Enhancement of catalytic performance by creating shell layers on sulfonic acid-functionalized monodispersed mesoporous silica spheres

Suzuki, Tomiko M.; Nakamura, Tadashi; Sudo, Eiichi; Akimoto, Yusuke; Yano, Koichiro

doi:10.1016/j.jcat.2008.06.021

Cited by 30 publications

(29 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

Section: Synthesis and Characterizationmentioning

confidence: 99%

“…The 13 C CP-MAS NMR spectrum of the assynthesized SNSA precursor (Figure 6, a) contains four main resonance signals at 58.9, 49.9, 22.9, and 19.0 ppm. The low field peaks at 58.9 and 49.9 ppm correspond to the carbon atoms linked directly to S, N, and O atoms (C 3 , C 4 , C 6 , and C 7 , inset in Figure 6). [10,35] The signals located at around 20 ppm could be attributed to the carbon atoms far away from electron withdrawing groups, including C 1 , C 2 , C 5 , and C 8 (inset in Figure 6).…”

Section: Synthesis and Characterizationmentioning

confidence: 99%

“…[10,35] The signals located at around 20 ppm could be attributed to the carbon atoms far away from electron withdrawing groups, including C 1 , C 2 , C 5 , and C 8 (inset in Figure 6). [6] Figure 6 (b) shows the 13 C CP-MAS NMR spectrum of SBA-15-SNSA (15 %). All signals found in the spectrum in Figure 6 (a) can be also found in that in Figure 6 (b) with a slight chemical shift difference, which illustrates the successful incorporation of SNSA ZS into the silica structure.…”

Section: Synthesis and Characterizationmentioning

confidence: 99%

“…In addition to these low field signals, the samples show peaks at around -66 ppm, which can be assigned to T 3 groups [T 3 = RSi(OSi) 3 ], demonstrating that the organosiloxanes are condensed as a part of the silica framework. [6] XPS measurements for SBA-15-SNSA (10 %) were taken to investigate the status of ZS SNSA. The N 1s peak, as shown in Figure 9, has a rather asymmetrical shape, which indicates that more than one component is present.…”

Section: Synthesis and Characterizationmentioning

confidence: 99%

“…[3][4] Mesoporous silicas functionalized with acidic groups, such as sulfonic acid, Nafion, and carboxyl groups, show high activity and selectivity for classical acidpromoted organic reactions, such as esterification, FriedelCrafts acylation, and olefin polymerization. [5][6][7][8][9] Various Ngroup-modified mesoporous silicas have been used in some base-catalyzed reactions including the Heck reaction, Knoevenagel condensation, and Michael addition. [10][11][12] Recently, base-and acid-bifunctional mesoporous catalysts were developed and received great attention because a cooperative catalytic system constructed from general acid and base groups is desired for some carbon-carbon bondformation reactions.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Synthesis, Characterization, and Catalytic Properties of Two Zwitterionic Hybrid SBA‐15 Mesoporous Silicas

Yang

Wang

et al. 2012

Eur J Inorg Chem

View full text Add to dashboard Cite

Zwitterionic hybrid SBA-15 mesoporous silica materials containing both amine and sulfonic acid groups have been synthesized through cocondensation from as-synthesized zwitterionic siloxane precursors (ZS) with tetraethoxysilane (TEOS). Characterization by XRD, TEM, and N 2 adsorptiondesorption measurements show that the as-synthesized materials have ordered mesostructures. Analysis with UV, 29 Si/ 13 C cross-polarization magic angle spinning (CP-MAS) NMR, and X-ray photelectron spectroscopy (XPS) and elemental analysis demonstrates that the zwitterionic parts have been IntroductionOrdered mesoporous silica materials, such as the representative MCM-41 [1] and SBA-15, [2] with stable mesostructures, large surface areas, and size-tailored mesopores on the nanometer scale have been widely investigated and employed in many fields. Organically functionalized mesoporous silicas, in particular, have received considerable attention because various organic functional groups enlarge their practical applications to catalysis, separation, sensor, and drug delivery. [3][4] Mesoporous silicas functionalized with acidic groups, such as sulfonic acid, Nafion, and carboxyl groups, show high activity and selectivity for classical acidpromoted organic reactions, such as esterification, FriedelCrafts acylation, and olefin polymerization. [5][6][7][8][9] Various Ngroup-modified mesoporous silicas have been used in some base-catalyzed reactions including the Heck reaction, Knoevenagel condensation, and Michael addition. [10][11][12] Recently, base-and acid-bifunctional mesoporous catalysts were developed and received great attention because a cooperative catalytic system constructed from general acid and base groups is desired for some carbon-carbon bondformation reactions. [13][14][15] Lin et al. demonstrated that a general acid group, the ureidopropyl group, can activate substrates in cooperation with a general base group, the 3-[2- [a] [19][20] Kan et al. synthesized acid-base bifunctional mesoporous materials by controlling steric hindrance to prevent interactions between acid and base. [13] Although much effort has been made, precise control of the molar ratio and distribution of the acid and base centers to avoid their neutralization is still a big challenge. Zwitterions are neutral molecules with a positive and a negative electrical charge at different locations within the molecule. Their latent acidity (or basicity) could be obtained by combining 1:1 molar quantities of zwitterions with acids (or bases) possessing sufficiently low pK a (or pK b ) to convert the acidic (or basic) groups into the corresponding acids (or bases). Examples are known, such as SO 3 H-functionalized ionic liquids, which were prepared through the acidification of zwitterions containing alkanesulfonic groups by various strong donor acids. [21][22] Furthermore, CO 2 -philic ionic liquid materials were prepared by alkalizing zwitterions with quaternary ammonium hydroxides. [23] Therefore, it is very interesting to introduce zwitterions into mesoporous ...

show abstract

Section: Synthesis and Characterizationmentioning

confidence: 99%

Section: Synthesis and Characterizationmentioning

confidence: 99%

Section: Synthesis and Characterizationmentioning

confidence: 99%

Section: Synthesis and Characterizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Synthesis, Characterization, and Catalytic Properties of Two Zwitterionic Hybrid SBA‐15 Mesoporous Silicas

Yang

Wang

et al. 2012

Eur J Inorg Chem

View full text Add to dashboard Cite

show abstract

Chirally Functionalized Hollow Nanospheres Containing L‐Prolinamide: Synthesis and Asymmetric Catalysis

Gao

Liu

Tang

et al. 2010

Chemistry A European J

View full text Add to dashboard Cite

Chirally functionalized hollow nanospheres with different surface properties were successfully synthesized by co-condensation of (2S,1'R,2'R)-N-tert-butyloxycarbonylpyrrolidine-2-carboxylic acid [2'-(4-trimethoxysilylbenzylamide)cyclohexyl] amide with 1,2-bis(trimethoxysilyl)ethane or tetramethoxysilane using F127 (EO(106)PO(70)EO(106)) as surfactant in water. The TEM and N(2) sorption characterizations show that the particle size of the hollow nanosphere is 15-21 nm with a core diameter of 10-16 nm. These L-prolinamide-functionalized hollow nanospheres are highly efficient solid catalysts for the direct asymmetric aldol reaction between cyclohexanone and aromatic aldehydes. It was found that the addition of water in the reaction system not only enhanced the catalytic activity but also increased the enantioselectivity, which is probably due to the enhanced hydrogen bond between the amide oxygen atom and the hydroxyl group of water. Moreover, the catalytic activity increases sharply as the surface hydrophobicity of the hollow nanospheres increases. These hollow nanospheres are quite stable and can be reused with almost the same enantioselectivity and only a slight decrease in catalytic activity.

show abstract

Synthesis of a Large Functional Cage Compound Based on Four GaGa Single Bonds and Its Application as an Oligoacceptor: On the Way to Bio‐Organogallium Hybrid Molecules

Uhl

Voß

Müller

et al. 2011

Chemistry A European J

View full text Add to dashboard Cite

The digallium compound R(2)Ga-GaR(2) (1; R=CH(SiMe(3))(2)) reacts with citracinic acid by the release of two equivalents of bis(trimethylsilyl)methane and the formation of a unique oligofunctional cage compound (2). Four Ga-Ga bonds in a tetrahedral arrangement are bridged by four spacer ligands that are located on the faces of the tetrahedron and bridge the gallium atoms of three different Ga-Ga bonds. Four pyridinium groups result from the shift of one of the three acidic protons of four citracinic acid molecules to the nitrogen atoms of the aromatic rings. The N-H groups are arranged in pairs and are capable of acting as chelating acceptors for the coordination of THF molecules (2(THF)(2)) or the nitrogen atoms of 1-deazapurine (3(OEt(2))(4)). In particular, the last reaction verifies the potential applicability of this relatively water- and air-resistant acceptor compound for the generation of bioorganometallic hybrid molecules.

show abstract

Enhancement of catalytic performance by creating shell layers on sulfonic acid-functionalized monodispersed mesoporous silica spheres

Cited by 30 publications

References 25 publications

Synthesis, Characterization, and Catalytic Properties of Two Zwitterionic Hybrid SBA‐15 Mesoporous Silicas

Synthesis, Characterization, and Catalytic Properties of Two Zwitterionic Hybrid SBA‐15 Mesoporous Silicas

Chirally Functionalized Hollow Nanospheres Containing L‐Prolinamide: Synthesis and Asymmetric Catalysis

Synthesis of a Large Functional Cage Compound Based on Four GaGa Single Bonds and Its Application as an Oligoacceptor: On the Way to Bio‐Organogallium Hybrid Molecules

Contact Info

Product

Resources

About