a novel, versatile technology for entrapment of animal cells that can be applied easily to different geometries (11,12,22,23). Silicon alkoxide precursors available from a gas phase form a homogeneous porous layer by reacting with hydroxyl groups and surface water.…”

Section: Discussionmentioning

confidence: 99%

SiO₂ Entrapment of Animal Cells: Liver‐Specific Metabolic Activities in Silica‐Overlaid Hepatocytes

et al. 2002

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Rat hepatocytes in a collagen-gel sandwich configuration were exposed to silicon alkoxides in a gas phase, yielding a 0.05 to 0.15 microm porous silica layer on the gel surface. Cell viability was unaffected by the procedure. After 24 h, bilirubin conjugation, ammonia removal, urea synthesis, and diazepam metabolism were unaffected by the procedure. However, both the ammonia removal rate and diazepam metabolism were increased after 48 hr, whereas urea synthesis was unaffected. These data indicate that silica overlay allows efficient metabolic activity of collagen-gel entrapped hepatocytes. The fact that the KM of bilirubin conjugation was unaffected by the presence of the silica membrane suggests that the transport of albumin-bound substrates is not decreased. The enhancement in some metabolic activities found 48 h after the entrapment procedure may be the result of favorable changes in the hepatocyte microenvironment. These characteristics might be useful for the development of organotypical bioartificial liver devices.

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“…An interesting gas‐phase study was conducted by EI‐MS on tetraethoxyorthosilicate (TEOS, [Si(OCH 2 CH 3 ) 4 ]), one of the most important sol‐gel precursors, to evaluate its reactivity toward electrophiles and nucleophiles and try to detect possible intermediates in the polymerization process (Campostrini et al, ). In the first part of this study, the time‐dependent variation in concentration of the decomposition products is evaluated (Fig.…”

Section: Mass Spectrometry In the Study Of The Sol‐gel Processesmentioning

confidence: 99%

“…Time‐dependent variation of the concentrations of the decomposition products detected in the EI spectra of TEOS. Adapted from Campostrini et al () with permission.…”

Section: Mass Spectrometry In the Study Of The Sol‐gel Processesmentioning

confidence: 99%

Mass spectrometry in the characterization of reactive metal alkoxides

Peruzzo

Chiurato

Favaro

et al. 2016

Mass Spectrometry Reviews

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Metal alkoxides are metal-organic compounds characterized by the presence of MOC bonds (M = metal). Their chemistry seems to be, in principle, relatively simple but the number of possible reactant species arising as a consequence of their behavior is very remarkable. The physico-chemical properties of metal alkoxides are determined by many different parameters, the most important ones being the electronegativity of the metal, the ramification of the ligand, and the acidity of the corresponding alcohol. Their reactivity makes them suitable and versatile candidates for many applications, including homogeneous catalysis, synthesis of new ceramic materials through the sol-gel process and, recently, also for Cultural Heritage. Metal alkoxides are characterized by a strong tendency to give clusters and/or oligomers through oxo-bridges. Mass spectrometry has been successfully employed for the characterization of metal alkoxides in the gas-phase. Electron ionization (EI) allowed the assessment of the molecular weight and of the most relevant decomposition pathways giving information on the relative bond strength of differently substituted molecules. On the other hand, information on the reactivity in solution of these molecules have been obtained by electrospray ionization (ESI)-matrix assisted laser desorption ionization (MALDI) experiments performed on their reaction products. These data were relevant to investigate the sol-gel process. In this review, these aspects are described and the results obtained are critically evaluated. © 2016 Wiley Periodicals, Inc. Mass Spec Rev.

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Hydrolysis and polycondensation of Si(OEt)4: A mass spectrometry approach to the definition of reaction intermediates in the presence of acid or basic catalysts. Part 1

Cited by 26 publications

References 19 publications

Sol–gel reactions of titanium alkoxides and water: influence of pH and alkoxy group on cluster formation and properties of the resulting products

Sol–gel reactions of titanium alkoxides and water: influence of pH and alkoxy group on cluster formation and properties of the resulting products

SiO₂ Entrapment of Animal Cells: Liver‐Specific Metabolic Activities in Silica‐Overlaid Hepatocytes

Mass spectrometry in the characterization of reactive metal alkoxides

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Hydrolysis and polycondensation of Si(OEt)4: A mass spectrometry approach to the definition of reaction intermediates in the presence of acid or basic catalysts. Part 1

Cited by 26 publications

References 19 publications

Sol–gel reactions of titanium alkoxides and water: influence of pH and alkoxy group on cluster formation and properties of the resulting products

Sol–gel reactions of titanium alkoxides and water: influence of pH and alkoxy group on cluster formation and properties of the resulting products

SiO2 Entrapment of Animal Cells: Liver‐Specific Metabolic Activities in Silica‐Overlaid Hepatocytes

Mass spectrometry in the characterization of reactive metal alkoxides

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SiO₂ Entrapment of Animal Cells: Liver‐Specific Metabolic Activities in Silica‐Overlaid Hepatocytes