Multifunctional hollow mesoporous organic polymeric nanospheres (HMOPs) as effective heterogeneous catalysts with enhanced activity in green asymmetric organocatalysis

Xie, Guangxin; Tian, Jiekang; Wei, Shuai; Liu, Xingzuo; Ma, Xuebing

doi:10.1016/j.apcata.2018.07.043

Cited by 13 publications

(10 citation statements)

References 52 publications

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“…Exploring economical and straightforward methods for the synthesis of polystyrene-based mesoporous organic polymers is still full of challenges. − In this paper, the mesopore-abundant shells with the pore diameters of 2–15 nm in void-free HMOPBs, double-shelled HMOPBs, and HMOPSs (Figure S4) are fabricated via the Co 2+ ion-adsorbed, Co(OH) 2 porogen-generated, and porogen-removed procedure. However, the corresponding HOPBs(a) with lower surface area and pore volume (Table S1), prepared according to the similar procedure as double-shelled HMOPBs(a) in the absence of Co(OAc) 2 , is proven to be mesopore-deficient by its pore size distribution (Figure ).…”

Section: Resultsmentioning

confidence: 99%

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Hollow Mesoporous Organic Polymeric Nanobowls and Nanospheres: Shell Thickness and Mesopore-Dependent Catalytic Performance in Sulfonation, Immobilization of Organocatalyst, and Enantioselective Organocascade

Xie

Wei

Zhang

et al. 2019

Ind. Eng. Chem. Res.

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Heterogeneous asymmetric multicomponent/multicatalytic organocascade faces the enormous challenges of tedious immobilization of catalysts, mass transfer, and stereoselective control. In this paper, the mesopore-abundant and well-shaped hollow mesoporous organic polymers, nanobowls (HMOPBs) and nanospheres (HMOPSs), are fabricated via emulsion polymerization of styrene on a polystyrene (PS) core and then removal of PS, accompanied by the adsorption of Co2+ ions, transformation of Co2+ into Co(OH)2, and final removal of Co(OH)2. Among them, the nanobowl HMOPBs(a) with hollow interiors, mesoporous shells, and thin shell thickness (16 nm) possesses the largest surface area (185.7 m2 g–1) and displays the highest reaction kinetics in the sulfonation (2.85 mmol H+ g–1) and then immobilization of 9-amino(9-deoxy)epi-quinine (QNNH2, 1.35 mmol g–1). For the 2,4-substituted bulky reactants in an asymmetric double-Michael cascade, the as-fabricated functional nanobowl can provide a suitable microenvironment to meet the requirements of the good to excellent double-Michael organocascades, which originates from its thin shell thickness and mesopore-dependent shell.

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Section: Resultsmentioning

confidence: 99%

“…The preparation of poly(styrene/acrylic acid) (PS) core with a mean diameter of 142 ± 9 nm ( n = 52) is shown in the Supporting Information. 9-Amino(9-deoxy) epi -quinine (QNNH 2 ) was synthesized according to the ref . The other chemicals were of analytical grade and used as received without any further purification.…”

Section: Methodsmentioning

confidence: 99%

Hollow Mesoporous Organic Polymeric Nanobowls and Nanospheres: Shell Thickness and Mesopore-Dependent Catalytic Performance in Sulfonation, Immobilization of Organocatalyst, and Enantioselective Organocascade

Xie

Wei

Zhang

et al. 2019

Ind. Eng. Chem. Res.

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Section: Asymmetric Organocatalysismentioning

confidence: 99%

“…80 Ma and co-workers have prepared hollow mesoporous polymers (HMOPs) with 2−15 nm mesoporosity (Figure 12). 81 The mesoporous shell was post-functionalized with chlorosulfonic acid for grafting−SO 3 H groups and immobilized with 9amino(9-deoxy)epi-cinchonidine base (loading: 0.98 mmol g −1 ), to execute asymmetric aldol condensation as well as double-Michael organocascade reaction. It is intriguing that abundant mesopores (2−15 nm) in HMOPs, along with high surface area (138 m 2 g −1 ), is responsible for the materials exhibiting better catalytic effects, compared to nonporous hollow nanospheres and other heterogeneous organocatalysts, as reported by the authors.…”

Section: ■ Asymmetric Organocatalysismentioning

confidence: 99%

Cross-Linked Porous Polymers as Heterogeneous Organocatalysts for Task-Specific Applications in Biomass Transformations, CO₂ Fixation, and Asymmetric Reactions

Modak

Ghosh

Mankar

et al. 2021

ACS Sustainable Chem. Eng.

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Metal-free catalysis is particularly challenging in the context of green and sustainable chemistry. High toxicity associated with the leaching of the metals from the catalysts has notorious environmental impact. To surmount such an effect, homogeneous organocatalysis can provide a green and alternative protocol. However, it suffers the drawbacks of low activity and selectivity, because of the neighboring effect of the solvent, and it is devoid of recyclability for sustainable operations. To address such issues, solid-supported heterogeneous organocatalysts are developed, and these have been attracting increasing interest over the years. Multifunctional porous organic materials are very demanding in catalysis, because of their robustness in the structure involving strong covalent bonds between organic building blocks. Furthermore, their high specific surface area, topological diversity, and finely dispersed catalytic sites in nanoscale could make these porous organic materials as excellent scaffold for several task-specific applications. Lightweight and high inherent porosity, as well as structural stability with tenability of the active functional groups, have reinforced their tremendous potential as solid organocatalyst. In this Perspective, we highlight the latest advancements in metal-free cross-linked amorphous porous organic polymers (POPs) and crystalline covalent organic frameworks (COFs), their design principle to incorporate catalytic sites for major applications such as biomass conversion, biofuel synthesis, asymmetric organocatalysis, and CO2 fixation reactions. Several renewable and sustainable catalytic transformations could be achieved via environmentally benign pathways through this alternative metal-free approach.

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“…The mesopores were produced via the adsorption of Co 2+ during the formation of the outer shell, expansion of the compact outer shell by in situ formation of Co(OH) 2 in NaOH solution and removal of the Co(OH) 2 porogen by HCl. 37,41 The mesopores in the shell were further evidenced by the honeycomb-like convex−concave surface in a highresolution TEM image (Figure S 2d). Third, the average outer-shell thickness of 56 nm (Figure S2) and inner-shell thickness of 47 nm (Figure S1) shortened the transmission distance of reactants, which is related to R. Therefore, the hollow interior, mesoporous shell, and thin shell thickness contributed to the effective mass transfer of reactants and products in and out of the catalyst.…”

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confidence: 93%

Compartmentalization of Multiple Catalysts into Outer and Inner Shells of Hollow Mesoporous Nanospheres for Heterogeneous Multi-Catalyzed/Multi-Component Asymmetric Organocascade

Xie

Zhang

2019

ACS Catal.

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Heterogenization of multicatalyzed cascade/ tandem reactions often suffers from the detrimental interactions of incompatible catalysts. Herein, double-shelled hollow mesoporous nanospheres with isolated sites of ProTMS/-CO 2 H in the outer shell and QNNH 2 /-SO 3 H or QDNH 2 /-SO 3 H in the inner shell were fabricated as highly stereoselective catalysts in heterogeneous Michael addition/αamination organocascade reactions. The spatial compartmentalization, evidenced by TEM-EDS elemental mapping, effectively suppressed the detrimental interaction of QNNH 2 , QDNH 2 , and −SO 3 H with ProTMS/-CO 2 H in the first-step Michael addition. The hollow interior, mesoporous shell, and thin shell thickness facilitated the mass transfer of intermediates into the inner shell where α-amination occurred.

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Multifunctional hollow mesoporous organic polymeric nanospheres (HMOPs) as effective heterogeneous catalysts with enhanced activity in green asymmetric organocatalysis

Cited by 13 publications

References 52 publications

Hollow Mesoporous Organic Polymeric Nanobowls and Nanospheres: Shell Thickness and Mesopore-Dependent Catalytic Performance in Sulfonation, Immobilization of Organocatalyst, and Enantioselective Organocascade

Hollow Mesoporous Organic Polymeric Nanobowls and Nanospheres: Shell Thickness and Mesopore-Dependent Catalytic Performance in Sulfonation, Immobilization of Organocatalyst, and Enantioselective Organocascade

Cross-Linked Porous Polymers as Heterogeneous Organocatalysts for Task-Specific Applications in Biomass Transformations, CO₂ Fixation, and Asymmetric Reactions

Compartmentalization of Multiple Catalysts into Outer and Inner Shells of Hollow Mesoporous Nanospheres for Heterogeneous Multi-Catalyzed/Multi-Component Asymmetric Organocascade

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Multifunctional hollow mesoporous organic polymeric nanospheres (HMOPs) as effective heterogeneous catalysts with enhanced activity in green asymmetric organocatalysis

Cited by 13 publications

References 52 publications

Hollow Mesoporous Organic Polymeric Nanobowls and Nanospheres: Shell Thickness and Mesopore-Dependent Catalytic Performance in Sulfonation, Immobilization of Organocatalyst, and Enantioselective Organocascade

Hollow Mesoporous Organic Polymeric Nanobowls and Nanospheres: Shell Thickness and Mesopore-Dependent Catalytic Performance in Sulfonation, Immobilization of Organocatalyst, and Enantioselective Organocascade

Cross-Linked Porous Polymers as Heterogeneous Organocatalysts for Task-Specific Applications in Biomass Transformations, CO2 Fixation, and Asymmetric Reactions

Compartmentalization of Multiple Catalysts into Outer and Inner Shells of Hollow Mesoporous Nanospheres for Heterogeneous Multi-Catalyzed/Multi-Component Asymmetric Organocascade

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Cross-Linked Porous Polymers as Heterogeneous Organocatalysts for Task-Specific Applications in Biomass Transformations, CO₂ Fixation, and Asymmetric Reactions