Kinetics of interaction of 3-aminopropyltriethoxysilane on a silica gel surface using elemental analysis and diffuse reflectance infrared Fourier transform spectra

Shimizu, Ichiro; Yoshino, Atsuo; Okabayashi, Hirofumi; Nishio, Etsuo; O’Connor, Charmian J.

doi:10.1039/a608121e

Cited by 45 publications

(53 citation statements)

References 21 publications

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“…As already mentioned in the Introduction section, the reaction between the methoxy groups from the APTMS and the free OH from the activated silica gel is irreversible [26]. Thus, almost all APTMS will be chemisorbed from the toluene solution on the silica gel surface, until the maximum APS chemisorption occurs.…”

Section: Determining the Maximum Amount Of Attached Apsmentioning

confidence: 84%

“…The increase in the band intensities of (CH 2 ), (NH 2 ), and (NH 2 ) from the attached APS groups, suggested that the maximum adsorption on the silica gel occurred for w/w APTMS at around 19 %. The nucleophilic substitution here used for grafting is an irreversible process [26], thus almost the entire amount of initially added APTMS was chemisorbed on the silica gel, until saturation occurred. This was the condition needed to find the unreacted amount of APTMS in the solution of toluene and subtract it from the initial amount, in order to calculate the chemisorbed one.…”

Section: Discussionmentioning

confidence: 99%

“…However, if the process of adsorption is an actual chemisorption and the reaction is irreversible, then the equilibrium concentration in the solution will be negligible, without the possibility of being measured (particularly not using IR). The reaction between the ethoxy (methoxy) groups and the OH groups from the silica gel (used in this work) is an example of such irreversible reaction [26].…”

Section: Introductionmentioning

confidence: 99%

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Indirect quantitative IR assessment of maximal monomolecular deposition of 3-aminopropyltrimethoxysilane on silica gel surface

Bukleski

Ivanovski

2014

Maced. J. Chem. Chem. Eng.

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Quantification of the amount of maximum loaded 3-aminopropylsilyl (APS) on a thermally pretreated silica gel (600 ºC) was performed using IR spectroscopy. Finding the maximum load through a construction of a Langmuir isotherm was not possible due to the irreversibility of the chemisorption reaction. The method used in this work was based on the analysis of the toluene solution on the quantity of the non-reacted 3-aminopropyltrimethoxysilane (APTMS) after the saturation of the silica gel surface with APS. The process of chemisorption was monitored via the increasing band intensity of (CH 2 ), (NH 2 ), and (NH 2 ) modes of the adsorbent and decreasing (OH) band intensity characteristic for the free isolated OH groups of silica gel using DRIFT spectroscopy. The results on maximum adsorption are in line with those previously obtained, using carbon elemental analysis and a direct DRIFT method.Keywords: 3-aminopropyltrimethoxysilane (APTMS); chemisorption; DRIFT spectra; modified silica gel ИНДИРЕКТНО КВАНТИТАТИВНО ОПРЕДЕЛУВАЊЕ МАКСИМАЛНА МОНОМОЛЕКУЛАРНА ДЕПОЗИЦИЈА НА 3-АМИНОПРОПИЛТРИМЕТОКСИСИЛАН НА ПОВРШИНАТА ОД СИЛИКАГЕЛ СО ИНФРАЦРВЕНА СПЕКТРОСКОПИЈАКвантификацијата на максимално нафатеното количество 3-аминопропилсилил (APS) на температурно активиран силикагел (600 ºC) беше спроведена со помош на инфрацрвена спектроскопија. Определувањето на максимално нафатеното количество преку конструкција на Лангмјурова изотерма не е можно како резултат на иреверзибилноста на хемиската реакција. Користениот метод во оваа работа беше базиран на анализа на растворот од толуен во однос на содржината на неизреагиран 3-аминопропилтриметоксисилан (APTMS) по заситувањето на површината на силикагелот со групи на APS. Процесот на хемисорпција беше следен преку зголемувањето на интензитетот на лентите од модовите на(CH 2 ), (NH 2 ) и (NH 2 ) од атсорби-раните молекули и намалувањето на интензитетот на модот(OH) од слободните, т.е. изолирани OH-групи од силикагелот, со помош на DRIFT спектроскопијата. Добиените резултати за максималната атсорпција се во согласност со претходно добиените од елементарна анализа и со оние добиени со примена на директниот DRIFT-метод.Клучни зборови: 3-аминопропилтриметоксисилан (APTMS); хемисорпција; DRIFT спектри; модифициран силика гел M. Bukleski, V. Ivanovski Maced.

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Section: Determining the Maximum Amount Of Attached Apsmentioning

confidence: 84%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Indirect quantitative IR assessment of maximal monomolecular deposition of 3-aminopropyltrimethoxysilane on silica gel surface

Bukleski

Ivanovski

2014

Maced. J. Chem. Chem. Eng.

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“…Solid-state 13 C and 29 Si NMR experiments were performed on a Bruker DRX300 spectrometer (7.05 T), operating at Larmor frequencies of 75.4 and 59.3 MHz respectively and equipped with a 4 mm Bruker CPMAS probe and ZrO 2 rotors, spinning at 6 kHz ( 13 C) and 5 kHz ( 29 Si). For 13 C NMR spectra, the 1 H-13 C cross polarisation magic angle spinning (CPMAS) pulse sequence was employed, with optimised contact time of 2 ms and a repetition time (D1) of 4 s. 29 Si MAS NMR spectra were acquired by using both 1 H-29 Si cross polarisation (CPMAS) with contact time of 4 ms 27 and direct polarisation with high power 1 H dipolar decoupling (HPDD) pulse sequences. In this case experiments were performed by using repetition times from 10 to 300 s based on literature data for similar samples.…”

Section: Methodsmentioning

confidence: 99%

“…We conclude, therefore, that the incorporation of 1,4-naphthoquinones onto modified silica NPs is easily carried out via the same route used for the synthesis of amino-substituted 1,4-naphthoquinones. 26,36 The fact that some amine groups remained unreacted might be associated to the oligomerization or polymerization of silane molecules bound to the silica surface (see above NMR discussion) 29 making it difficult for the amine to react with the naphthoquinone. …”

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confidence: 99%

Modified silica nanoparticles with an Aminonaphthoquinone

Silveira¹,

Ronconi²,

Vargas³

et al. 2011

J. Braz. Chem. Soc.

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Nanopartículas de sílica (NPs) modificadas covalentemente com uma aminonaftoquinona foram sintetizadas e caracterizadas. A aminopropilsilicagelnaftoquinona (APSGNQ) foi obtida por substituição nucleofílica do grupo metóxi da 2-metóxi-1,4-naftoquinona por NPs modificadas com o grupo aminopropil (APSG). Os espectros de ressonância magnética nuclear de 13 C e 29 Si no estado sólido confirmaram que a naftoquinona encontra-se ligada covalentemente à aminopropilsilicagel. Como o composto APSGNQ é solúvel em solventes orgânicos comuns, foi possível quantificar o ancoramento da naftoquinona na superfície das NPs modificadas por espectroscopia no ultravioletavisível (0,56 mmol de naftoquinona ancorada por grama de APSGNQ), por comparação com o espectro do composto análogo 2-aminobutil-1,4-naftoquinona (ABNQ). Os dados das análises elementares indicaram que aproximadamente 8% da propilamina presente na superfície do composto APSGNQ não reagiu com a metóxinaftoquinona. Essas NPs de sílica multifuncionais têm potencial para aplicações médicas.The synthesis and characterization of silica nanoparticles (NPs) covalently modified with an aminonaphthoquinone are reported. The aminopropylsilicagelnaphthoquinone (APSGNQ) was obtained by nucleophilic substitution of 2-methoxy-1,4-naphthoquinone with aminopropylsilicalgel (APSG) NPs. Solid state 13 C and 29 Si nuclear magnetic resonance spectra confirmed that the naphthoquinone is covalently bonded to APSG. Due to the solubility of APSGNQ in common organic solvents, solution ultraviolet-visible spectroscopy was used to determine the amount of naphthoquinone on the NPs surface (0.56 mmol of incorporated naphthoquinone per gram of APSGNQ) by comparison with the spectrum of 2-aminobutyl-1,4-naphthoquinone (ABNQ). Elemental analysis indicated that about 8% of the surface propylamine remained unreacted in APSGNQ. These multifunctional silica NPs have potential in medical applications. ). 23 The presence of amino groups has been shown to potentiate some of these biological activities. Keywords 20,24Herein we describe the successful anchoring of an aminonaphthoquinone on silica NPs. To the best of our knowledge, NPs containing covalently-bound naphtoquinones have not yet been reported in the literature. Experimental Materials and methodsThe silica nanoparticles (NPs) (Aldrich, 15 nm, 637238) were pretreated under high vacuum at 180 °C for 10 h to remove adsorbed water. 3-Aminopropyltriethoxysilane and butylamine, both from Aldrich, were used without prior treatment. Toluene (Vetec) was previously dried with sodium/benzophenone under argon; methanol and ethanol were used as received. ). Thermogravimetric analyses were conducted with a Netzsch STA 409 PC TG/DTA equipment. Approximately 10 mg of sample were weighed in an alumina crucible and heated at 35-1100 °C, at the heating rate of 5 °C min -1 , under nitrogen flow (30 cm 3 min -1 ). Elemental analyses were carried out at the Central Analítica of the Instituto de Química, Universidade de São Paulo, Brazil. Solid-state 13 C and 29 Si NMR...

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Silanol‐Assisted Aldol Condensation on Aminated Silica: Understanding the Arrangement of Functional Groups

et al. 2013

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Free silanol groups are known to promote the activity of aminated silica. In this work the effect of the silanol‐to‐amine ratio on the aldol condensation of 4‐nitrobenzaldehyde and acetone is investigated in a range from 0 to 2.4. Irrespective of the amine density, identical, moderate turnover frequencies are obtained if the silica exclusively has amines on its surface. The turnover frequency increases with increasing silanol‐to‐amine ratio until an upper limit is reached at a silanol‐to‐amine ratio of 1.7. At this upper limit the turnover frequency is a factor 5 higher than the turnover frequencies obtained with the monofunctional amine‐based catalysts. This increase is ascribed to hydrogen‐bridge interactions between the silanols and the carbonyl moiety of the reactants that provoke a more easy interaction between the carbonyl moiety and the amine as required for the aldol condensation. The observation that higher values than one for the silanol‐to‐amine ratio are required is rationalized by computer simulations. It was found that amine groups were grafted on the silica surface in a clustered manner, originating from positive deviations from ideality in the synthesis mixture, that is, from clustering of the amine precursor in the liquid phase.

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Kinetics of interaction of 3-aminopropyltriethoxysilane on a silica gel surface using elemental analysis and diffuse reflectance infrared Fourier transform spectra

Cited by 45 publications

References 21 publications

Indirect quantitative IR assessment of maximal monomolecular deposition of 3-aminopropyltrimethoxysilane on silica gel surface

Indirect quantitative IR assessment of maximal monomolecular deposition of 3-aminopropyltrimethoxysilane on silica gel surface

Modified silica nanoparticles with an Aminonaphthoquinone

Silanol‐Assisted Aldol Condensation on Aminated Silica: Understanding the Arrangement of Functional Groups

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