Co-condensation Strategy Research Articles

Sub-nanometer scale tailoring of the microstructures of composite organosilica membranes for efficient pervaporation of toluene/n-heptane mixtures

Amorphous organosilica-based membranes are of enormous potential for pervaporation separation of organic mixtures, however, engineering organosilica membranes with the on-demand pore size and functionality for precise molecular sieving still remains a challenge. Herein, as a proof-of-concept, we proposed a facile and novel co-condensation strategy by pairing the biphenyl-bridged organosilica precursor (BTESBP) with another organosilica precursor (PhTES) equipped with a phenyl pendant group for efficient pervaporation of aromatic/aliphatic mixtures. It was demonstrated that the strong aromatic π-π interactions between BTESBP and PhTES as well as the steric hindrance effect of PhTES allowed the tailoring of membrane pore size at the sub-nano scale, and enhanced the accessibility of biphenyl groups to aromatic hydrocarbons. At the optimal BTESBP/PhTES mass ratio of 98/2, the resulting BTESBP/PhTES composite organosilica membrane achieved superior toluene/n-heptane pervaporation separation performance with a total flux surpassing 1 kg m−2 h−1 and a separation factor of 8–10 for a 50 wt% toluene/n-heptane feed mixture. Hopefully, this study can stimulate the rethinking of the design principles for composite organosilica membranes and the subsequent development of advanced membranes for energy-efficient pervaporation of organic mixtures.

Zirconium Containing Periodic Mesoporous Organosilica: The Effect of Zr on CO2 Sorption at Ambient Conditions

Two series of zirconium-incorporated-periodic-mesoporous-organosilica (Zr–PMO) materials were successfully prepared, via a co-condensation strategy, in the presence of Pluronic P123 triblock copolymer. The first series of Zr–PMO was prepared using tris[3-(trimethoxysilyl)propyl]isocyanurate (ICS), tetraethylorthosilicate (TEOS), and zirconyl chloride octahydrate(ZrCO), denoted as Zr-I-PMO, where I refers to ICS. The second series was synthesized using bis(triethoxysilyl)benzene (BTEE), TEOS, and ZrCO as precursors, named as Zr-B-PMO, where B refers to BTEE. Zr–PMO samples exhibit type (IV) adsorption isotherms, with a distinct H2-hysteresis loop and well-developed structural parameters, such as pore volume, pore width, high surface area, and narrow pore-size distribution. Structural properties were studied by varying the Zr:Si ratio, adding TEOS at different time intervals, and changing the amount of block copolymer-Pluronic P123 used as well as the calcination temperature. Surface characteristics were tailored by precisely controlling the Zr:Si ratio, upon varying the amount of TEOS present in the mesostructures. The addition of TEOS at different synthesis stages, notably, enhanced the pore size and surface area of the resulting Zr-I-PMO samples more than the Zr-B-PMO samples. Changing the amount of block copolymer, also, played a significant role in altering the textural and morphological properties of the Zr-I-PMO and Zr-B-PMO samples. Optimizing the amount of Pluronic P123 added is crucial for tailoring the surface properties of Zr–PMOs. The prepared Zr–PMO samples were examined for use in CO2 sorption, at ambient temperature and pressure (25 °C, 1.2 bar pressure). Zr–PMO samples displayed a maximum CO2 uptake of 2.08 mmol/g, at 25 °C and 1.2 bar pressure. However, analogous zirconium samples, without any bridging groups, exhibited a significantly lower CO2 uptake, of 0.72 mmol/g, under the same conditions. The presence of isocyanurate- and benzene-bridging groups in Zr-I-PMO and Zr-B-PMO samples enhances the CO2 sorption. Interestingly, results illustrate that Zr–PMO materials show potential in capturing CO2, at ambient conditions.

Adsorption of multi-bivalent heavy metal ions in aqueous solution onto aminopropyl-functionalized MCM-48 preparation by co-condensation

ABSTRACT In this study, we successfully synthesized aminopropyl-functionalized MCM-48 (NH2-MCM-48) using the one-pot co-condensation strategy, with the use of co-templates. Using X-ray diffraction (XRD), Fourier-transform infrared (FTIR), and scanning electron microscopy spectra (SEM), these findings proved that we bridged the amino groups on the mesoporous channel of MCM-48. Our results indicated that the maximum adsorption levels of Mn2+, Ni2+, Cu2+, Cd2+, and Pb2+ onto NH2-MCM-48 were 63.3 mg/g, 74.1 mg/g, 96.2 mg/g, 158.7 mg/g, and 322.6 mg/g, respectively. Our results demonstrate that NH2-MCM-48 could be used to remove Mn2+, Ni2+, Cu2+, Cd2+, and Pb2+ from wastewater.

Phosphonate mesoporous hybrid thin films: Synthesis of organophosphosilane by thiol-ene click chemistry and applications in formation and stabilization of silver nanoparticles

Abstract The synthesis of hybrid inorganic organic mesoporous films with pores displaying phosphonic acid functions and their use as template for Ag nanoparticles are presented here. The Photochemical radical thiol – ene addition (PRTEA) was used for the synthesis of organophosphonated thiopropyltrimethoxysilanes with either diethyl allylphosphonate (DEAP) and vinylphosphonic acid (VPA) functionalities, which quantitatively lead to two functionalizing agents with differential reactivities. Phosphonated Hybrid Mesoporous Silica Thin Films with different composition were obtained by incorporating variable amounts of the phosphonated silanes by co-condensation strategy. Structural characterization with electron microscopy, X-ray reflectometry (XRR) and small angle X-ray scattering (SAXS) in transmission mode demonstrated the synthesis of ordered mesoporous phases in all tested compositions. The chemical characteristics of the hybrid films were evaluated by Energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) showing the quantitative incorporation of the two silanes. The phosphonic groups present in the hybrid mesoporous silica thin films surface improved the adsorption of Ag (I) ion, acting as complexation sites. Silver nanoparticles (NPs) were afterwards obtained by adsorption/reduction cycles using NaBH4 as reduction agent. The obtained nanocomposites presented well distributed Ag NPs, as demonstrated by electronic microscopy and UV–visible spectroscopy. Moreover, the NPs were highly stable against oxidation when included within the functional oxides, in comparison with the pure oxide counterpart. Both phosphonated functions produced a high Ag (I) and Ag NPs loading, but the different chemistry of the phosphonates had an impact on total loading and stability of the NPs. While the free phosphonic acid presented the largest Ag (I) ion adsorption, higher chemical stability of Ag NPs was achieved for the ester protected phosphonate.

Pd-chelated 1,3,5-triazine organosilica as an active catalyst for Suzuki and Heck reactions

Design of novel functional periodic mesoporous organosilica with molecular level control finds applications in several fields of energy and environmental research including adsorption, catalysis, nanotechnology, and energy harvesting. Herein we present a melamine (1,3,5-triazine) functionalized periodic mesoporous silica (MPMO) by self-assembly of N2,N4,N6-tris(3-(triethoxysilyl)propyl)-1,3,5-triazine-2,4,6-triamine (TTET) with tetraethylorthosilicate (TEOS) via cocondensation strategy. The TTET silsesquioxane precursor was synthesized by the condensation reaction between cyanuric chloride and 3-aminopropyl triethoxysilane. The resultant MPMO material serves as an effective solid chelating agent through amine and triazine functionalities for Pd(II) to provide Pd-MPMO. The Pd-MPMO material was thoroughly characterized by a small-angle XRD, HRTEM, N2 sorption, 13C CP-MAS NMR, 29Si CP-MAS NMR, and ICP analyses. The Pd-MPMO serves as an active catalyst for CC bond formation reactions by Suzuki- and Heck cross-coupling methodologies under ligand- and cocatalyst-free conditions. Notably, the present catalytic protocol demonstrates a wide spectrum of substrate scope towards Suzuki coupling between aryl halides (I−, Br−, Cl−) and aryl boronic acids with high turn-over-number (TON) in aqueous phase under air ambience. Whereas for Heck-coupling reaction, the phenyl iodides furnished high TON than the other aryl halides. Investigation of Pd-leaching by a hot filtration test as well as reusability experiments confirms the true heterogeneous nature of present Pd-MPMO and its robustness in terms of substrate scope, catalyst stability, and durability.

One-pot co-condensation strategy for dendritic mesoporous organosilica nanospheres with fine size and morphology control

A one-pot co-condensation strategy was developed for dendritic mesoporous organosilica nanospheres with fine size and morphology control.

Clickable Multifunctional Large-Pore Mesoporous Silica Nanoparticles as Nanocarriers

Large-pore mesoporous silica nanoparticles (LP-MSNs) with defined particle size (<200 nm) are promising carrier systems for the cellular delivery of macromolecules. Ideal nanocarriers should be adaptable in their surface properties to optimize host–guest interactions; thus, surface functionalization of the nanovehicles is highly desirable. In this study, we synthesized various monofunctional LP-MSNs by incorporating different organic groups into the silica framework via a co-condensation approach. Further, we applied a delayed co-condensation strategy to create spatially segregated core–shell bifunctional LP-MSNs. Diverse particle morphologies were obtained by adding different organosilanes to the silica precursor solution. The effect of organosilanes in the co-condensation process on particle size and pore structure formation is also discussed. Surface functional groups were then used for binding stimuli-responsive linkers. These were finally exploited for copper-free click chemistry for cargo conjugatio...

Synthesis of boron-doped g-C3N4 with enhanced electro-catalytic activity and stability

Herein, we rationally designed 3D carbon nitride hierarchical architecture with an interconnected network of graphene-analogue nanosheets and doped with boron through co-condensation strategy. XPS spectra confirmed the incorporation of boron atoms in the polymeric g-C3N4, while X-ray diffraction and IR indicated the characteristic structural properties of pristine g-C3N4 and boron-doped g-C3N4 (Bx-GCN). The Bx-GCN shows promising electrocatalytic activity and stability in the reduction of p-nitrophenol according to cyclic voltammograms analysis. Additionally, the use of this metal-free, organic, semiconducting polymer as an electrocatalyst would open wide application of hybrid carbon nitride materials from both point view of economy and environment.

Mesoporous silica-based carbon dot/TiO2 photocatalyst for efficient organic pollutant degradation

Carbon dots (CD) and Ti species were assembled in the mesoporous silica matrix by a one-pot co-condensation strategy. The CD and Ti in the silica matrix were demonstrated to interact in two ways: on the one hand, part of the carbon in CD was doped into the Ti species; on the other hand, CD worked as photosensitizers for Ti species. The synergy effect between CD and Ti in the silica matrix along with the unique physical properties of the composite including ordered pore channels, large surface area and wide-range light absorption from UV to near IR made this composite be an excellent photocatalyst, as demonstrated by the photocatalytic degradation of azo dye acid orange 7. In addition to the degradation of organic pollutant, this newly developed mesoporous composite is expected to have promising applications in various areas related to environment and energy such as photoreduction of CO2 and photocatalytic H2 production.

Adsorption of Lead Ions from Aqueous Phase on Mesoporous Silica with P-Containing Pendant Groups.

Mesoporous silica materials with hydroxyphosphatoethyl pendant groups (POH-MS) were obtained by a two-step process: (1) block copolymer Pluronic P123-templated synthesis of mesoporous silica with diethylphosphatoethyl groups (DP-MS) by co-condensation of diethylphosphatoethyl triethoxysilane (DPTS) and tetraethylorthosilicate (TEOS) under acidic conditions and (2) conversion of diethylphosphatoethyl into hydroxyphosphatoethyl groups upon suitable treatment with concentrated hydrochloric acid. The DP-MS samples obtained by using up to 20% of DPTS featured hexagonally ordered mesopores, narrow pore size distribution and high specific surface area. Conversion of DP-MS to mesoporous silica with hydroxyphosphatoethyl groups (POH-MS) resulted in the enlargement of the specific surface area, total porosity, and microporosity. High affinity of hydroxyphosphatoethyl groups toward lead ions (Pb(2+)) makes the POH-MS materials attractive sorbents for lead ions, which is reflected by high lead uptake reaching 272 mg of Pb(2+) per gram of POH-MS. This study shows that the simple and effective co-condensation strategy assures high loading of P-containing groups showing high affinity toward lead ions, which is of great importance for removal of highly toxic lead ions from contaminated water.

The shape effect of PEGylated mesoporous silica nanoparticles on cellular uptake pathway in Hela cells

The shape of nanoparticles plays an important role in the interaction between cells and particles. However, the shape effect of mesoporous silica nanoparticles on the cellular uptake pathway and mechanism has not been reported. Herein, three different kinds of fluorescent mesoporous silica nanoparticles (FMSN, aspect ratio=1, 2, and 4, ca. 100nm in diameter) with similar fluorescent intensity at equivalent concentration were fabricated by a co-condensation strategy. In simulated body fluid (SBF), the PEGylated FMSN (FMSN-PEG) have higher dispersity and stability than the naked counterparts. So we chose the FMSN-PEG to research of shape effect on the cellular uptake pathway in Hela cells. We found that the uptake kinetics and pathway of three different shaped FMSN-PEG were obviously shape-dependent. The long-rod FMSN-PEG (NLR-PEG) showed higher intracellular retention amount than the short-rod FMSN-PEG (NSR-PEG) and the sphere FMSN-PEG (NS-PEG) almost over 8h. The NSR-PEG showed the lowest intracellular amount especially with prolonged incubation time. We also found that the cellular entry pathway of NS-PEG, NSR-PEG, and NLR-PEG into Hela cells was regulated by particle shape. Spherical particles preferred to be internalized via the clathrin-mediated pathway, whereas MSN with larger aspect ratios (ARs) favored to be internalized via caveolae-mediated pathway, which could explain their different uptake kinetics. Our findings may provide useful information for optimizing the nano-based drug delivery and bio-imaging systems.

A Facile Route to Prepare Organic/Inorganic Hybrid Nanomaterials by ‘Click Chemistry’

An organosilane with an alkyne group at the non-condensable end, [(2-propynylcarbamate)propyl]triethoxysilane, has been synthesized. Condensation of this organosilane with tetraethoxysilane can be achieved by a co-condensation strategy to produce silica nanoparticles with surface alkyne functionality. The size and uniformity of size distribution of the silica nanoparticles are influenced by varying the concentration of the added organosilane. The alkyne-functionalized silica nanoparticles are coupled directly with azide-modified polymers by 'click chemistry' to yield organic-inorganic hybrid nanomaterials.

Multiple Core−Shell Functionalized Colloidal Mesoporous Silica Nanoparticles

The selective functionalization of the inner and outer surfaces of colloidal mesoporous silica (CMS) nanoparticles with different trialkoxysilanes, following a newly developed delayed co-condensation approach, results in bifunctional CMS. Complementary CMS nanoparticles were prepared with two different functional groups located either on the outer shell or in the inner core of the particle. The identification and localization of the functional groups was achieved by means of different techniques including zeta potential, nitrogen sorption measurements, and fluorescence spectroscopy. This last technique was applied to fluorescein isothiocyanate (FITC)-labeled CMS featuring aminopropyl functional groups on the periphery or the internal pore surface of the particles. Fluorescence quenching experiments were carried out with dodecanethiolate-stabilized gold nanoparticles having a diameter greater than the pore size of the CMS. It could be shown that fluorescence quenching occurs only when the FITC is positioned on the outer surface of the CMS nanoparticles, whereas no quenching was observed for FITC located in the inner core of the nanoparticle. These results clearly confirm the controlled localization of the aminopropyl groups in the nanometer space of the CMS particles. Our approach thus offers the opportunity to synthesize, in a novel multistep co-condensation strategy, various bifunctional mesoporous nanoparticles with controlled localization of different functional groups in the inner core or on the outer shell of the nanoparticle.

Adsorption of phosphate and nitrate anions on ammonium-functionnalized mesoporous silicas

Surface modified mesostructured silica materials represent potential adsorbents offering an opportunity to remediate several important water pollutants. In the present work, ammonium-functionnalized MCM-41, MCM-48 and SBA-15 mesoporous silica materials were synthesized via post-synthesis grafting and co-condensation. Their efficiency to remove nitrate and phosphate anions in aqueous solutions was investigated. The adsorbent materials showed high adsorption capacities reaching 46.5 mg NO 3 − /g and 55.9 mg H2PO 4 − /g under the operating conditions explored. The mesoporous silica materials functionalized via post-synthesis grafting method exhibited higher performances in terms of percentage pollutant removal and adsorption capacities if compared to their analogs synthesized according to the co-condensation strategy.