Synthesis of a new iron(III) porphyrin acrylate-styrene copolymer and its catalysis for hydroxylation of cyclohexane

A new iron(III) porphyrin acrylate-styrene copolymer, P[(PorFe)A-S], was synthesized by the reaction of iron(III) porphyrin acrylate with styrene and characterized by UV-Vis, Infrared spectra (IR), inductively coupled plasmaatomic emission spectrometry (ICP) and molecular weight determination. Its catalytic activity in the hydroxylation of cyclohexane for model cytochrome P450 in the P[(PorFe) A-S]-O₂-ascrobate-thiosalicylic acid system has been studied. It was found that the P[(PorFe)A-S] has a higher catalytic activity than non-supported iron(III) porphyrin and its high catalytic activity remained in reuse. The catalytic activity of P[(PorFe)A-S] was discussed in the view of the microenvironment of iron(III) porphyrin. It is proposed that the catalytic activity of the P[(PorFe)A-S] may be further enhanced by construction of a homophase catalytic system containing the iron(III) porphyrin acrylate-styrene copolymer. Translated from Acta Scientiarum Naturalium Universitatis Sunyatseni, 2006, 45(1): 61–63 [译自: 中山大学学报 (自然科学版)]     

P-450 Type Activation of Dioxygen by Heterogenized Metal Porphyrins: Comparison with the Corresponding Homogeneous Systems

The protons of silanol groups on a silica or silica-alumina surface are replaced by metal(III) porphyrin cations, FeTPP⁺, MnTPP⁺, and CoTPP⁺ (TPP = tetraphenylporphyrin). The heterogenized iron(III) or manganese(III) porphyrin supported on silica thus prepared can activate dioxygen in the presence of excess amounts of NaBH₄ and cyclohexene, affording cyclohexanol and cyclohex-2-ene-1-ol in a 4:1 ratio, which is the same as the ratio observed in the known P-450 type oxidation of cyclohexene catalyzed by a homogeneous manganese porphyrin (MnTPPCl) in the presence of NaBH₄ used as an electron source. The heterogenized iron(III) porphyrin shows a reactivity comparable with that of the corresponding heterogenized manganese(III) porphyrin. On the other hand, substitution of the heterogenized iron(III) porphyrin by the corresponding homogeneous catalyst, FeTPPCl, results in drastic change in the product ratio; the ratio of cyclohexanol to cyclohex-2-ene-l-ol is reversed, suggesting that the oxidation of cyclohexene proceeds via radical chain autoxidation reactions. The catalytic activity for the P-450 type oxidation is diminished while FeTPPCl is converted to the μ-oxo-dimer (FeTPP)₂O. Cobalt(III) porphyrin in a homogeneous system also affords the autoxidation products. Such a mechanistic difference between the homogeneous and heterogeneous metal porphyrins in the oxidation of cyclohexene by dioxygen has been confirmed by kinetic studies in which the P-450 type oxidation and autoxidation obey different kinetics.     

Catalytic Oxidation of Cyclohexane and Cyclooctene over a New Metalloporphyrin Supported on VOPO4 Catalyst

In this work, we report the use of oxovanadium phosphate as support of the 5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin iron (III) chloride (Fe(TDCPP)Cl) and of the 5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin manganese (III) chloride (Mn(TDCPP)Cl) catalysts for cyclohexane and cyclooctene oxidations by iodosylbenzene. The catalytic results have shown that oxovanadium phosphate support is suitable for metalloporphyrin catalysts leading to an efficient system for the cyclooctene epoxidation and very selective for cyclohexane hydroxylation.     

The catalytic activity of immobilized on modified silica metalloporphyrins bearing antioxidative 2,6-di-tert-butylphenol pendants

A comparative study of the catalytic activity of supported manganese(III) and iron(III) chlorides of meso-tetrakis(3,5-di-tert-butyl-4-hydroxyphenyl)porphyrin (R₄PMnCl, R₄PFeCl) and meso-tetraphenylporphyrin (TPPMnCl, TPPFeCl) is reported. The metalloporphyrins have been immobilized via coordination bond on the surface of two series of imidazole modified silica, imidazole propyl silica (IPS) and imidazole 3-(glycidyloxypropyl) silica (IGOPS). The heterogenised catalysts have been evaluated for hydrocarbon oxidation by sodium periodate. The critical role of 2,6-di-tert-butylphenol groups on the periphery of porphyrin ring in their catalytic activity has been evaluated and pertinent structural and mechanistic aspects are discussed.     

不同金属卟啉光催化降解亚甲基蓝性能研究

以四苯基卟啉(TPP)为原料,通过金属插入反应,获得FeTPP、ZnTPP、CoTPP、MnTPP,并用UV-Vis对其进行了表征.将合成的金属卟啉用于光催化体系,进行亚甲基蓝溶液的光催化降解及催化剂回收实验.结果发现,以CoTPP为催化剂,在高压汞灯光照3 h后,亚甲基蓝溶液的脱色率可迭100%;不同光源的催化效果为...     

微囊型铁卟啉的制备及催化氧化环己烷研究

将四苯基铁(Ⅲ)卟啉包埋在苯乙烯和二乙烯苯的共聚物中制备微囊型催化剂。研究了苯乙烯和二乙烯苯摩尔比和搅拌速度对微囊型催化剂制备的影响,结果表明,苯乙烯和二乙烯苯摩尔比为1∶1,搅拌速度为800r/m in时,催化剂的粒子表面光滑、圆整。通过红外、扫描电镜对其进行了表征。用所制备的微囊型催化剂催化环己烷氧化,比游离的铁卟啉催化活性高,当其粒径在30~50μm时,环己醇产率为73.5%。该催化剂回收使用5次后,环己醇的产率仍可达到63.1%。     

Electroreduction of oxygen over iron macrocyclic catalysts for DMFC applications

The performance of macrocyclic catalysts in oxygen reduction was investigated for a direct methanol fuel cell. The dependence of catalytic activity on different factors was determined for two classes of precursors; namely, iron porphyrin (Fe-PC) and iron phthalocyanine (Fe-TPP). It was found that there was an optimal heat-treating temperature for each precursor. Heat-treated Fe-TPP shows maximum activity at 750 °C, while the highest performance in the case of Fe-PC is observed at 500 °C. It was shown that oxygen reduction activity is affected by the number of nitrogen bonds formed with iron, particle size, and formation of carbon layers.     

Metalloporphyrin/Iodine(III)‐Cocatalyzed Oxygenation of Aromatic Hydrocarbons

Hypervalent iodine species have a pronounced catalytic effect on the metalloporphyrin‐mediated oxygenations of aromatic hydrocarbons. In particular, the oxidation of anthracene to anthraquinone with Oxone readily occurs at room temperature in aqueous acetonitrile in the presence of 5–20 mol% of iodobenzene and 5 mol% of a water‐soluble iron(III)‐porphyrin complex. 2‐tert‐Butylanthracene and phenanthrene also can be oxygenated under similar conditions in the presence of 50 mol% of iodobenzene. The oxidation of styrene in the presence of 20 mol% of iodobenzene leads to a mixture of products of epoxidation and cleavage of the double bond. Partially hydrogenated aromatic hydrocarbons (e.g., 9,10‐dihydroanthracene, 1,2,3,4‐tetrahydronaphthalene, and 2,3‐dihydro‐1H‐indene) afford under these conditions products of oxidation at the benzylic position in moderate yields. The proposed mechanism for these catalytic oxidations includes two catalytic redox cycles: 1) initial oxidation of iodobenzene with Oxone producing the hydroxy(phenyl)iodonium ion and hydrated iodosylbenzene, and 2) the oxidation of iron(III)‐porphyrin to the oxoiron(IV)‐porphyrin cation‐radical complex by the intermediate iodine(III) species. The oxoiron(IV)‐porphyrin cation‐radical complex acts as the actual oxygenating agent toward aromatic hydrocarbons.     

含氮氧自由基和磺酸基共聚物的合成及催化性能

以2,2-偶氮二异丁腈为引发剂,苯乙烯磺酸钠（SSS）、甲基丙烯酸-2,2,6,6-四甲基哌啶醇酯（TMPM）为单体,采用自由基聚合的方法制备出无规共聚物P （TMPM-co-SSS）。然后用3-氯过氧苯甲酸将其氧化为含氮氧自由基的共聚物P （TMA-co-SSS）。最后用盐酸酸化,得到含氮氧自由基和磺酸基的双功能共聚物P （TMA-co-HSS）。在NaClO油水两相氧化体系下,研究了P （TMA-co-HSS）对苯甲醇的选择性催化氧化性能。结果表明,P （TMA-co-HSS）催化性能较好,收率最高可达89%,并且回收方便,重复使用3次活性未见明显降低。同时研究了P （TMA-co-HSS）作为固体酸催化剂在合成N-（乙氧基亚甲基）苯胺反应中的催化性能,并与对甲苯磺酸和聚苯乙烯磺酸的催化性能进行了对比。结果表明,P （TMA-co-HSS）催化性能优异,收率可以达到97%,远高于聚苯乙烯磺酸,与对甲苯磺酸相当,而且循环使用5次后,收率未见明显降低。     

Binuclear Iron(III) Phthalocyanine(μ‐Oxodimer)‐Catalyzed Oxygenation of Aromatic Hydrocarbons with Iodosylbenzene Sulfate and Iodosylbenzene as the Oxidants

Two binuclear iron(III) phthalocyanine‐(μ‐oxodimer) complexes were tested in catalytic oxygenation reactions of several aromatic hydrocarbons using iodosylbenzene (PhIO)_n or oligomeric iodosylbenzene sulfate [(PhIO)₃SO₃]_n as the oxidants. Results of this study demonstrate that [(PhIO)₃SO₃]_n is the most reactive oxygenating reagent that can be used as a safe and convenient alternative to the thermally unstable and potentially explosive iodosylbenzene. The pyridine‐containing binuclear μ‐oxobis{iron(III)‐pyridino[3,4]‐9(10),16(17),23(24)‐tri‐tert‐butyltribenzoporphyrazine} is significantly more active as compared to the traditional μ‐oxobis[iron(III)‐2,9(10),16(17),23(24)‐tetra‐tert‐butylphthalocyanine].     

Copolymerization of carbon monoxide and styrene with the Nd(III)–Cu(II) catalyst

In this article, the linear alternating copolymer of carbon monoxide and styrene was obtained using the Nd(III)–Cu(II) catalyst. It was found that the introducing order of the catalyst components can affect the catalytic activity, and the pre-prepared catalyst had higher catalytic activity than the in situ catalyst. The promoting effect of copper acetate on the catalytic activity was also investigated. The structure of the copolymer was characterized by means of IR, ¹H-NMR, ¹³C-NMR, WXRD, and EA methods. The thermal decomposition properties were checked by the way of TGA. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 8–13, 2001     

NR吸油材料的制备及性能研究

以甲基丙烯酸十八酯-丙烯酸丁酯-苯乙烯（SMA—BA-St）共聚物作吸油剂、NR接枝共聚物作相容剂制备NR吸油材料并对其性能进行研究。结果表明，SMA—BA—St共聚物与NR接枝马来酸酐（接枝率为27．07％）用量比为10／5时制得的NR吸油材料吸油性能、耐热老化性能和热稳定性能好，强度高，具有较高的实用价值。     

铁-锌卟啉框架材料及其可见光催化降解罗丹明B

以5,10,15,20-四-(4-羧基苯基)锌卟啉(ZnTCPP)为配体，以金属Fe为节点构筑了具有三维网状结构的铁-锌卟啉框架材料PCN-600(Zn)，采用PXRD、SEM、UV-vis DRS对所得材料进行了表征，并将其用于可见光下罗丹明B(RhB)的降解反应，考察了H2O2浓度对PCN-600(Zn)光催化性能的影响，并通过捕获实验确定了光催化反应过程中的主要活性物种，对比了PCN-600(Zn)与另一种锆-锌卟啉框架材料PCN-222(Zn)的光催化性能。结果表明，在H2O2的协同作用下，PCN-600(Zn)对RhB的降解表现出显著的催化活性，可见光照射90分钟后降解率可达94.2%，在实验范围内，随着H2O2浓度的增加，PCN-600(Zn)的催化活性不断提高，H2O2用量为4 mL时可最大程度上提升催化剂效率；实验证明在催化过程中，空穴（h+）为主要活性中间体，·OH 和·O2-也起到了一定的作用。此外，PCN-600(Zn)的光催化性能明显强于PCN-222(Zn)，相同实验条件下，前者罗丹明B的降解率可达95.9%，后者仅达67.6%。     

Nitric oxide synthase-like activity of ion exchange resins modified with iron (III) porphyrins in the oxidation of l-arginine by H2O2: Mechanistic insights

Resin supported iron (III) porphyrins, prepared by strong electrostatic interactions between the ionic iron (III) porphyrins and counter ionic groups on the surface of the support, were found to be very efficient catalysts for H₂O₂ mediated oxidation of l-arginine with the formation of citrulline and nitric oxide, and the yields of these products were remarkably higher than those obtained with corresponding soluble iron (III) porphyrins. No leaching of iron porphyrin or uncomplexed iron ions was observed. A high-valent iron–oxo porphyrin complex was suggested as a reactive intermediate for this oxidation reaction.     

Photokatalytische Aktivierung von molekularem Sauerstoff mittels Eisen(III)porphyrin‐Komplexen

Photochemical charge transfer excitation of tetra‐phenyl(porphyrinato)iron(III) complexes yields tetraphenyl) (porphyrinato)iron(II) which is able to coordinate molecular oxygen under formation of oxo‐[tetraphenyl(porphyrinato)]‐ iron(IV). Based on this photochemical reaction pathway photocatalytic oxygenation of α‐pinene and other alkenes can be initiated. Iron(III) complexes of tetramesitylporphyrin, tetrakis‐(pentafluorophenyl)porphyrin, octa‐β‐bromo‐tetrakis‐(pentafluorophenyl)porphyrin, and octa‐β‐chloro‐tetrakis‐(pentafluorophenyl)porphyrin were investigated photochemically with the aim to improve the low photochemical efficiency of tetraphenyl(porphyrinato)iron(III). The influence of substituents on the porphyrin ligand on the photochemical behavior of the corresponding iron(III) complexes is measured mainly by means of temperature dependent UV/Vis spectroscopy. Both, the yield of oxygenation products formed photocatalytically with α‐pinene and the product distribution (allylic alcohols versus epoxide) depend on the design of the porphyrin ligands coordinated with iron(III).     

High-valent iron(IV)-oxo complexes of heme and non-heme ligands in oxygenation reactions

High-valent iron(IV)-oxo species have been implicated as the key reactive intermediates in the catalytic cycles of dioxygen activation by heme and non-heme iron enzymes. Our understanding of the enzymatic reactions has improved greatly via investigation of spectroscopic and chemical properties of heme and non-heme iron(IV)-oxo complexes. In this Account, reactivities of synthetic iron(IV)-oxo porphyrin pi-cation radicals and mononuclear non-heme iron(IV)-oxo complexes in oxygenation reactions have been discussed as chemical models of cytochrome P450 and non-heme iron enzymes. These results demonstrate how mechanistic developments in biomimetic research can help our understanding of dioxygen activation and oxygen atom transfer reactions in nature.     

The Radical Versus Non-radical Reactive Intermediates in the Iron(III) Porphyrin Catalyzed Oxidation Reactions by Hydroperoxides, Hydrogen Peroxide and Iodosylarene

In the catalytic reaction of an iron(III) porphyrin with t-BuOOH, CumOOH, H₂O₂ and C₆F₅IO, cyclohexene was used as a probe substrate. The selective hydroxylation of cyclohexene by hydroperoxides proceeds through radical path and this has been utilized for successful dioxygen activation/autooxidation. For other oxidants epoxide was the major product and the reactions proceed through non-radical path.     

Preparation of a new precipitated iron catalyst for Fischer–Tropsch synthesis

It is well known that a typical precipitated iron catalyst was prepared by iron(III) nitrate (Fe(NO₃)₃). The modified iron catalyst was prepared by iron(II) sulfate in our laboratory. The results from catalytic performance tests showed that the iron catalyst prepared from iron sulfate (cat-S) has the higher activity for Fischer–Tropsch synthesis (FTS) than the catalyst prepared from iron nitrate (cat-N). The results from XRD of catalyst before use showed the difference definitely. The XRD patterns of these catalysts indicate that the main phase of cat-N is Fe₂O₃, whereas the phases of cat-S are a mixture of Fe₂O₃ and Fe₃O₄. It is considered that magnetite was directly formed during precipitation and contained in the catalyst before use enhances the activity for FTS.     

Catalytic decomposition of nitrous oxide over Fe-BEA zeolites: Essential components of iron active sites

The catalytic decomposition of N₂O was investigated over Fe-BEA zeolites treated with various methods such as reduction, steaming and dissolution with potassium nitrate and nitric acid solutions in order to deduce the essential components of the active sites for the decomposition. The iron species were characterized by XPS, XANES, ESR, NO adsorption, and linear sweep voltammetry. The reduction-treated Fe-BEA zeolite with the large amounts of Fe(II) and Fe(III) species showed the highest activity. On the contrary, the dissolution treatment with the potassium nitrate solution seriously deteriorated the catalytic activity of the Fe-BEA zeolite by agglomerating iron oxide clusters and interaction between iron and potassium atoms. The catalytic roles of Fe(II)/Fe(III) species and the negative effect of potassium on the catalytic activity of the Fe-BEA zeolites were discussed.     

Photodegradation of azo‐dyes in aqueous solution by polyacrylonitrile nanofiber mat‐supported metalloporphyrins

Electrospinning has been employed to fabricate uniform polyacrylonitrile and polyacrylonitrile copolymer nanofiber mats supporting metalloporphyrins (MTPP; M: Zn(II), Cu(II), Ni(II), Co(II), Fe(III) and Pd(II); TPP: meso‐tetraphenylporphyrin). The nanofiber mat‐supported metalloporphyrins are shown as efficient photocatalysts for the degradation of various azo‐dyes in aqueous solutions under visible light irradiation. The effect of transition metals on azo‐dye photodegradation has been examined. The nanofiber mat‐supported copper–porphyrin and iron–porphyrin complexes are among the most effective photocatalysts for azo‐dye degradation. Immobilization of the metalloporphyrins onto the nanofiber mats greatly facilitates the recovery and reuse of the expensive and toxic photocatalysts. Most interestingly, there are no significant degradations of the photocatalytic activities of the recycled photocatalysts. © 2012 Society of Chemical Industry