Silicon-29 NMR study of silica

Extended Investigations on Luminescent Cs2[Mo6Br14]@SiO2 Nanoparticles: Physico-Structural Characterizations and Toxicity Studies

“…The spectra of both samples (Figure 9) show three signals at chemical shifts of δ = −90, −100, and −110 ppm respectively assigned to Q 2 geminal silanols, Q 3 free silanols, and Q 4 siloxane bridges (see Figure 9). 45 The integrated areas calculated after deconvolution of the three signals indicated a decrease of 20% of the proportion in Q 4 silicon in Cs 2 [Mo 6 Br 14 ]@SiO 2 nanoparticles compared to SiO 2 nanoparticles. However, this decreased can also be interpreted as an increase of the silanols in the silica matrix.…”

Amorphous Silica as a Versatile Supermolecular Ligand for NiII Amine Complexes: Toward Interfacial Molecular Recognition

“…Si NMR spectrum of Aerosil 380 is presented in Figure 4. Mathematical decomposition of this spectrum allows determination of silanol density by the method of Lÿonardelli et al [16] This method is based on the measurement of the integrated surface of each peak, which is proportional to the percentage of the corresponding silicon species. As reported in Table 3, Aerosil 380 has a total silanol density of 5.1 nm À2 , of which 4.4 nm À2 are terminal and 0.7 nm À2 are geminal.…”

“…The 29 Si chemical shifts d Si were referenced to TMS. Mathematical decomposition of 29 Si NMR spectra was performed by using the ™Winfit∫ package to quantify the density of silanol groups by the method of Lÿonardelli et al [16] The Gaussian/Lorenzian ratio used for peak modeling was 0.55.…”

Étude par des expériences HETCOR 1H–29Si des interfaces tensioactif/silice dans des matériaux mésostructurés à porosité ordonnée

“…2a [23,28,29] des trois espèces de Si présents dans une matrice de silice : Q 4 = SiO 2 , Q 3 = SiO 1,5 O t , Q 2 = SiO(O t ) 2 (O t : oxygène non pontant); les pourcentages de chaque espèce montrent qu'en milieu basique (MCM-41), le réseau est plus condensé (SBA-3) qu'en milieu acide, résultat bien connu en synthèse sol-gel [30]. Les spectres RMN-MAS 1 H et 29 Si à une dimension permettent donc d'identifier, sans problème de résolution, les sites présents dans le système hybride matrice silicique/tensioactif.…”