One-pot Co-condensation Method Research Articles

Enantioselective Oral Absorption of Molecular Chiral Mesoporous Silica Nanoparticles.

Inspired by the unique pharmacological effects of chiral drugs in the asymmetrical body environments, it is assumed that the chirality of nanocarriers is also a key factor to determine their oral adsorption efficiency, apart from their size, shape, etc. Herein, l/d-tartaric acid modified mesoporous silica nanoparticles (l/d-CMSNs) are fabricated via a one-pot cocondensation method, and focused on whether the oral adsorption of nanocarriers will be benefited from their chirality. It is found that l-CMSN performed better in the sequential oral absorption processes, including mucus permeation, mucosa bio-adhesion, cellular uptake, intestinal transport and gastrointestinal tract (GIT) retention, than those of the d-chiral (d-CMSN), racemic (dl-CMSN), and achiral (MSN) counterparts. The multiple chiral recognition mechanisms are experimentally and theoretically demonstrated following simple differential adsorption on biointerfaces, wherein electrostatic interaction is the dominant energy. During the oral delivery task, l-CMSN, which is proven to be stable, nonirritative, biocompatible, and biodegradable, is efficiently absorbed into the blood (1.72-2.05-fold higher than other nanocarriers), and helps the loaded doxorubicin (DOX) to achieve better intestinal transport (2.32-27.03-times higher than other samples), satisfactory bioavailability (449.73%) and stronger antitumor effect (up to 95.43%). These findings validated the dominant role of chirality in determining the biological fate of nanocarriers.

Preparation of HKUST-1 functionalized porous silica crosslinked sodium alginate composite: Efficient reduction of 4-nitrophenol to 4-aminophenol

In this paper, sodium alginate crosslinked porous silica carrier (SA-SiO2) was introduced by one-pot co-condensation method, and Cu2+ was adsorbed on the carrier by –COOH to in-situ synthesized composite materials (HKUST-1@SA-SiO2). A series of characterizations were carried out by FT-IR, BET, XRD, XPS, SEM, and TEM. The results showed that the carrier SA-SiO2 was successfully cross-linked, HKUST-1 was successfully surface functionalized and the composites was spongy with pores. The catalytic activity and reusability of the compound HKUST-1@xSA-SiO2 were investigated for the reduction of 4-nitrophenol to 4-aminophenol. Among them, HKUST-1@0.15SA-SiO2 had the best catalytic performance and the conversion rate constant was 0.45 min−1, which was better than that of the post-synthesis method. Its catalytic activity did not decrease significantly after five cycles.

In-situ synthesis of metal-organic framework embedded in ordered mesoporous silica functionalized with carboxyl groups for 4-nitrophenol to 4-aminophenol

Herein, the –COOH functionalized ordered mesoporous silica (OMS-C) was successfully synthesized using 3-phosphonopropionic acid as a functionalized reagent via one-pot co-condensation method. Then Cu2+ ions were adsorbed by the –COOH groups present on the OMS surface. Finally, the composite material (MOF-199@OMS-C) functionalized by Metal-Organic Framework (MOF-199) was in-situ prepared through the Cu2+ ions adsorbed by the OMS-C. The experimental results of N2 adsorption–desorption, low-angle XRD, and TEM showed that MOF-199@OMS-C composites possessed an ordered 2D hexagonal mesoporous structure, high specific surface area and the formation of MOF-199 in the pore of OMS-C. Moreover, FT-IR, Raman, XPS, and TG analysis demonstrated the carboxylation on the surface of OMS, successful synthesis, and immobilization of MOF-199 within the pores of OMS-C through the –COOH of OMS, as well as the interaction between OMS-C and MOF-199. The MOF-199@OMS-C composites exhibited good catalytic activity in the reduction reaction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The apparent kinetic constant of the reduction reaction of 4-NP was 0.26 min−1 under the optimum reaction condition. The MOF-199@OMS-C composites prevented the loss and structural damage of MOF-199, and its catalytic activity even remained stable after 4 cycles. In addition, the kinetic curves of reduction reaction of 4-NPs were consistent with first-order kinetics.

Phosphotungstic acid and propylsulfonic acid bifunctionalized ordered mesoporous silica: A highly efficient and reusable catalysts for esterification of oleic acid

In phosphotungstic acid aqueous solution, the ordered mesoporous silica molecular sieve (HPW/OMS-SO3H) simultaneously functionalized by phosphotungstic acid (HPW) and propyl sulfonic acid groups (-pr-SO3H) was successfully prepared via a one-pot co-condensation method. The skeleton of the materials was formed based on the simultaneous hydrolysis and co-condensation of 3-mercaptopropyltriethoxysilane (MPTES) and tetraethoxysilane (TEOS) using in situ oxidation of the thiol groups to sulfoacid groups with H2O2. The materials with an ordered 2D hexagonal mesoporous structure and a high specific surface area were confirmed by the results of small-angle XRD, N2 adsorption–desorption, and TEM. The spectroscopy of FT-IR, UV–Vis DRS, XPS, and Raman indicated that the active component of HPW and propylsulfonic acid groups successfully immobilized on the OMS support and a strong interaction existed among silicon hydroxyl and propylsulfonic acid groups with HPW. The esterification reaction of oleic acid with methanol to produce biodiesel over prepared catalyst showed excellent catalytic activity due to the synergistic effect between the HPW and propylsulfonic acid groups. The biodiesel yield of 95.3% was obtained by 0.3HPW/OMS-SO3H-5 catalyst under the optimum reaction conditions. The catalytic performance was not reduced significantly even after five cycles reused, because the strong interaction prevented acid-active component loss from the support. The activation energy of the reaction by the 0.3HPW/OMS-SO3H-5 materials was investigated, which obeyed the first-order kinetics.

Multifunctional periodic mesoporous benzene-silicas for evaluation of CO2 adsorption at standard temperature and pressure

Abstract Bi-functional periodic mesoporous organosilicas (PMOs) embedded with phenylene- and isocyanurate-bridging groups have been synthesized by a one-pot co-condensation method using 1,4-bis(triethoxysilyl)benzene and tris[3-(trimethoxysilyl)propyl]isocyanurate precursors in the presence of a poly(ethylene oxide)-poly( dl -lactic acid-co-glycolic acid)-poly(ethylene oxide) (PEO-PLGA-PEO) triblock copolymer named LGE54 under acidic conditions. Block copolymer template has been removed by solvent-extraction to get the template-free PMO whereas PLGA block chains from the copolymer template were also removed selectively by thermal treatment at 250 °C retaining PEO chains inside the silica framework. Furthermore, the bi-functional PMO and tri-functional PEO containing PMOs were modified with N-[3-(trimethoxysilyl)propyl]ethylenediamine to prepare amine-coated PMOs on the pore surface. The bi-, tri-, and tetra-functional PMO samples have been thoroughly characterized using small angle X-ray scattering (SAXS) and nitrogen adsorption isotherms to resolve the presence of ordered mesostructure and surface area of the PMOs. Also, solid-state 13C- and 29Si CP-MAS NMR studies have been performed to investigate significant chemical linkages from amine-containing modifiers and poly(ethylene oxide) group inside and on the surface of PMO samples. Scanning electron microscopic (SEM), elemental analysis, and thermogravimetric analysis (TGA) have been carried out to obtain the morphology, elemental percentage and thermal stability of the multi-functional PMO samples, respectively. CO2 capture has been investigated on multi-functional PMO samples at 25 °C and 1 atm using a mixed flow by 3:2 vol ratio of CO2 and N2 gas. Amine-functionalized PMO has shown significantly higher amount of CO2 uptake than those obtained using PMO itself and the respective PMOs modified with different functionalities.

Enhanced adsorption of steroid estrogens by one-pot synthesized phenyl-modified mesoporous silica: Dependence on phenyl-organosilane precursors and pH condition

In this study, the phenyl-modified mesoporous materials were successfully synthesized using phenyl-organosilanes (trimethoxyphenylsilane and triethoxyphenylsilanea) by one-pot co-condensation method for the removal of estrone (E1), 17β-estradiol (E2), and 17α-ethinyl estradiol (EE2). Both the triethoxyphenylsilane-modified material (20%EtPh-MCM-41) and trimethoxyphenylsilane-modified material (20%MePh-MCM-41) could rapidly achieve equilibrium in 30 min at low adsorbent dosage of 0.025 g L−1. But the different hydrolysable groups of trimethoxyphenylsilane and triethoxyphenylsilane led to the discrepancies in physicochemical properties of the 20%EtPh-MCM-41 and 20%MePh-MCM-41, and thus affected adsorption performance. The 20%EtPh-MCM-41 exhibited the faster estrogen adsorption rates expressed in pseudo-second-order kinetic constant than the 20%MePh-MCM-41 due to the more hydrophobicity. Conversely, the 20%MePh-MCM-41 had much more estrogen adsorption capacities than the 20%EtPh-MCM-41 because of the more available adsorption sites. The addition of the phenyl-organosilane improved estrogen adsorption by π-π and hydrophobic interactions, and the Langmuir-model-based maximum adsorption amounts could reach 99.02, 83.47, and 53.60 mg g−1 for EE2, E2, and E1, respectively. But excessive concentration of phenyl-organosilane decreased adsorption capacities due to poor pore structure. Alkaline solution, which induced estrogen deprotonation and negative surface charge of absorbents, inhibited estrogen adsorption by electrostatic repulsion and the decreased hydrophobic interaction, but acidic and neutral solutions, ionic strength, and humic acid did not significantly affect estrogen removal. This work not only showed the high potential of trimethoxyphenylsilane-modified MCM-41 used in water purification for steroid estrogens, but also demonstrated the suitable selection of organosilane precursors was key in producing favorable materials with designed functionality.

Propyl–SO3H functionalized SBA-15: Microwave-mediated green synthesis of biologically active multi-substituted imidazole scaffolds

Propylsulfonic acid functionalized Santa Barbara Amorphous-15 (SBA-15–Pr–SO3H) catalyst has been synthesized using a surface modification of mesoporous SBA-15 via the one-pot co-condensation method. The synthesized SBA-15–Pr–SO3H has been characterized by peculiar characterization techniques such as small- and wide-angle XRD, SEM–EDX, TEM, TG–DTA, acidity, FT-IR, Py-FT-IR and BET surface area analysis. The catalytic activity of synthesized catalyst has been studied towards solvent-free MW irradiation for the green and rapid synthesis of multi-substituted imidazoles, [2,4,5-triphenyl-1(H)-imidazole (tri-imidazole) and 1-benzyl-2,4,5-triphenyl-1H-imidazole (tetra-imidazole)]. The SBA-15–Pr–SO3H catalyst was found to be an efficient and recyclable solid acid catalyst and this solvent-free MW protocol afforded products in good to excellent yields of both, tri and tetra imidazoles (> 95%) within shorter reaction time (3 min) at 600 W as compared to the SBA-15 and other existing protocols. The applicability of this protocol was further explored by conducting the experiments in the presence of varied solvents and substituted aldehydes to generate a library of both, tri- and tetra-imidazole scaffolds. The catalyst was found to be reusable up to several runs without loss of its catalytic activity. This report allows the rapid and scalable access to a variety of multi-substituted imidazoles using SBA-15–Pr–SO3H, as heterogeneous catalyst. SBA-15–Pr–SO3H catalyzed solvent-free MW assisted green synthesis of multi-substituted imidazoles via MCRs.

Speciation analysis of chromium by carboxylic group functionalized mesoporous silica with inductively coupled plasma mass spectrometry

Carboxyl-group functionalized mesoporous silica (CFMS) prepared by one-pot co-condensation method was employed for the solid phase extraction (SPE) of chromium species for the first time. A new approach of SPE coupled to inductively coupled plasma mass spectrometry (ICP-MS) was thus established for the speciation of chromium in environmental water samples. The influences of pH, volume of sample, extraction time, amount of adsorbent, elution conditions, co-existing ions and adsorption capacity were investigated on adsorption or elution of chromium species. Cr(VI) was not retained on the CFMS material in the pH range of 1.0–9.0, while Cr(III) was quantitatively adsorbed at pH 5.0–9.0. The captured Cr(III) was enriched by using 1.5 mol L−1 HNO3 as elution solvent and detected by ICP-MS. Under the optimized SPE conditions, the maximum adsorption capacity of the CFMS for Cr(III) was 57.67 mg g−1 and the enrichment factor was 25, with the detection limit (LOD) of 0.02 μg L−1. The proposed protocol has been successfully applied to chromium speciation in rain, lake and river water samples, which exhibited a prospect in field separation and enrichment of chromium species in environmental waters.

Carboxylic acid Functionalized Cage-Type Mesoporous Silica FDU-12 as Support for Controlled Synthesis of Platinum Nanoparticles and Their Catalytic Applications.

Carboxylic acid functionalized 3D cage-type mesoporous silica FDU-12 with high surface area and pore volume was synthesized by a one-pot co-condensation method and used as support to synthesize Pt nanoparticles (NPs). The uniformly distributed COOH groups in the cage can control the growth of Pt NPs with high dispersion (Pt@CF-12). Pt@CF-12 was used as catalyst for the hydrolysis of ammonia borane to generate H2 and for the reduction of 4-nitrophenol to 4-aminophenol. The catalyst exhibits higher catalytic activity (H2 generation rate of 17.8 L min-1 ) and lower activation energy of 30.67 kJ mol-1 compared with other Pt-based silica catalysts due to the small size of the Pt NPs (3.5 nm) and cage-type porous structure of the support, which allowed easy diffusion of reactants. Pt@CF-12 has excellent durability, since the support prevented NP aggregation and leaching of NPs during catalysis. Pt@CF-12 can convert 93 % of 4-nitrophenol to 4-aminophenol within 10 min.

One-step synthesis, characterization and oxidative desulfurization of 12-tungstophosphoric heteropolyanions immobilized on amino functionalized SBA-15

Keggin-type 12-tungstophosphoric [PW12O40]3− heteropolyanions were successfully immobilized onto mesoporous material surface of SBA-15 functionalized using the (3-aminopropyl)triethoxysilane (APTES) synthesized by one-pot co-condensation method, also called one-step synthesis. The synthesized PW−-NH3+-SBA-15 catalyst was characterized by XRD, N2 adsorption–desorption, FT-IR, TGA, SEM, TEM, EDS, XPS methods. The results indicated that ordered hexagonal mesostructure for SBA-15 support was still maintained after being functionalized with amine groups, while the specific surface area of SBA-15 was decreased. The active species of phosphotungstic acid H3PW12O40 (HPW) retained its Keggin structure of the heteropolyanions on the amine-modified SBA-15. The PW−–+H3N–SBA–15 catalyst exhibited a high catalytic activity for oxidative desulfurization process of sulfur-containing model fuel. The dibenzothiophene (DBT) conversion of almost 100% was achieved with reaction conditions of 40 mg of catalyst dosage, 2 mL of hydrogen peroxide, 90 °C of reaction temperature, and 120 min of reaction time.

Preparation and Photocatalytic Activity of Titanium Dioxide-organosilicone-Heteropolyacid Photocatalysts

TiO2-organosilicone based hybrid catalysts functioned by Keggin-type heteropolyacid, TiO2-Si (Et)Si-H3PW12O40, were prepared via one-pot co-condensation method in the presence of a triblock copolymer surfactant (F127). The materials were well characterized by FT-IR, UV-vis DRS spectroscopy methods, and X-ray diffraction analysis to confirm the hybrid structure, to investigate correlation among TiO2-organosilicone matrix and H3PW12O40. Phtocatalytic tests show that, with a little amount of organosilicone and hybridization, the composite exhibits higher photocatalytic activity when decomposing the Rhodamine B ( RhB ) than anatase TiO2.

Efficient cyclohexyl acrylate production by direct addition of acrylic acid and cyclohexene over SBA-15-SO3H

A set of propysulfonic acid modified mesostructured silica materials (SBA-15-SO3H) were prepared by a convenient one-pot co-condensation method. Samples were characterized by XRD, FT-IR, Py-FTIR, N2 adsorption–desorption, elemental analysis and acid–base titration. The catalysts exhibited excellent activities and selectivities for addition esterification of acrylic acid and cyclohexene. The highest catalytic activity (82.8 %) and selectivity (92.6 %) were obtained over SBA-15-SO3H (15 %). The efficient catalytic performance of SBA-15-SO3H (15 %) was attributed to the high surface area, proper mesopore texture and presence of sulfonic acid groups in its structure. SBA-15-SO3H catalyst was easily separated and recycled with high stability.

Preparation and Photocatalytic Activity of Heteropolyacid Supported on Titanium Dioxide Photocatalysts

TiO2-based hybrid catalysts functioned by Keggin-type heteropolyacid, H3PW12O40/ TiO2, were prepared via one-pot co-condensation method in the presence of a triblock copolymer surfactant (F127). The materials were well characterized by FT-IR, UV-vis DRS spectroscopy methods, and X-ray diffraction analysis to confirm the structural integrity of the Keggin unit in the hybrid materials, to investigate correlation between TiO2 matrix and H3PW12O40. Phtocatalytic tests show the composite exhibits higher photocatalytic activity to decompose the Rhodamine B ( RhB ) than anatase TiO2.

Extinction property of Au/SiO<sub>2</sub> nanocomposite

Ordered mesoporous silica thin films were prepared by one-pot co-condensation method by the surfactants Brij56, P123 and F127. They were used in template synthesis of gold nanoparticles, and three kinds of Au/SiO₂ nanocomposites were obtained. The absorption spectra measured by spectrophotometer show that the extinction property of nanocomposites would be affected by their mesostructure. The experimental results show that the size of gold nanoparticles will increase and nanocomposite’s extinction spectrum will undergo a red-shift while the dipping time is increased. It was analyzed by the Maxwell-Garnett (MG) theory with a simple model of the nanocomposite. The simulative results gave a qualitative explanation of the difference of the extinction property between different kinds of nanocomposites. By regulating the dipping time or choosing a proper surfactant during the preparation of Au/SiO₂ nanocomposite, we may control its extinction property.

Mesoporous titania–silica composite from sodium silicate and titanium oxychloride. Part II: one-pot co-condensation method

Mesoporous titania–silica composite with large primary particles and homogeneous dispersion of Ti in the silica matrix were synthesized by the sol–gel method via a one-pot co-condensation method using cetyltrimethylammonium bromide (CTAB) as a structure-directing agent. Freshly prepared titanium oxychloride (TiOCl2, titania precursor that is relatively stable) and sodium silicate were used as titania and silica precursors (at the initial ratio of Ti:Si = 1), respectively. The final products were obtained after removing the template by calcination and had overall ratio of Ti:Si = 2:3 (based on EDS and XRF analyses). Other characterization techniques employed include FE-SEM, TEM, FT-IR, DTGA, and nitrogen physisorption studies. The textural properties of the products were highly influenced by the molar concentration of CTAB. Materials with large primary particles (submicrometer-scale dimensions) were obtained at higher concentrations of CTAB (1.7 wt%). The porosities of the templated material were highly reduced compared to that of the untemplated material, emphasizing the influence of Ti loading in the silica matrix. Both pore size and surface area increased at a calcination temperature of 550 °C. The DTGA result showed that the composites exhibited elevated thermal stability (up to 900 °C). In summary, mesoporous titania–silica composite with desirable properties were developed via the proposed method using a relatively inexpensive silica precursor.

A fluorescent sensor array based on ion imprinted mesoporous silica

We report an ion imprinted mesoporous silica based fluorescence turn-on sensor array for discrimination of metal ions. A novel fluorescent functional monomer containing an 8-hydroxyquinoline (8-HQ) moiety in combination with one-pot co-condensation method was employed to prepare fluorescent ion imprinted mesoporous silica. The imprinted materials for Zn 2+ and Cd 2+ as well as a control blank non-imprinted material (NIM) were synthesized. With the covalently anchored organic fluorophore in the inorganic mesoporous silica matrix, the binding of metal ions to the imprinting site was directly transformed into fluorescence signals. Both the imprinted materials displayed faster binding kinetics toward metal ions than NIM. Apparent binding constants (adsorption constants) for the materials with the metal ions in water were determined by a Langmuir-type analysis of the spectrofluorimetric titration data. The sensor array composed of the three materials allows discriminating the two template metal ions (Zn 2+ and Cd 2+) plus three non-template metal ions (Mg 2+, Ca 2+ and Al 3+) at two different concentrations. This work proves that using a simple fluorescent receptor can provide a pattern based fluorescent sensing system by taking advantage of the imprinting effect.

Transesterification of soybean oil to biodiesel catalyzed by mesostructured Ta2O5-based hybrid catalysts functionalized by both alkyl-bridged organosilica moieties and Keggin-type heteropoly acid

A series of Ta2O5-based hybrid catalysts functionalized by both alkyl-bridged organosilica fragments and the Keggin-type heteropoly acid, Ta2O5/Si(R)Si-H3PW12O40 (R = –CH2CH2- or –C6H4–), were prepared via a one-pot co-condensation method in the presence of a triblock copolymer surfactant (P123). The materials were well characterized by spectroscopy methods, X-ray diffraction analysis, transmission electron microscopy, and nitrogen physisorption measurement to confirm the structural integrity of the Keggin unit and alkyl-bridged organosilica units in the hybrid materials, to investigate the interaction between the Ta2O5 matrix and the organic or inorganic functionalities, and to test the mesostructure, morphology, and porosity of the materials. The materials were subsequently utilized as environmentally-friendly solid acid catalysts in the transesterification of soybean oil (containing 20 wt% myristic acid) with methanol to produce fatty acid methyl esters under atmosphere refluxing. Compared with bulk H3PW12O40 and alkyl-free H3PW12O40/Ta2O5, as-prepared Ta2O5/Si(R)Si-H3PW12O40 hybrid materials with suitable concentrations of bridging alkyl groups exhibited higher reactivity toward the target reaction. This enhanced acid-catalytic reactivity after the introduction of both acidic and hydrophobic functionalities within the Ta2O5 matrix is discussed. Finally, the reusability of the hybrid materials was evaluated through three catalytic runs.