Bifunctional Periodic Mesoporous Organosilica Research Articles

Improved catalytic performance by changing surface and textural properties of Ru supported bifunctional periodic mesoporous organosilicas in aerobic oxidation of alcohols

The catalytic activity of several supported catalysts composed of perruthenate anions incorporated into the mesochannels of a series of plugged and unplugged bifunctional periodic mesoporous organosilicas (Ru@BFPMOs) in the oxidation of alcohols were investigated.

Coupling of CO2with epoxides catalyzed by bifunctional periodic mesoporous organosilica with ionic liquid framework

Bifunctional periodic mesoporous organosilica with ionic liquid framework (BFPMO-IL) was found to be an efficient recoverable catalyst for the direct coupling of carbon dioxide with epoxides under solvent, additive and metal-free conditions.

Plugged bifunctional periodic mesoporous organosilica as a high-performance solid phase microextraction coating for improving extraction efficiency of chlorophenols in different matrices

In this study, a sensitive solid phase microextraction (SPME) coating was developed based on two kinds of plugged and non-plugged bifunctional periodic mesoporous organosilicas (BFPMO) with ionic liquid and ethyl units. The extraction efficiency of all plugged and unplugged sorbents was investigated for the extraction of chlorophenols (CPs) in water and honey samples by emphasizing the effect of different physicochemical properties. The separation and determination of the CPs was performed by gas chromatography-mass spectrometry (GC-MS). The extraction results showed that plugged BFPMO coating exhibited outstanding enrichment ability for the extraction of CPs as model analytes with different polarities. This can be attributed to a valuable hydrophobic−hydrophilic balance in the mesochanels of the plugged BFPMO, which is the result of the combination of plug technology and bridged organic groups.Low limits of detection in the range of 5–70 ng L−1, wide linearity, and good reproducibility (RSD = 8.1–10.1 % for n = 6) under the optimized extraction conditions were achieved. Finally, the BFPMOs coated fiber was successfully used for determination of CPs in real water samples. The relative recoveries for the five CPs were in the range of 92.3–104.0 %, which proved the applicability of the method.

Ionic liquid/Mn complex immobilized on phenylene based periodic mesoporous organosilica: An efficient and reusable nanocatalyst for green oxidation of alcohols

A novel bifunctional periodic mesoporous organosilica with ionic liquid and phenylene framework supported manganese (BPMO-Ph-IL/Mn) was synthesized, characterized and its catalytic application was investigated. The BPMO-Ph-IL/Mn nanocatalyst was prepared through grafting of ionic liquid on a phenylene based PMO followed by treatment with manganese nitrate. The designed BPMO-Ph-IL/Mn catalyst was characterized using FT-IR, PXRD, TEM, EDX and N2 adsorption–desorption analyses. This was used as an efficient catalyst for selective oxidation of different alcohols. The BPMO-Ph-IL/Mn catalyst was recovered and reused for at least five times without a significant decrease in its efficiency.

Magnetic yolk-shell structured methylene and propylamine based mesoporous organosilica nanocomposite: A highly recoverable and durable nanocatalyst with improved efficiency

A yolk–shell (YS) structured nanocomposite with magnetite core and methylene- and propylamine-based bifunctional periodic mesoporous organosilica (BPMO) shell (YS-Fe3O4@Am-PMO) was synthesized and employed as a powerful nanocatalyst for Knoevenagel condensation. The YS-Fe3O4@Am-PMO was synthesized via cetyltrimethylammonium bromide (CTAB) directed co-condensation of bis[(3-trimethoxysilyl)propyl]amine (BTMSPA) and bis(triethoxysilyl)methane (BTESM) around Fe3O4@SiO2 nanoparticles under basic conditions. The Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), thermal gravimetric (TG), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analyses were used to characterize this nanocomposite. The catalytic activity of YS-Fe3O4@Am-PMO was successfully studied in the Knoevenagel condensation under both thermal and ultrasonic conditions. The YS-Fe3O4@Am-PMO nanocatalyst could be magnetically recovered and reused several times with no important decrease in its performance.

Tailoring Bifunctional Periodic Mesoporous Organosilicas for Cooperative Catalysis

This paper presents a novel approach to create bifunctional periodic mesoporous organosilicas containing thiol and sulfonic acid groups (SHm/SO3Hn@PMO) by co-condensation reactions of an own design...

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.

Imidazolium-based mesoporous organosilicas with bridging organic groups for microextraction by packed sorbent of phenoxy acid herbicides, polycyclic aromatic hydrocarbons and chlorophenols.

The authors describe the preparation of two kinds of periodic mesoporous organosilicas (PMOs). The first kind is monofunctional and has a bridged alkyl imidazolium framework (PMO-IL). The other is a two-dimensional (2D) hexagonal bifunctional periodic mesoporous organosilica (BFPMO) with bridged IL-phenyl or -ethyl units. The CPMOs were utilized as highly sensitive and stable sorbents for microextraction by packed sorbent. The materials were characterized by SEM, TEM, FT-IR, and N2 adsorption-desorption analysis. The adsorption capacities of the sorbents were investigated by using phenoxy acid herbicides as model analytes. The effects of bifunctionality and type of additional surface groups (phenyl or ethyl) on the efficiency of the extraction is emphasized. Three kinds of environmental contaminants, viz. phenoxy acid herbicides (CPAs), polycyclic aromatic hydrocarbons and chlorophenols were then studied with respect to their extraction by the sorbents. The interactions between the CPAs and the sorbents were evaluated by pH-changing processes to explore the interactions that play a major role. The selectivity of the sorbents was investigated by extraction of other types of analytes of with various polarity and charge. The BFPMOs display the typical good chemical stability of silica materials. The extraction properties are much better compared to commercial silicas. This is assumed to be due to the highly ordered mesoporous structures and the different types of probable interactions with analytes. The performance of the method was evaluated by extraction of CPAs as model analytes from aqueous samples, and quantification by GC with FID detection. Under optimized conditions, low limits of detection (0.1-0.5μg.L-1) and a wide linearity (0.5-200μg.L-1) were obtained. The method was applied to the trace analysis of CPAs in farm waters and rice samples. Graphical abstract Monofunctional periodic mesoporous organosilica with bridged alkyl imidazolium frameworks and bi-functional periodic mesoporous organosilica containing bridged ionic liquids and phenyl or -ethyl, have been successfully synthesized and utilized in microextractions by packed sorbent sorbents.

Phenylene and Isatin Based Bifunctional Mesoporous Organosilica Supported Schiff-Base/Manganese Complex: An Efficient and Recoverable Nanocatalyst

A novel bifunctional periodic mesoporous organosilica supported isatin-Schiff-base/manganese complex [BPMO@ISB/Mn(II)] is prepared, characterized and its catalytic performance is investigated in the synthesis of dihydropyrano[3,2-c]chromene derivatives. The BPMO@ISB was prepared via grafting of 3-aminopropyltrimethoxysilane (APTS) on a phenylene based PMO followed by treatment with isatin. The BPMO@ISB was then reacted with Mn(NO3)2·4H2O to afford the BPMO@ISB/Mn(II) nanocatalyst. This catalyst was characterized using Fourier transform infrared (FT-IR) spectroscopy, thermal gravimetric analysis (TGA), energy-dispersive X-ray (EDX) spectroscopy, scanning electron microscopy (SEM), low angle powder X-ray diffraction (LAPXRD) analysis and transmission electron microscopy (TEM). The BPMO@ISB/Mn(II) nanocatalyst was successfully used in one-pot synthesis of 3,4-dihydropyrano[c]chromene derivatives at room temperature. In addition, the stability, recyclability and reusability of designed nanocatalyst were studied under applied conditions.

Synthesis, characterization and catalytic application of a novel ethyl and boron sulfonic acid based bifunctional periodic mesoporous organosilica

Abstract A novel ethyl and boron sulfonic acid based bifunctional periodic mesoporous organosilica [BPMO-Et-B(OSO3H)2] with dual Lewis-protic acidic sites was prepared, characterized and applied as efficient nanocatalyst for the synthesis of tetrahydrobenzo[b]pyrans. The BPMO-Et-B(OSO3H)2 was prepared by the chemical attachment of boric acid [B(OH)3] on an ethyl-based periodic mesoporous organosilica (PMO-Et) followed by treatment with chlorosulfonic acid (ClSO3H) at room temperature. This nanocatalyst was characterized using Fourier transform infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA), low-angle powder X-ray diffraction (LAPXRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis and transmission electron microscopy (TEM). The BPMO-Et-B(OSO3H)2 was shown to be a highly efficient nanocatalyst for three-component synthesis of tetrahydrobenzo[b]pyran derivatives at room temperature under solvent-free conditions. Moreover, the BPMO-Et-B(OSO3H)2 was recovered and reused at least 8 times without significant decrease in its activity.

Phenyl and ionic liquid based bifunctional periodic mesoporous organosilica supported copper: An efficient nanocatalyst for clean production of polyhydroquinolines

A novel phenyl and ionic liquid based bifunctional periodic mesoporous organosilica supported copper (Cu@BPMO-Ph-IL) is prepared, characterized and its catalytic application is developed in the clean production of polyhydroquinolines. The Cu@BPMO-Ph-IL was prepared via chemical grafting of ionic liquid groups onto phenyl-based PMO followed by treatment with copper acetate. This nanocatalyst was characterized with transmission electron microscopy (TEM), scanning electron microscopy (SEM), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTs), thermal gravimetric analysis (TGA), powder X-ray diffraction (PXRD), nitrogen-sorption and energy dispersive X-ray (EDX) analyses. This was successfully applied in the one-pot Hantzsch condensation of aldehydes, ammonium acetate, alkylacetoacetates and dimedone to prepare a set of different derivatives of polyhydroquinolines in high yields and selectivity. The catalyst was effectively recovered and reused several times without important decrease in efficiency. The recovered catalyst was also characterized with TEM analysis to study its stability and durability under applied conditions.

Simple, mono and bifunctional periodic mesoporous organosilicas for removal of priority hazardous substances from water: The case of mercury(II)

Pristine, amino monofunctionalized and amino and thiol bifunctionalized phenylene-bridged periodic mesoporous organosilicas (Ph-PMO) were synthetized by a simple methodology without any protection/deprotection steps. The Ph-PMO materials were characterized and their potential as new sorbents for Hg(II) was investigated for low-contamination scenarios. The materials have well-ordered mesostructures as confirmed by powder X-ray diffraction and transmission electron microscopy analyses. 13C and 29Si solid-state NMR confirm the amination of the phenylene bridge of the simple Ph-PMO to form the amine-functionalized PMO (NH2-Ph-PMO) and the grafting of the thiol silylated ligand to the free silanols of the NH2-Ph-PMO to obtain the bifunctional (NH2-Ph-PMO-SH). For the initial conditions tested, the bifunctional material showed excellent Hg(II) removal efficiency (98%) and Hg(II) uptake time (30min). The sorption kinetics were also investigated by three of the most studied kinetic models, and the pseudo-second-order kinetic model was the one that better described the kinetic sorption process of Hg(II) ions onto all PMO.

A novel red emitting material based on polyoxometalate@periodic mesoporous organosilica

The first lanthanopolyoxometalate-supported bifunctional periodic mesoporous organosilica (BPMO) composite is here reported. The incorporation of decatunsgstoeuropate anions ([Eu(W5O18)2]9−) within the porous channels of an ethylene-bridged TMAPS-functionalized BPMO produced a luminescent material exhibiting a strong red emission under UV irradiation. Photoluminescence studies showed an efficient energy transfer process to the lanthanide emitting center in the material (antenna effect). A significant change in the coordination environment of Eu3+ ions was observed after its incorporation into the TMAPS-functionalized material. The possible reason for this is discussed within the paper.

Bifunctional periodic mesoporous organosilicas with sulfide bridges as effective sorbents for Hg(II) extraction from environmental and drinking waters

A well-ordered two-dimensional hexagonal periodic mesoporous organosilica have been prepared with a high content of disulfide groups in the pore wall (PMO-S-S). This material was obtained by co-condensation of bis(triethoxysylilpropyl)disulfide and tetraethyl orthosilicate under acidic conditions, using non-ionic surfactant P123 as the template. In order to obtain bifunctional disulfide-bridged materials (PMO-S-S-MTTZ and PMO-S-S-MP), the PMO-S-S was modified in a second step with the organic derivatives of 5-mercapto-1-methyltetrazole (MTTZ) or 2-mercaptopyridine (MP) with sulphur and nitrogen active groups in their molecular structures. The characterization of the materials was carried out by XRD, TEM and SEM, nitrogen adsorption-desorption isotherms, 13C MAS-NMR, 29Si MAS-NMR, FTIR, elemental and thermogravimetric analysis. All prepared materials showed excellent adsorption efficiency and selectivity for Hg(II). The results confirmed the existence of additional active sulphur and nitrogen groups on the material surface, in addition to the disulfide groups of the framework, gave a significant enhancement of Hg(II) maximum adsorption capacity of the materials, being the highest Hg(II) adsorption capacity obtained 437 mg g−1 at pH 5. The prepared materials could be potential sorbents for the extraction of this heavy metal from environmental and drinking waters.

Synthesis and characterization of ionic liquid based bifunctional periodic mesoporous organosilica supported potassium carbonate as very efficient nanocatalyst for the Knoevenagel condensation

A novel ionic liquid based bifunctional periodic mesoporous organosilica supported potassium carbonate (BPMO-IL-KCO3) is prepared, characterized and its catalytic efficiency is studied in the Knoevenagel reaction. The BPMO-IL-KCO3 was prepared by chemical attachment of 1-methyl-(3-trimethoxysilylpropyl) imidazolium chloride on an ionic liquid based PMO followed by treatment with potassium carbonate under ambient temperature. This material was characterized with thermal gravimetric analysis (TGA), energy-dispersive X-ray (EDX) spectroscopy, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The BPMO-IL-KCO3 was then successfully applied as efficient base catalyst in the Knoevenagel condensation of different aldehydes with ethyl cyanoacetate and gave high to excellent yields of the corresponding coupling products. The catalyst was recovered and reused several times without significant decrease in activity and selectivity. The recovered catalyst was also analyzed with TEM and nitrogen sorption experiment to investigate structural stability and durability of the material under applied conditions.

Compressed CO2 mediated synthesis of bifunctional periodic mesoporous organosilicas with tunable porosity.

A facile and green method is proposed for the fabrication of bifunctional periodic mesoporous organosilicas (PMOs) using compressed CO2.

ChemInform Abstract: Preparation of Iron‐Containing Schiff Base and Ionic Liquid Based Bifunctional Periodic Mesoporous Organosilica and Its Application in the Synthesis of 3,4‐Dihydropyrimidinones

Abstractvia Biginelli reaction

A disposable electrochemical sensor based on bifunctional periodic mesoporous organosilica for the determination of lead in drinking waters

A new bifunctional disulfide- and tetrasulfide-bridged periodic mesoporous organosilica (PMO) with mercaptothiazoline ligand was synthesized and employed to prepare chemically modified carbon paste electrodes for Pb(II) detection in aqueous media by square wave adsorptive stripping voltammetry. To demonstrate the real interest of bifunctionalization, carbon paste electrodes were prepared with disulfide- and tetrasulfide-bridged PMO without mercaptothiazoline ligand. Results showed the importance of bifunctionalization of PMOs to improve the sensitivity for the determination of Pb(II) in water samples. To achieve the most accurate and sensitive Pb(II) measurements, optimization of the operating parameters in preconcentration and detection steps was performed. Finally, the modified carbon paste electrode prepared with bifunctional disulfide-bridged PMO with mercaptothiazoline ligand was applied to determine Pb(II) in different water samples without any pretreatment. Using this electrode, the optimal operating conditions were 120 s of electrolysis time in HCl 0.4 M. In these conditions, the voltammetric signal increased linearly with the preconcentration time from 1 to 10 min. Under optimized conditions, the linear range was 2–100 μg/L (R 2 = 0.9943) with a detection limit of 0.5 μg/L (for 5-min preconcentration time). Good reproducibility was achieved on both single and equally prepared electrodes. The accuracy of the method was validated by analysing Pb(II) in different drinking and natural water samples, with spiked recoveries in the range of 95–105 ± 10 %. The results demonstrated that the prepared electrochemical sensor exhibited selectivity, fast response time and exceptional long-time stability.

Preparation of Iron-Containing Schiff Base and Ionic Liquid Based Bifunctional Periodic Mesoporous Organosilica and Its Application in the Synthesis of 3,4-Dihydropyrimidinones.

A novel iron-containing Schiff base and ionic liquid based bifunctional periodic mesoporous organosilica (Fe@SBIL-BPMO) was prepared, characterized, and its catalytic application was developed. The SBIL-BPMO was first prepared by the grafting of 3-aminopropyltrimethoxysilane on an ionic-liquid-based PMO followed by treatment with 2-hydroxybenzaldehyde in toluene at reflux. This material was then reacted with Fe(NO3 )3 ⋅9 H2 O to afford the Fe@BPMO-SBIL nanocatalyst. The catalyst was characterized by thermogravimetric analysis, nitrogen sorption experiments, diffuse reflectance FTIR spectroscopy, low-angle powder XRD, and TEM. The Fe@SBIL-BPMO catalyst was successfully applied in the one-pot synthesis of 3,4-dihydropyrimidinone/thione derivatives under solvent-free reactions. The stability, reactivity, and reusability of the catalyst under the reaction conditions have also been investigated.

Control of plugging in bifunctional periodic mesoporous organosilica with imidazolium framework (BFPMO) via stepwise addition of silica precursors

The synthesis of novel highly ordered plugged or normal bifunctional periodic mesoporous organosilicas (BFPMOs) with variable content of bridged IL-phenyl or -ethyl units has been described.