Dirk De Vos - Academia.edu (original) (raw)

Papers by Dirk De Vos

Advanced Synthesis & Catalysis, 2010

The zeolite H-Beta catalyzes the retro-Diels-Alder reaction of a range of cyclopentadiene cyclo-a... more The zeolite H-Beta catalyzes the retro-Diels-Alder reaction of a range of cyclopentadiene cyclo-adducts at moderate temperatures and ambient pressure, in the presence of an active dienophile. The active catalyst was identified and optimum reaction conditions established after screening a range of zeolites in the retro-Diels-Alder reaction of the cyclopentadiene adduct of cyclopentenone. Our results suggest that retro-Diels-Alder reactions of tricyclodecadienones are catalyzed by Brønsted acids and the high catalytic performance of H-Beta catalysts can be ascribed to the optimal balance between the number of acid sites and their strength as well as to the accessibility of these sites. The methodology was then applied to a series of alkyl derivatives of cyclopentadienylcyclopentenones to provide a viable alternative synthetic route to 4-alkylcyclopentenones and the versatility of the approach was demonstrated by the successful cycloreversion of N-cyclohexyl-2azanorborn-5-ene.

Physical Chemistry Chemical Physics, 2010

Second-harmonic generation microscopy (SHGM) has been employed to study crystals of zeolite-like ... more Second-harmonic generation microscopy (SHGM) has been employed to study crystals of zeolite-like material SAPO-5 filled with p-nitroaniline (PNA). The SHG and 2-photon fluorescence response of PNA in the one-dimensional channels readily reveals the pore accessibility; intergrown crystallites containing hexagonal pyramidal components and internal diffusion barriers are found next to seemingly perfect crystals. The sensitivity of second-harmonic generation to molecular orientation allowed for mapping of the domains of differently organized PNA. Dense domains of highly aligned PNA alternate with dilute zones with loosely aligned PNA.

Journal of the American Chemical Society, 2012

The metal−organic framework NH 2 -MIL-53(Al) is the first solid-state material displaying nonline... more The metal−organic framework NH 2 -MIL-53(Al) is the first solid-state material displaying nonlinear optical switching due to a conformational change upon breathing. A switching contrast of at least 38 was observed. This transition originates in the restrained linker mobility in the very narrow pore configuration.

Organic & Biomolecular Chemistry, 2007

Peroxophosphotungstate Complex. -The catalysts afford hydroxy ether products with high trans-sele... more Peroxophosphotungstate Complex. -The catalysts afford hydroxy ether products with high trans-selectivity. Various alcohols including those with a long chain or fatty acids can be used in the reaction. -(LEVECQUE, P.; GAMMON, D.; KINFE, H. H.; JACOBS, P.; DE VOS, D.; SELS*, B.; Org.

Advanced Synthesis & Catalysis, 2008

The Journal of Organic Chemistry, 1999

KULeuven. ...

Tetrahedron Letters, 2004

Protected glycals are converted in high yields and selectivities in less than 2 h at low temperat... more Protected glycals are converted in high yields and selectivities in less than 2 h at low temperatures to 2-deoxy-2-iodoglycosyl acetates using the simple, inexpensive reagent mixture of ammonium iodide, hydrogen peroxide and acetic anhydride/acetic acid in acetonitrile. The corresponding 2-deoxy-2-bromoglycosyl acetates are obtained using ammonium bromide instead of the iodide, although longer reaction times are required and selectivities are inferior.

Angewandte Chemie International Edition, 2008

Aziridines are useful intermediates and pharmaceuticals. Therefore there is a growing need for th... more Aziridines are useful intermediates and pharmaceuticals. Therefore there is a growing need for their environmentally benign production. [1] Many olefin aziridinations rely on the addition of nitrenes, which are generated by either thermal or photochemical azide decomposition or are formed in situ from tosylimino phenyliodinane, sulfonyl azides, or chloramine-T using metal catalysts. [2] Halogens have also been proposed as catalysts in combination with chloramine-T, which is both a strong nucleophile and an oxidant. [3] In this route, pioneered by Sharpless [3a] and Komatsu, [3b] reaction of the oxidized halogen ("Br + ", "I + ") with the double bond is followed by nucleophilic attack of chloramine-T and cyclization. The main drawback of all previous reactions is the use of complex nitrogen-containing sources, which lead to N-substituted aziridines that require a subsequent deprotection step. Direct routes from olefins to unprotected aziridines have only been described for a,b-unsaturated carbonyl compounds and often require complex NH donors. Ammonia, which is the most obvious nucleophilic nitrogen source, has barely been considered in aziridinations. Only the Gabriel-Cromwell aziridination uses NH 3 , but the scope of this reaction is restricted to a,b-unsaturated a-halocarbonyl compounds. [5a,b] The direct incorporation of ammonia into olefins is therefore justly recognized as a top priority for catalysis. [6] Herein we describe the first successful catalytic synthesis of unprotected aziridines from NH 3 and simple olefins. Our method resembles a halide-assisted epoxidation, in which the olefin is attacked by "Br + " cation, which is formed in situ by oxidation of bromide, and then by water as the oxygen source. The resulting bromohydrin is then cyclized to the epoxide. As will be shown, a similar concept can be applied for the N-functionalization of styrenes by replacing water with ammonia as the nucleophile: unprotected aziridines are formed in a one-pot, micellar system using iodide as a catalyst, aqueous bleach as an oxidant, and ammonia as the nitrogen source [Eq. (1)].

Journal of Carbohydrate Chemistry, 2007

A New Procedure for Highly Regio-and Stereoselective Iodoacetoxylation of Protected Glycals and α... more A New Procedure for Highly Regio-and Stereoselective Iodoacetoxylation of Protected Glycals and α-1,2-Cyclopropanated Sugars. -Simple olefins such as styrene and indene are also converted to their corresponding 1,2-iodoacetates using the simple, inexpensive reagent mixture of NH4I, H2O2 and Ac2O. -(GAMMON*, D. W.; KINFE, H. H.; DE VOS, D. E.; JACOBS, P. A.; SELS, B. F.; J. Carbohydr. Chem. 26 (2007) 1-3, 141-157; Dep. Chem., Univ. Cape Town, Rondebosch, Cape Town 7701, S. Afr.; Eng.) -R. Staver 44-182

Advanced Synthesis & Catalysis, 2003

An overview of heterogeneous epoxidation catalysts is given, with an emphasis on practical parame... more An overview of heterogeneous epoxidation catalysts is given, with an emphasis on practical parameters such as catalyst productivity, turnover numbers and stereoselectivity. Special focus is directed towards catalysts that have resulted from research in the authors× group.

Angewandte Chemie International Edition, 2008

Clusters of silver atoms and ions have attracted the interest of scientists because of their pron... more Clusters of silver atoms and ions have attracted the interest of scientists because of their pronounced catalytic [1] and emissive properties. To prevent aggregation of the clusters into larger particles, stabilization in gas matrices at cryogenic temperatures, or in scaffolds such as polyphosphates, DNA, peptides or polymers at ambient temperature, has been suggested.

Journal of the American Chemical Society, 2010

For the first time, second-harmonic generation microscopy (SHGM) has been employed to study zeoli... more For the first time, second-harmonic generation microscopy (SHGM) has been employed to study zeolites. Large ZSM-5 crystals filled with p-nitroaniline (PNA) dipoles have been visualized. It is shown that SHGM can discriminate between the straight b-pores and the sinusoidal a-pores of this zeolite, thus revealing the intergrown structure of these crystals. Moreover, it is shown that dipole chains are formed not only in the b-pores but also in the a-pores. PNA only assembles into dipole chains of parallel orientation in those pores that are directly accessible from the outer surface. The area in which this PNA ordering prevails is limited to a strip near the outer surface of the zeolite crystal. A rationalization for these two observations is offered.

Nature Chemistry, 2011

Metal-organic frameworks (MOFs) are a class of crystalline materials that consist of metal ions a... more Metal-organic frameworks (MOFs) are a class of crystalline materials that consist of metal ions and organic ligands linked together by coordination bonds. Because of their porosity and the possibility of combining large surface areas with pore characteristics that can be tailored, these solids show great promise for a wide range of applications. Although most applications currently under investigation are based on powdered solids, developing synthetic methods to prepare defectfree MOF layers will also enable applications based on selective permeation. Here, we demonstrate how the intrinsically hybrid nature of MOFs enables the self-completing growth of thin MOF layers. Moreover, these layers can be shaped as hollow capsules that demonstrate selective permeability directly related to the micropore size of the MOF crystallites forming the capsule wall. Such capsules effectively entrap guest species, and, in the future, could be applied in the development of selective microreactors containing molecular catalysts.

Journal of the American Chemical Society, 2007

A heterogeneous catalyst containing MoO42- exchanged on layered double hydroxides (Mo-LDHs) is us... more A heterogeneous catalyst containing MoO42- exchanged on layered double hydroxides (Mo-LDHs) is used to produce 1O2 from H2O2, and with this dark 1O2, unsaturated hydrocarbons are oxidized in allylic peroxides. The oxidation kinetics are studied in detail and are compared with the kinetics of oxidation by 1O2, formed from H2O2 by a homogeneous catalyst. A model is proposed for the heterogeneously catalyzed 1O2 generation and peroxide formation. The model divides the reaction suspension in two compartments: (1) the intralamellar and intragranular zones of the LDH catalyst; (2) the bulk solution. The 2-compartment model correctly predicts the oxidant efficiency and peroxide yield for a series of olefin peroxidation reactions. 1O2 is generated at a high rate by the heterogeneous catalyst, but somewhat more 1O2 is lost by quenching with the heterogeneous catalyst than using the homogeneous catalyst. Quenching occurs mainly as a result of collision with the LDH hydroxyl surface, as is evidenced by using LDH supports containing strong 1O2 deactivators such as Ni2+. A total of 15 organic substrates were peroxidized on a preparative scale using the best Mo-LDH catalyst under optimal conditions.

ChemInform, 2002

... Manganese-substituted HTs have been used as catalysts for the oxidation of toluene, with t-Bu... more ... Manganese-substituted HTs have been used as catalysts for the oxidation of toluene, with t-BuOOH as the oxidant [45]45. Velu, S., Shah, N., Jyothi, TM and Sivasanker, S. 1999. Micropor. ...Jyothi, TM, Raja, T., Sreekumar, K., Talawar, MB and Rao, BS 2000. J. Mol. Catal. ...

ChemInform, 2002

organic chemistry, review organic chemistry, review Z 0200 22 -259 Peroxide Reactions with Anion-... more organic chemistry, review organic chemistry, review Z 0200 22 -259 Peroxide Reactions with Anion-Exchanged Layered Double Hydroxide Catalysts -[about 60 refs.]. -(DE VOS, DIRK E.; WAHLEN, JOOS; SELS, BERT F.; JACOBS, PIERRE A.; Synlett (2002) 3, 367-380; Cent. Surf. Chem. Catal., Kathol. Univ. Leuven, B-3001 Leuven, Belg.; EN)

Tetrahedron Letters, 1996

WO42--exchanged LDH catalyses the epoxidation of simple olefins and allylic alcohols. Substrate r... more WO42--exchanged LDH catalyses the epoxidation of simple olefins and allylic alcohols. Substrate reactivity, chemo-and regioselectivity vary markedly with the polarity of the peroxotungstate environment.

Physical Chemistry Chemical Physics, 2009

Nanocrystalline tungstate-exchanged layered double hydroxides of the takovite type, [Ni(x)Al(1-x)... more Nanocrystalline tungstate-exchanged layered double hydroxides of the takovite type, [Ni(x)Al(1-x)(OH)(2)](NO(3))(0.9-x)(WO(4))(0.05).mH(2)O, have been prepared with changing values of x. The morphology-texture parameters of the synthesized materials were characterized by using scanning electron microscopy and nitrogen adsorption techniques. X-Ray diffraction, diffuse reflectance spectroscopy, (27)Al MAS NMR and infrared spectroscopy were applied to study the structure and the phase purity of the tungstate exchanged materials. Identification of the tungsten state was attempted by infrared and Raman spectroscopy. The catalytic properties of the pure tungstate exchanged takovites were tested in the bromide-assisted epoxidation of terpenic olefins using H(2)O(2) as environmental benign oxidant. The bromide-assisted oxidation shows very interesting chemo-selectivity for various substrates with unique regio- and stereo-selectivity often opposite to that of many traditional methods. The activity of the tungstate catalyst was observed to highly depend on the Al content in the takovite support, most likely due to efficient charge shielding at the catalyst's surface. Tungstate exchanged on Al-rich takovite has a remarkable oxidation activity in terms of turnover frequency. Moreover, the takovite catalyst was found to be stable under reaction conditions and recyclable.

Advanced Synthesis & Catalysis, 2010

The zeolite H-Beta catalyzes the retro-Diels-Alder reaction of a range of cyclopentadiene cyclo-a... more The zeolite H-Beta catalyzes the retro-Diels-Alder reaction of a range of cyclopentadiene cyclo-adducts at moderate temperatures and ambient pressure, in the presence of an active dienophile. The active catalyst was identified and optimum reaction conditions established after screening a range of zeolites in the retro-Diels-Alder reaction of the cyclopentadiene adduct of cyclopentenone. Our results suggest that retro-Diels-Alder reactions of tricyclodecadienones are catalyzed by Brønsted acids and the high catalytic performance of H-Beta catalysts can be ascribed to the optimal balance between the number of acid sites and their strength as well as to the accessibility of these sites. The methodology was then applied to a series of alkyl derivatives of cyclopentadienylcyclopentenones to provide a viable alternative synthetic route to 4-alkylcyclopentenones and the versatility of the approach was demonstrated by the successful cycloreversion of N-cyclohexyl-2azanorborn-5-ene.

Physical Chemistry Chemical Physics, 2010

Second-harmonic generation microscopy (SHGM) has been employed to study crystals of zeolite-like ... more Second-harmonic generation microscopy (SHGM) has been employed to study crystals of zeolite-like material SAPO-5 filled with p-nitroaniline (PNA). The SHG and 2-photon fluorescence response of PNA in the one-dimensional channels readily reveals the pore accessibility; intergrown crystallites containing hexagonal pyramidal components and internal diffusion barriers are found next to seemingly perfect crystals. The sensitivity of second-harmonic generation to molecular orientation allowed for mapping of the domains of differently organized PNA. Dense domains of highly aligned PNA alternate with dilute zones with loosely aligned PNA.

Journal of the American Chemical Society, 2012

The metal−organic framework NH 2 -MIL-53(Al) is the first solid-state material displaying nonline... more The metal−organic framework NH 2 -MIL-53(Al) is the first solid-state material displaying nonlinear optical switching due to a conformational change upon breathing. A switching contrast of at least 38 was observed. This transition originates in the restrained linker mobility in the very narrow pore configuration.

Organic & Biomolecular Chemistry, 2007

Peroxophosphotungstate Complex. -The catalysts afford hydroxy ether products with high trans-sele... more Peroxophosphotungstate Complex. -The catalysts afford hydroxy ether products with high trans-selectivity. Various alcohols including those with a long chain or fatty acids can be used in the reaction. -(LEVECQUE, P.; GAMMON, D.; KINFE, H. H.; JACOBS, P.; DE VOS, D.; SELS*, B.; Org.

Advanced Synthesis & Catalysis, 2008

The Journal of Organic Chemistry, 1999

KULeuven. ...

Tetrahedron Letters, 2004

Protected glycals are converted in high yields and selectivities in less than 2 h at low temperat... more Protected glycals are converted in high yields and selectivities in less than 2 h at low temperatures to 2-deoxy-2-iodoglycosyl acetates using the simple, inexpensive reagent mixture of ammonium iodide, hydrogen peroxide and acetic anhydride/acetic acid in acetonitrile. The corresponding 2-deoxy-2-bromoglycosyl acetates are obtained using ammonium bromide instead of the iodide, although longer reaction times are required and selectivities are inferior.

Angewandte Chemie International Edition, 2008

Aziridines are useful intermediates and pharmaceuticals. Therefore there is a growing need for th... more Aziridines are useful intermediates and pharmaceuticals. Therefore there is a growing need for their environmentally benign production. [1] Many olefin aziridinations rely on the addition of nitrenes, which are generated by either thermal or photochemical azide decomposition or are formed in situ from tosylimino phenyliodinane, sulfonyl azides, or chloramine-T using metal catalysts. [2] Halogens have also been proposed as catalysts in combination with chloramine-T, which is both a strong nucleophile and an oxidant. [3] In this route, pioneered by Sharpless [3a] and Komatsu, [3b] reaction of the oxidized halogen ("Br + ", "I + ") with the double bond is followed by nucleophilic attack of chloramine-T and cyclization. The main drawback of all previous reactions is the use of complex nitrogen-containing sources, which lead to N-substituted aziridines that require a subsequent deprotection step. Direct routes from olefins to unprotected aziridines have only been described for a,b-unsaturated carbonyl compounds and often require complex NH donors. Ammonia, which is the most obvious nucleophilic nitrogen source, has barely been considered in aziridinations. Only the Gabriel-Cromwell aziridination uses NH 3 , but the scope of this reaction is restricted to a,b-unsaturated a-halocarbonyl compounds. [5a,b] The direct incorporation of ammonia into olefins is therefore justly recognized as a top priority for catalysis. [6] Herein we describe the first successful catalytic synthesis of unprotected aziridines from NH 3 and simple olefins. Our method resembles a halide-assisted epoxidation, in which the olefin is attacked by "Br + " cation, which is formed in situ by oxidation of bromide, and then by water as the oxygen source. The resulting bromohydrin is then cyclized to the epoxide. As will be shown, a similar concept can be applied for the N-functionalization of styrenes by replacing water with ammonia as the nucleophile: unprotected aziridines are formed in a one-pot, micellar system using iodide as a catalyst, aqueous bleach as an oxidant, and ammonia as the nitrogen source [Eq. (1)].

Journal of Carbohydrate Chemistry, 2007

A New Procedure for Highly Regio-and Stereoselective Iodoacetoxylation of Protected Glycals and α... more A New Procedure for Highly Regio-and Stereoselective Iodoacetoxylation of Protected Glycals and α-1,2-Cyclopropanated Sugars. -Simple olefins such as styrene and indene are also converted to their corresponding 1,2-iodoacetates using the simple, inexpensive reagent mixture of NH4I, H2O2 and Ac2O. -(GAMMON*, D. W.; KINFE, H. H.; DE VOS, D. E.; JACOBS, P. A.; SELS, B. F.; J. Carbohydr. Chem. 26 (2007) 1-3, 141-157; Dep. Chem., Univ. Cape Town, Rondebosch, Cape Town 7701, S. Afr.; Eng.) -R. Staver 44-182

Advanced Synthesis & Catalysis, 2003

An overview of heterogeneous epoxidation catalysts is given, with an emphasis on practical parame... more An overview of heterogeneous epoxidation catalysts is given, with an emphasis on practical parameters such as catalyst productivity, turnover numbers and stereoselectivity. Special focus is directed towards catalysts that have resulted from research in the authors× group.

Angewandte Chemie International Edition, 2008

Clusters of silver atoms and ions have attracted the interest of scientists because of their pron... more Clusters of silver atoms and ions have attracted the interest of scientists because of their pronounced catalytic [1] and emissive properties. To prevent aggregation of the clusters into larger particles, stabilization in gas matrices at cryogenic temperatures, or in scaffolds such as polyphosphates, DNA, peptides or polymers at ambient temperature, has been suggested.

Journal of the American Chemical Society, 2010

For the first time, second-harmonic generation microscopy (SHGM) has been employed to study zeoli... more For the first time, second-harmonic generation microscopy (SHGM) has been employed to study zeolites. Large ZSM-5 crystals filled with p-nitroaniline (PNA) dipoles have been visualized. It is shown that SHGM can discriminate between the straight b-pores and the sinusoidal a-pores of this zeolite, thus revealing the intergrown structure of these crystals. Moreover, it is shown that dipole chains are formed not only in the b-pores but also in the a-pores. PNA only assembles into dipole chains of parallel orientation in those pores that are directly accessible from the outer surface. The area in which this PNA ordering prevails is limited to a strip near the outer surface of the zeolite crystal. A rationalization for these two observations is offered.

Nature Chemistry, 2011

Metal-organic frameworks (MOFs) are a class of crystalline materials that consist of metal ions a... more Metal-organic frameworks (MOFs) are a class of crystalline materials that consist of metal ions and organic ligands linked together by coordination bonds. Because of their porosity and the possibility of combining large surface areas with pore characteristics that can be tailored, these solids show great promise for a wide range of applications. Although most applications currently under investigation are based on powdered solids, developing synthetic methods to prepare defectfree MOF layers will also enable applications based on selective permeation. Here, we demonstrate how the intrinsically hybrid nature of MOFs enables the self-completing growth of thin MOF layers. Moreover, these layers can be shaped as hollow capsules that demonstrate selective permeability directly related to the micropore size of the MOF crystallites forming the capsule wall. Such capsules effectively entrap guest species, and, in the future, could be applied in the development of selective microreactors containing molecular catalysts.

Journal of the American Chemical Society, 2007

A heterogeneous catalyst containing MoO42- exchanged on layered double hydroxides (Mo-LDHs) is us... more A heterogeneous catalyst containing MoO42- exchanged on layered double hydroxides (Mo-LDHs) is used to produce 1O2 from H2O2, and with this dark 1O2, unsaturated hydrocarbons are oxidized in allylic peroxides. The oxidation kinetics are studied in detail and are compared with the kinetics of oxidation by 1O2, formed from H2O2 by a homogeneous catalyst. A model is proposed for the heterogeneously catalyzed 1O2 generation and peroxide formation. The model divides the reaction suspension in two compartments: (1) the intralamellar and intragranular zones of the LDH catalyst; (2) the bulk solution. The 2-compartment model correctly predicts the oxidant efficiency and peroxide yield for a series of olefin peroxidation reactions. 1O2 is generated at a high rate by the heterogeneous catalyst, but somewhat more 1O2 is lost by quenching with the heterogeneous catalyst than using the homogeneous catalyst. Quenching occurs mainly as a result of collision with the LDH hydroxyl surface, as is evidenced by using LDH supports containing strong 1O2 deactivators such as Ni2+. A total of 15 organic substrates were peroxidized on a preparative scale using the best Mo-LDH catalyst under optimal conditions.

ChemInform, 2002

... Manganese-substituted HTs have been used as catalysts for the oxidation of toluene, with t-Bu... more ... Manganese-substituted HTs have been used as catalysts for the oxidation of toluene, with t-BuOOH as the oxidant [45]45. Velu, S., Shah, N., Jyothi, TM and Sivasanker, S. 1999. Micropor. ...Jyothi, TM, Raja, T., Sreekumar, K., Talawar, MB and Rao, BS 2000. J. Mol. Catal. ...

ChemInform, 2002

organic chemistry, review organic chemistry, review Z 0200 22 -259 Peroxide Reactions with Anion-... more organic chemistry, review organic chemistry, review Z 0200 22 -259 Peroxide Reactions with Anion-Exchanged Layered Double Hydroxide Catalysts -[about 60 refs.]. -(DE VOS, DIRK E.; WAHLEN, JOOS; SELS, BERT F.; JACOBS, PIERRE A.; Synlett (2002) 3, 367-380; Cent. Surf. Chem. Catal., Kathol. Univ. Leuven, B-3001 Leuven, Belg.; EN)

Tetrahedron Letters, 1996

WO42--exchanged LDH catalyses the epoxidation of simple olefins and allylic alcohols. Substrate r... more WO42--exchanged LDH catalyses the epoxidation of simple olefins and allylic alcohols. Substrate reactivity, chemo-and regioselectivity vary markedly with the polarity of the peroxotungstate environment.

Physical Chemistry Chemical Physics, 2009

Nanocrystalline tungstate-exchanged layered double hydroxides of the takovite type, [Ni(x)Al(1-x)... more Nanocrystalline tungstate-exchanged layered double hydroxides of the takovite type, [Ni(x)Al(1-x)(OH)(2)](NO(3))(0.9-x)(WO(4))(0.05).mH(2)O, have been prepared with changing values of x. The morphology-texture parameters of the synthesized materials were characterized by using scanning electron microscopy and nitrogen adsorption techniques. X-Ray diffraction, diffuse reflectance spectroscopy, (27)Al MAS NMR and infrared spectroscopy were applied to study the structure and the phase purity of the tungstate exchanged materials. Identification of the tungsten state was attempted by infrared and Raman spectroscopy. The catalytic properties of the pure tungstate exchanged takovites were tested in the bromide-assisted epoxidation of terpenic olefins using H(2)O(2) as environmental benign oxidant. The bromide-assisted oxidation shows very interesting chemo-selectivity for various substrates with unique regio- and stereo-selectivity often opposite to that of many traditional methods. The activity of the tungstate catalyst was observed to highly depend on the Al content in the takovite support, most likely due to efficient charge shielding at the catalyst's surface. Tungstate exchanged on Al-rich takovite has a remarkable oxidation activity in terms of turnover frequency. Moreover, the takovite catalyst was found to be stable under reaction conditions and recyclable.