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Pascal Van Der Voort - One of the best experts on this subject based on the ideXlab platform.
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lanthanide grafted bipyridine Periodic Mesoporous Organosilicas bpy pmos for physiological range and wide temperature range luminescence thermometry
2020Co-Authors: Anna M Kaczmarek, Shinji Inagaki, Yoshifumi Maegawa, Anatolii Abalymov, Andre G Skirtach, Pascal Van Der VoortAbstract:2,2'-Bipyridine is the most widely used chelating ligand for developing metal complexes in coordination and supramolecular chemistry. Here, we present a series of three bipyridine Periodic Mesoporous Organosilicas (BPy-PMOs) grafted with lanthanide β-diketonate complex for the purpose of obtaining thermochromic materials, which can be employed as ratiometric temperature sensors. Such thermometers are based on the ratio of two emission intensity peaks and are not affected by factors such as alignment or optoelectronic drift of the excitation source and detectors. Three thermometric systems are studied: Dy-Dy, Tb-Sm, and Tb-Eu with the first two showing very attractive performance. For the first two systems, some of the best reported to date relative sensitivities are observed. In the BPy-PMO@Dy(acac)3 system, it is very unusual that the 4I15/2→ 6H15/2 transition is already occupied at low temperature such as 200 K, which influences its thermometric behavior. The Tb-Sm shows excellent performance in the physiological range and when suspended in water. We have additionally confirmed that the BPy-PMO hybrid materials lack toxicity to human cells, proving them very promising candidates for biomedical thermometric applications.
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tailoring bifunctional Periodic Mesoporous Organosilicas for cooperative catalysis
2020Co-Authors: Dolores Esquivel, Pascal Van Der Voort, Juan Amarogahete, Noelia Caballerocasero, Cesar Jimenezsanchidrian, Jose Rafael Ruiz, Soledad Rubio, Francisco J RomerosalgueroAbstract: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...
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functionalized Periodic Mesoporous Organosilicas from metal free catalysis to sensing
2019Co-Authors: Laurens Bourda, Himanshu Sekhar Jena, Rik Van Deun, Anna M Kaczmarek, Pascal Van Der VoortAbstract:In this work a widely usable post-modification route for Periodic Mesoporous Organosilicas (PMOs) was developed. Using the developed method, two diverse ligands, picolinic acid (Pic) and 4,4′,4′′,4′′′-porphyrin-5,10,15,20-tetrayltetrabenzoic acid (Porph), were successfully covalently coupled onto the PMO material and well-characterized. Both obtained materials show high BET surface areas (565 m2 g−1 for Pic@PMO, 483 m2 g−1 for Porph@PMO and 548 m2 g−1 for the unmodified PMO) and pore sizes (5.1 nm). The materials were subsequently tested for their catalytic activity in the cycloaddition of epoxide and CO2, a frequently studied carbon capture and utilization reaction. Interestingly, both materials showed very good reactivity (with conversions of up to 90%) as metal free heterogeneous catalysts and proved to be perfectly stable in recyclability and aging tests. Moreover, by (co-)grafting Eu3+ and Tb3+ ions onto Pic@PMO and Yb3+ ions onto Porph@PMO a strong emission was observed in the visible and near-infrared (NIR) range, respectively. Eu,Tb@Pic@PMO showed potential for use as a temperature sensor in the physiological range (a maximum Sr value of 2.11 %K−1 was obtained at 273 K), while Yb@Porph@PMO could efficiently be excited within the human tissue penetrating window showing characteristic Yb3+ luminescence (with decay times of around 10 μs). These findings prove that simple modifications of this PMO can provide smart materials for very diverse applications.
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Periodic Mesoporous Organosilicas as porous matrix for heterogeneous lyophobic systems
2018Co-Authors: Andrey Ryzhikov, Pascal Van Der Voort, Els De Canck, Jean T Daou, Habiba Noualia, Joel Patarin, Judith Ouwehand, Sander Clerick, Johan A MartensAbstract:Periodic Mesoporous Organosilicas (PMO) have been studied for the first time as a porous matrix for heterogeneous lyophobic systems (HLS) for absorption and storage of mechanical energy by high pressure intrusion extrusion of electrolyte solutions. It has been shown that the intrusion of LiCl aqueous solutions in ethane bridged PMO material is irreversible that corresponds to a bumper behavior. The intrusion pressure increases strongly with the salt concentration - from 13 MPa for 5 M LiCl aqueous solution to 37 MPa for 20 M one. Such a pressure rise of 2.8 times is the highest observed for HIS based on Mesoporous materials. Due to high intruded volume (0.63-0.72 mL/g) specific absorbed energy achieves 27 J/g, which is close to the best values ever obtained for HLS based on zeosils and Mesoporous silica. The characterization shows that after the intrusion extrusion experiments the ordered pore arrangement largely stays intact, but a slight increase of the mesopore volume is observed.
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Designing advanced functional Periodic Mesoporous Organosilicas for biomedical applications
2014Co-Authors: Dolores Esquivel, Pascal Van Der Voort, Francisco J. Romero-salgueroAbstract:Periodic Mesoporous Organosilicas (PMOs), reported for the first time in 1999, constitute a new branch of organic-inorganic hybrid materials with high-ordered structures, uniform pore size and homogenous distribution of organic bridges into a silica framework. Unlike conventional Mesoporous silicas, these materials offer the possibility to adjust the surface (hydrophilicity/hydrophobicity) and physical properties (morphology, porosity) as well as their mechanical stability through the incorporation of different functional organic moieties in their pore walls. A broad variety of PMOs has been designed for their subsequent application in many fields. More recently, PMOs have attracted growing interest in emerging areas as biology and biomedicine. This review provides a comprehensive overview of the most recent breakthroughs achieved for PMOs in biological and biomedical applications
Geoffrey A. Ozin - One of the best experts on this subject based on the ideXlab platform.
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Water Repellent Periodic Mesoporous Organosilicas
2011Co-Authors: Wendong Wang, Daniel Grozea, Sandeep Kohli, Douglas D. Perovic, Geoffrey A. OzinAbstract:This paper demonstrates for the first time thermally induced gradual hydrophobization, monitored quantitatively by ellipsometric porosimetry, of four prototypical Periodic Mesoporous Organosilicas (PMOs) that are tailored through materials chemistry for use as low-dielectric-constant (low k) materials in microprocessors. Theoretical aspects of this quantification are briefly discussed. A comparison of structural, mechanical, dielectric, and hydrophobic properties of ethane, methane, ethene, and 3-ring PMOs is made. Particularly, ethane, methane, and 3-ring PMOs show impressive water repellency at post-treatment temperatures as low as 350 °C, with corresponding Young's modulus values greater than 10 GPa and k values smaller than 2, a figure of merit that satisfies the technological requirements of future generation microchips.
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challenges and advances in the chemistry of Periodic Mesoporous Organosilicas pmos
2005Co-Authors: William J Hunks, Geoffrey A. OzinAbstract:The merger of materials synthesis, organic synthesis, and supramolecular chemistry has lead to a plethora of hybrid organic–inorganic materials with control over the molecular organization, nanoscale Periodicity, and macroscopic morphology. Self-assembly of polymeric precursors can be directed by micelle templates, or through microphase separation of block copolymers. This has provided a pathway to new materials whose hierarchical structure determines material properties and function. Periodic Mesoporous Organosilicas (PMOs), which are composed of bridge-bonded silsesquioxanes organized into a Mesoporous architecture, have emerged as promising materials for nanotechnology applications. This article provides an overview of PMOs and describes the challenges, problems and our predictions for the future of these intriguing solid-state materials.
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single source precursors for synthesizing bifunctional Periodic Mesoporous Organosilicas
2005Co-Authors: William J Hunks, Geoffrey A. OzinAbstract:A new class of bifunctional Periodic Mesoporous Organosilicas (PMOs) composed of organosilicate building blocks with two different silicon sites have been synthesized from the single-source bifunctional organosilica precursors tris(triethoxysilyl-ethyl)ethoxysilane and bis(triethoxysilylethyl)diethoxysilane, respectively denoted MT 3 -PMO and DT 2 -PMO. The synthesis of these PMOs is achieved by the co-assembly of a triblock-copolymer Pluronic P123 template with the bifunctional organosilica precursor under acid-catalyzed and inorganic-salt-assisted conditions. After template removal through solvent extraction, the MT 3 -PMO and DT 2 -PMO so obtained show well-ordered mesopores and display large pore diameters (6-7 nm) and pore volumes (0.6-0.8 cm 3 g - 1 ) with a narrow pore-size distribution and high surface areas (700-800 m 3 g - 1 ).
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Hybrid Periodic Mesoporous Organosilicas
2005Co-Authors: Wesley Whitnall, Tewodros Asefa, Geoffrey A. OzinAbstract:In this study we report the synthesis of a new class of materials called hybrid Periodic Mesoporous Organosilicas (HPMOs). By coupling a silsesquioxane precursor through at least two chemical linkages to the mesopore walls of a pre-existing Periodic Mesoporous silica (PMS) or Periodic Mesoporous organosilica (PMO). Many of the problems of a conventional PMO material can be avoided while ensuring efficient use of the bridging organic functional groups of the silsesquioxane. We demonstrate this concept for PMS by anchoring various silsesquioxanes, such as ethene and ethane silsesquioxanes, to the mesopore walls of the PMS. The addition of anchored silsesquioxane monolayers and multilayers to the mesopore walls also allows for the strict control of the diameter of the mesopore as well as the mesopore wall thickness in the final HPMO material. Additionally it is shown that having the silsesquioxane located solely on the surface of the mesopores in HPMOs gives increased chemical accessibility of the organic bridge-bonded moiety when compared with their PMO counterparts containing the bridge-bonded organic both on the surface and within the pore walls.
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Periodic Mesoporous Organosilicas with phenylene bridging groups 1 4 ch2 nc6h4 n 0 2
2004Co-Authors: William Hunks J And, Geoffrey A. OzinAbstract:Periodic Mesoporous Organosilicas (PMOs) were prepared by polymerizing phenylene-bridged silsesquioxane precursors containing an incremental increase in methylene spacers [1,4-(CH2)nC6H4 (n = 0−2)] in combination with polyoxyethylene(10) cetyl ether (Brij 56) oligomers as structure-directing species under acid catalysis. Surfactant templates were removed from the nanoporous inorganic−organic hybrids using acidified ethanol extractions. Mesoporous Organosilicas were characterized by powder X-ray diffraction, nitrogen gas sorption, 13C and 29Si solid-state NMR, scanning and transmission electron microscopy, and thermogravimetric analysis. Organosilica materials formed uniform arrays of 2D-hexagonal mesopores with pore diameters ranging from 2 to 3 nm and corresponding surface areas of 750−1200 m2g-1. Addition of two methylene groups to the phenylene bridge resulted in a substantial decrease in the pore size, surface area, and pore volume. The thermal stability of the materials decreases in the following ord...
Hsienming Kao - One of the best experts on this subject based on the ideXlab platform.
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synthesis of highly phosphonic acid functionalized benzene bridged Periodic Mesoporous Organosilicas for use as efficient dye adsorbents
2014Co-Authors: Juti Rani Deka, Chialing Liu, Tzuhua Wang, Weichieh Chang, Hsienming KaoAbstract:Abstract Periodic Mesoporous Organosilicas (PMOs) with benzene bridging groups in the silica wall were functionalized with a tunable content of phosphonic acid groups. These bifunctional materials were synthesized by co-condensation of two different organosilane precursors, that is, 1,4-bis(triethoxysilyl)benzene (BTEB) and sodium 3-(trihydroxysilyl)propyl methyl phosphate (SPMP), under acidic conditions using nonionic surfactant Brij-S10 as template. The materials exhibited well-ordered mesostructures and were characterized by X-ray diffraction, nitrogen sorption, TEM, TGA, FTIR, and solid-state NMR measurements. The materials thus obtained were employed as adsorbents to remove different types of dyes, for example, cationic dyes methylene blue and phenosafranine, anionic orange II, and amphoteric rhodamine B, from aqueous solutions. The materials exhibited a remarkably high adsorption capacity than activated carbon due to their ordered mesostructures, a large number of phosphonic acid groups, and high surface areas. The adsorption was mainly governed by electrostatic interaction, but also involved π–π stacking interaction as well as hydrogen bonding. The adsorption kinetics can be better fitted by the pseudo-second order model. The adsorption process was controlled by the mechanisms of external mass transfer and intraparticle diffusion. The materials retained more than 97% dye removal efficiency after use for five consecutive cycles.
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Effect of carboxylic acid of Periodic Mesoporous Organosilicas on the fructose-to-5-hydroxymethylfurfural conversion in dimethylsulfoxide systems
2014Co-Authors: Saikat Dutta, Hsienming KaoAbstract:This manuscript presents the preparation and catalytic application of highly ordered benzene bridged Periodic Mesoporous Organosilicas (PMOs) functionalized with carboxylic acid (–COOH) group at varied density. The COOH-functionalized PMOs were synthesized by one-step condensation of 1,4-bis (triethoxysilyl) benzene and carboxylic group containing organosilane carboxyethylsilanetriol sodium salt using Brij-76 as the template. The obtained materials were characterized by a mean of methods including powder X-ray diffraction, nitrogen adsorption-desorption, scanning- and transmission electron microscopy, and 13C solid-state nuclear magnetic resonance measurements. The potentials of the obtained PMO materials with ordered mesopores were examined as solid catalysts for the chemical conversion of fructose to 5-hydroxymethylfurfural (HMF) in an organic solvent. The results showed that COOH-functionalized PMO with 10% COOH loading exhibited best results for the fructose to HMF conversion and selectivity. The high surface area, the adequate density acid functional group, and the strength of the PMO materials contributing to a promising catalytic ability were observed
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synthesis bifunctionalization and remarkable adsorption performance of benzene bridged Periodic Mesoporous Organosilicas functionalized with high loadings of carboxylic acids
2013Co-Authors: Fakuen Shieh, Hsienming Kao, Yiwen Chen, Juti Rani Deka, Shihhsiang LiaoAbstract:Highly ordered benzene-bridged Periodic Mesoporous Organosilicas (PMOs) that were functionalized with exceptionally high loadings of carboxylic acid groups (COOH), up to 80 mol % based on silica, have been synthesized and their use as adsorbents for the adsorption of methylene blue (MB), a basic dye pollutant, and for the loading and release of doxorubicin (DOX), an anticancer drug, is demonstrated. These COOH-functionalized benzene-silicas were synthesized by the co-condensation of 1,4-bis(triethoxysilyl) benzene (BTEB) and carboxyethylsilanetriol sodium salt (CES), an organosilane that contained a carboxylic acid group, in the presence of non-ionic oligomeric surfactant Brij 76 in acidic medium. The materials thus obtained were characterized by a variety of techniques, including powder X-ray diffraction (XRD), nitrogen-adsorption/desorption isotherms, TEM, and (13)C and (29)Si solid-state NMR spectroscopy. Owing to the exceptionally high loadings of COOH groups, their high surface areas, and possible π-π-stacking interactions, these adsorbents have very high adsorption capacities and extremely rapid adsorption rates for MB removal and for the controlled loading/release of DOX, thus manifesting their great potential for environmental and biomedical applications.
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highly carboxylic acid functionalized ethane bridged Periodic Mesoporous Organosilicas synthesis characterization and adsorption properties
2012Co-Authors: Hsienming Kao, Shihhsiang Liao, Chihhsuan Chung, Diganta Saikia, Peiying Chao, Yuhan ChenAbstract:Functionalization of Periodic Mesoporous Organosilicas (PMOs) with high loadings of pendant organic groups to form bifunctional PMOs with ordered mesostructures remains a challenging objective. Herein, we report that well-ordered ethane-bridged PMOs functionalized with exceptionally high loadings of pendant carboxylic acid groups (up to 80 mol % based on silica) were synthesized by the co-condensation of 1,4-bis(trimethoxysilyl)ethane (BTME) and carboxyethylsilanetriol sodium salt (CES) with Pluronic P123 as the template and KCl as an additive under acidic conditions. The bifunctional materials were characterized by using a variety of techniques, including powder X-ray diffraction, nitrogen-adsorption/desorption, TEM, and solid-state (13)C and (29)Si NMR spectroscopy. Zeta-potential measurements showed that the surface negative charges increased with increasing the CES content. This property makes them potential candidates for applications in drug adsorption. The excellent adsorption capacity of these bifunctional PMOs towards an anticancer drug (doxorubicin) was also demonstrated.
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synthesis and characterization of cubic thiol functionalized Periodic Mesoporous Organosilicas as effective mercury ion adsorbents
2009Co-Authors: Chiahsiu Liao, Yuchi Pan, Chaolin Yeh, Hsienming KaoAbstract:Abstract Well-ordered thiol-functionalized Periodic Mesoporous Organosilicas (SH-PMO) with ethane bridging groups and cubic Pm3n symmetry for aqueous mercury removal have been synthesized via co-condensation of tetramethoxysilane (TMOS) with 1,2-bis(trimethoxysilyl)ethane (BTME) and 3-mercaptopropyltrimethoxysilane (MPTMS) in a highly acidic medium by using cetyltriethylammonium bromide (CTEABr) as the template. The SH-PMO materials thus obtained have been characterized by X-ray diffraction, nitrogen physical sorption, thermogravimetric analysis, and solid-state 29Si and 13C NMR spectroscopy. We have found that it is necessary to employ a controlled amount of BTME in order to preserve the cubic Mesoporous structure in the resulting material when a high quantity of mercaptopropyl groups is incorporated. Direct evidence of the presence of chemically attached thiol and ethane moieties is provided by 29Si and 13C magic angle spinning (MAS) NMR spectroscopy. The maximum content of the attached thiol group (–SH) in the Mesoporous framework is 2.40 mmol/g. The total access of the Hg2+ ions to every complexation site, i.e., an Hg/S ratio close to 1, in the SH-PMO materials is also demonstrated, and a maximum mercury loading capacity of 464 mg/g is achieved. This makes its effectiveness for mercury ion trapping comparable to that of the highest capacity materials previously reported. 13C cross-polarization magic angle spinning (CPMAS) NMR demonstrates that the 13C chemical shift of the carbon atom adjacent to the –SH group is highly sensitive to the Hg2+ ion binding.
Qihua Yang - One of the best experts on this subject based on the ideXlab platform.
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functionalized Periodic Mesoporous Organosilicas for catalysis
2009Co-Authors: Qihua Yang, Jian Liu, Lei ZhangAbstract:Periodic Mesoporous Organosilicas (PMOs), one of most advanced organic–inorganic hybrid materials, have attracted much research attention because of their combined advantages of ordered Mesoporous structure and fusion of organic and inorganic fragments within the pore wall. PMOs with diverse mesostructures, morphologies and compositions have emerged in the past few years, and shown unprecedented properties. Recent years have seen the great progress in the controlled synthesis of functionalized PMOs towards specific application demands, particularly in catalysis. This Feature Article describes selected examples of the synthesis of functionalized PMOs for catalytic applications in the past few years.
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phosphonic acid functionalized Periodic Mesoporous Organosilicas and their potential applications in selective enrichment of phosphopeptides
2009Co-Authors: Peiyuan Wang, Jie Yang, Liang Zhao, Hua Zhong, Hanfa Zou, Qihua YangAbstract:Phosphonic acid functionalized Periodic Mesoporous Organosilicas were synthesized by co-condensation of 1,2-bis(trimethoxysilyl)ethane and diethoxyphosphorylethyl-triethoxysilane in acidic medium using Brij-76 as a template. Structural characterizations showed that the Mesoporous materials with 2-D hexagonal mesostructures could be obtained in the presence of an inorganic salt, NaCl. The results of transmission electron microscopy revealed that the materials synthesized with NaCl/Brij-76 mass ratios of 3 and 4 had extensive structural defect holes in the nanochannels. After coordinating metal ions (Zr4+ and Fe3+) with phosphonic acid in the mesopore, the materials were applied as the potential immobilized metal affinity chromatographic adsorbent for the selective enrichment of phosphopeptides. Because of the stronger affinity interaction between the coordinated metal ions and the phosphoryl groups of phosphopeptides, the higher surface area, and the unique Mesoporous structure, the capture of the phosphop...
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Periodic Mesoporous Organosilicas with 1 4 diethylenebenzene in the Mesoporous wall synthesis characterization and bioadsorption properties
2007Co-Authors: Jian Liu, Xin Shi, Jie Yang, Qihua YangAbstract:The 1,4-diethylenebenzene-bridged Mesoporous Organosilicas and bifunctional Periodic Mesoporous Organosilicas with various amounts of 1,4-diethylenebenzene and ethane bridging groups in the mesopor...
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synthesis characterization and catalytic activity of sulfonic acid functionalized Periodic Mesoporous Organosilicas
2004Co-Authors: Qihua Yang, Jian Liu, Jie Yang, Mahendra P Kapoor, Shinji InagakiAbstract:Abstract Sulfonic acid-functionalized Periodic Mesoporous Organosilicas were synthesized directly by cocondensation of (R′O) 3 Si R Si(OR′) 3 (R = CH 2 CH 2 and C 6 H 4 ; R′ = CH 3 and C 2 H 5 ) with 3-mercaptopropyltrimethoxysilane (MeO) 3 SiCH 2 CH 2 CH 2 SH in the presence of H 2 O 2 using nonionic oligomeric polymer surfactant C 18 H 37 (OCH 2 CH 2 ) 10 OH in acidic medium. The sulfonic acid functionalities ( SO 3 H) were generated in situ by oxidation of the propylthiol using H 2 O 2 as oxidant during the synthesis process. Powder X-ray diffraction patterns and nitrogen sorption indicate the formation of well-ordered Mesoporous material with uniform porosity. The highest acid-exchange capacity (acid–base titration methods) was 1.72 H + mmol/g. Complete oxidation of SH to SO 3 H was observed as evidenced by X-ray photoelectron spectroscopy. For comparison, the sulfonic acid-functionalized Mesoporous Organosilicas were also prepared by a grafting method. The catalytic properties of the materials were investigated in liquid-phase condensation of phenol with acetone to form Bisphenol A. All sulfonic acid-functionalized Mesoporous Organosilicas show high catalytic activity. The highest TOF obtained for the Mesoporous organosilica is 17.2.
Shinji Inagaki - One of the best experts on this subject based on the ideXlab platform.
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lanthanide grafted bipyridine Periodic Mesoporous Organosilicas bpy pmos for physiological range and wide temperature range luminescence thermometry
2020Co-Authors: Anna M Kaczmarek, Shinji Inagaki, Yoshifumi Maegawa, Anatolii Abalymov, Andre G Skirtach, Pascal Van Der VoortAbstract:2,2'-Bipyridine is the most widely used chelating ligand for developing metal complexes in coordination and supramolecular chemistry. Here, we present a series of three bipyridine Periodic Mesoporous Organosilicas (BPy-PMOs) grafted with lanthanide β-diketonate complex for the purpose of obtaining thermochromic materials, which can be employed as ratiometric temperature sensors. Such thermometers are based on the ratio of two emission intensity peaks and are not affected by factors such as alignment or optoelectronic drift of the excitation source and detectors. Three thermometric systems are studied: Dy-Dy, Tb-Sm, and Tb-Eu with the first two showing very attractive performance. For the first two systems, some of the best reported to date relative sensitivities are observed. In the BPy-PMO@Dy(acac)3 system, it is very unusual that the 4I15/2→ 6H15/2 transition is already occupied at low temperature such as 200 K, which influences its thermometric behavior. The Tb-Sm shows excellent performance in the physiological range and when suspended in water. We have additionally confirmed that the BPy-PMO hybrid materials lack toxicity to human cells, proving them very promising candidates for biomedical thermometric applications.
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a versatile solid photosensitizer Periodic Mesoporous Organosilicas with ruthenium tris bipyridine complexes embedded in the pore walls
2016Co-Authors: Hiroyuki Takeda, Takao Tani, Yasutomo Goto, Masataka Ohashi, Tetsu Ohsuna, Shinji InagakiAbstract:Here, the synthesis of Periodic Mesoporous Organosilicas (PMOs) containing large amounts of ruthenium(II) (Ru) tris(bipyridine) complexes within the pore walls as a solid photosensitizer is reported. The PMOs containing Ru complexes (Ru-PMOs) are synthesized from highly purified Ru complex precursors with three attached alkylsilatrane groups in the presence of a nonionic surfactant (triblock copolymer) using polyacrylic acid as a promoter. The Ru-PMOs show strong absorption in the visible light region up to 600 nm due to a metal–ligand charge transfer band, and redox behaviour at ≈0.8 V versus Ag/AgNO3 due to one-electron oxidation, that are very similar to those of homogeneous Ru(dmb)3(PF6)2 (dmb = 4,4′-dimethyl-2,2′-bipyridine) solution, despite the fact that the Ru complexes are embedded in the pore walls at high density. Ru-PMOs loaded with platinum metal or iridium oxide provide efficient photocatalysis for hydrogen evolution or water oxidation, respectively, under irradiation with visible light up to 600 nm in the presence of sacrificial agents. These results indicate that Ru-PMO is a versatile solid photosensitizer for the construction of various heterogeneous photocatalytic systems simply by placing catalytic materials in the stable mesochannels.
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formation of hexagonal and cubic fluorescent Periodic Mesoporous Organosilicas in the channels of anodic alumina membranes
2014Co-Authors: Andreas Keilbach, Shinji Inagaki, Norihiro Mizoshita, Thomas BeinAbstract:The synthesis of Periodic Mesoporous Organosilicas (PMOs) in the confinement of porous anodic alumina membranes (AAMs) was successfully achieved through a modified evaporation-induced self-assembly (EISA) process. 1,3,5-Tris(4-triethoxysilylstyryl)benzene, (a three-armed oligo(phenylenevinylene) organosilane compound, abbr. 3a-OPV), the precursor of the first reported charge-conducting PMO, was used as an organosilica source. Triblock-copolymers Pluronic F127 (EO106 PO70 EO106) or F108 (EO132 PO50 EO132) were used as structure directing agents. The block-copolymer F127 led to a 2D-hexagonal circular mesostructure within the AAM channels and the block copolymer Pluronic F108 resulted in a mesophase with a body-centered cubic (Imm) structure. Compared to the previously reported 3a-OPV-PMO film, the resulting hierarchical PMO/AAM systems have improved features, that is, the synthesized PMOs have a pore size of around 10 nm and the compounds are found to be stable against thermal treatment at temperatures of up to 200 °C and they are also stable in the electron beam of the electron microscope. Additionally, both of the resulting hierarchical Mesoporous composites show fluorescence in the visible region due to the strongly interacting phenylenevinylene chromophores in the PMO frameworks.
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syntheses properties and applications of Periodic Mesoporous Organosilicas prepared from bridged organosilane precursors
2011Co-Authors: Norihiro Mizoshita, Takao Tani, Shinji InagakiAbstract:Periodic Mesoporous Organosilicas (PMOs) prepared by surfactant-directed polycondensation of bridged organosilane precursors are promising for a variety of next-generation functional materials, because their large surface areas, well-defined nanoporous structures and the structural diversity of organosilica frameworks are advantageous for functionalization. This critical review highlights the unique structural features of PMOs and their expanding potential applications. Since the early reports of PMOs in 1999, various synthetic approaches, including the selection of hydrolytic reaction conditions, development of new precursor compounds, design of templates and the use of co-condensation or grafting techniques, have enabled the hierarchical structural control of PMOs from molecular- and meso-scale structures to macroscopic morphology. The introduction of functional organic units, such as highly fluorescent π-conjugates and electroactive species, into the PMO framework has opened a new path for the development of fluorescent systems, sensors, charge-transporting materials and solid-state catalysts. Moreover, a combinational materials design approach to the organosilica frameworks, pore wall surfaces and internal parts of mesopores has led to novel luminescent and photocatalytic systems. Their advanced functions have been realized by energy and electron transfer from framework organics to guest molecules or catalytic centers. PMOs, in which the precise design of hierarchical structures and construction of multi-component systems are practicable, have a significant future in a new field of functional materials (93 references).
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Luminescent Periodic Mesoporous Organosilicas
2009Co-Authors: Takao Tani, Norihiro Mizoshita, Shinji InagakiAbstract:Progress in the development of Periodic Mesoporous Organosilicas (PMOs) bearing luminescent organic groups is reviewed and directions for future research are highlighted. The inclusion of luminescent organic groups in the PMO framework allows for the preparation of materials with dissimilar luminescent groups in two spatially separated regions; the framework and the mesopore channels. Mesoporous silicas, in contrast, only bear luminescent dyes in the channels of the material structure. In multi-dye systems, the transfer of excitation energy from the framework donors to acceptors in the mesochannels is observed. Certain PMOs, such as biphenyl PMO, exhibit efficient light absorption due to the dense packing of chromophores in the framework, and high luminescence quantum yields, demonstrating the potential of luminescent PMOs as a lighting technology. Fluorescence studies have revealed that the interaction among bridging organic groups in PMOs differs between crystal-like and amorphous frameworks. These recent developments highlight the potential of luminescent PMOs as a new technology, which should be supported by further investigation of the optical properties and functionalization of PMOs.