Underevaluated Solvent Effects in Electrocatalytic CO2 Reduction by FeIII Chloride Tetrakis(pentafluorophenyl)porphyrin

Fe^III chloride tetrakis(pentafluorophenyl)porphyrin ( 1 ) is known to have poor electrocatalytic activity for the CO₂-to-CO conversion in dimethylformamide. In this work, we re-examined Fe porphyrin 1 as a CO₂ reduction catalyst in various solvents. Our results show that 1 displays fairly high electrocatalytic CO₂-to-CO activity in acetonitrile with a turnover frequency (TOF) up to 4.2×10⁴ s⁻¹. On the other hand, 1 shows a modest activity in propylene carbonate, and is inefficient to catalyze CO₂ reduction in benzonitrile, dimethylformamide, and tetrahydrofuran. Several solvent effects were considered, but none of these effects alone can explain the observed large activity difference of 1 for CO₂ reduction in these solvents. Based on the results, it is suggested that more care should be paid when comparing different CO₂ reduction catalysts because solvent effects are significant and are underevaluated.     

Inclusion Complexes of Cyclodextrins with Tetrakis(4-carboxyphenyl)porphyrin and Tetrakis(4-sulfonatophenyl)porphyrin in Aqueous Solutions

In neutral and alkaline solutions, tetrakis(4-carboxyphenyl)porphyrin (TCPP) and tetrakis(4-sulfonatophenyl)porphyrin (TSPP) form 1:1 and 2:1 host–guest inclusion complexes with -cyclodextrin (-CD), -cyclodextrin (-CD), and 6-deoxy-6-diethylamino--CD (DEA--CD), except for DEA--CD in alkaline solution. On the other hand, TCPP and TSPP form only 1:1 inclusion complexes with 6-deoxy-6-dihexylamino--CD (DHA--CD). The limited solubilities of DEA--CD in alkaline solution and DHA--CD are likely responsible for no observation of the 2:1 inclusion complex containing DEA--CD in alkaline solution and that containing DHA--CD. The equilibrium constants (Ks) of TCPP and TSPP for the formation of the inclusion complexes have been estimated from the absorption and/or fluorescence intensity changes in neutral and alkaline solutions. The K₂ values, which are the equilibrium constants for the formation of the 2:1 host–guest inclusion complex from the 1:1 inclusion complex, are about one tenth the corresponding K₁ values, except for the -CD–TSPP system in alkaline solution. In neutral solution, where DEA--CD and DHA--CD are in protonated forms, the electrostatic force operates between DEA--CD (DHA--CD) and TCPP (TSPP), leading to the greater K values than those in alkaline solution, where DEA--CD and DHA--CD exist as neutral species.     

四（五氟化苯基）卟啉氯化铁选择催化氧化超临界丙烷的反应机理

 以BHT为自由基捕捉剂，研究了四（五氟化苯基）卟啉氯化铁（Ⅲ）将超临界丙烷高选择性催化氧化为丙醇的反应机理．通过GC－MS分析发现，反应产物中有PBHT，故可认为在超临界丙烷氧化反应过程中有丙基自由基存在，初步推断反应涉及自由基机理．同时发现高浓度BHT抑制反应，低浓度BHT促进反应的现象，而以戊烷为底物时没有促进作用．这是由于BHT的位阻效应所致．并对BHT存在时超临界丙烷氧化反应机理进行了初步的推断．     

meso-四(邻烷氧基苯基)卟啉合钴的合成、表征和性能研究

合成了meso-四(邻烷氧基苯基)卟啉合钴配合物10个,其中未见文献报道的新化合物8个，研究了其合成、分离、纯化方法,首次得到了该系列化合物的晶体或固体。用¹H NMR、MS、IR、UV、元素分析等表征确证了其结构,报道和解析了该类卟啉钴配合物的¹H NMR特殊波谱现象。用差示扫描量热法(DSC)和偏光显微镜(PM)研究了该系列配合物的液晶性能,发现6个配合物具有液晶性。研究了烷氧基链长、金属离子和分子空间结构对卟啉液晶性能的影响,烷氧基链长的增加、金属配合物的形成有利于液晶性能的改善。     

Cyclohexene Promoted Efficient Biomimetic Oxidation of Alcohols to Carbonyl Compounds Catalyzed by Manganese Porphyrin under Mild Conditions

Selective oxidation of alcohols to corresponding carbonyl compounds is one of the most important processes both in academic and application research. As a kind of biomimetic catalyst, metalloporphyrins‐catalyzed aerobic oxidation of alcohols with aldehyde as hydrogen donator is gathering much attention. However, using olefins as another kind hydrogen donator for aerobic oxidation of alcohols has not been reported. In this study, a system comprising managenese porphyrin and cyclohexene for biomimetic aerobic oxidation of alcohols to carbonyl compounds was developed. The catalytic system exhibited excellent catalytic performance and selectivity towards the corresponding products for most primary and secondary alcohols under mild conditions. Based on the results obtained from experiments as well as in situ EPR (electron paramagnetic resonance) and UV‐vis spectroscopy, the role of cyclohexene was demonstrated.     

Oxidation chemistry of poly(ethylene glycol)-supported carbonylruthenium(II) and dioxoruthenium(VI) meso-tetrakis(pentafluorophenyl)porphyrin

[Ru(II)(F(20)-tpp)(CO)] (1, F(20)-tpp=meso-tetrakis(pentafluorophenyl)porphyrinato dianion) was covalently attached to poly(ethylene glycol) (PEG) through the reaction of 1 with PEG and sodium hydride in DMF. The water-soluble PEG-supported ruthenium porphyrin (PEG-1) is an efficient catalyst for 2,6-Cl(2)pyNO oxidation and PhI==NTs aziridination/amidation of hydrocarbons, and intramolecular amidation of sulfamate esters with PhI(OAc)(2). Oxidation of PEG-1 by m-CPBA in CH(2)Cl(2), dioxane, or water afforded a water-soluble PEG-supported dioxoruthenium(VI) porphyrin (PEG-2), which could react with hydrocarbons to give oxidation products in up to 80 % yield. The behavior of the two PEG-supported ruthenium porphyrin complexes in water was probed by NMR spectroscopy and dynamic light-scattering measurements. PEG-2 is remarkably stable to water. The second-order rate constants (k(2)) for the oxidation of styrene and ethylbenzene by PEG-2 in dioxane-water increase with water content, and the k(2) values at a water content of 70 % or 80 % are up to 188 times that obtained in ClCH(2)CH(2)Cl.     

MnTFPPCl模拟体系催化环己烯氧化反应性能研究

研究了高氟代金属卟啉ＭｎＴＦＰＰＣｌ催化环己烯氧化反应的催化活性,探索了反应体系中不同单氧原子给体对催化反应的影响。结果表明,ＭｎＴＦＰＰ－Ｃｌ／ＮａＯＣｌ体系有较好的催化转移氧能力。主要以ＰｈＩＯ为氧化剂,考察了轴向配体,溶剂等对ＭｎＴＦＰＰＣｌ／ＰｈＩＯ模拟体系的影响。     

Chemoselective Amination of Propargylic C(sp3)H Bonds by Cobalt(II)‐Based Metalloradical Catalysis

Highly chemoselective intramolecular amination of propargylic C(sp³)? H bonds has been demonstrated for N‐bishomopropargylic sulfamoyl azides through cobalt(II)‐based metalloradical catalysis. Supported by D_2h‐symmetric amidoporphyrin ligand 3,5‐Di^tBu‐IbuPhyrin, the cobalt(II)‐catalyzed C? H amination proceeds effectively under neutral and nonoxidative conditions without the need of any additives, and generates N₂ as the only byproduct. The metalloradical amination is suitable for both secondary and tertiary propargylic C? H substrates with an unusually high degree of functional‐group tolerance, thus providing a direct method for high‐yielding synthesis of functionalized propargylamine derivatives.     

新型-meso-四(4-十四氨基甲酰苯基)卟啉及其-金属（Co）配合物的合成与液晶性能

对羧基苯甲醛和吡咯经缩合反应制得meso-四(4-羧基苯基)卟啉(1); 1与氯化亚砜反应得meso-四(4-氯甲酰基苯基)卟啉(2); 2与n-十四胺反应制得meso-四(4-十四氨基甲酰苯基)卟啉(3); 3与CoC_l2经配位反应合成了meso-四(4-十四氨基甲酰苯基)卟啉钴(4)。 3和4为新化合物,其结构经U-Vis, ¹H NMR和IR表征。偏光显微镜和DSC检测结果表明： 3和4具有液晶性能。     

三氯化钌催化下环己烷和环己醇在离子液体中的氧化反应研究

在三氯化钌催化下,使用叔丁基过氧化氢在离子液体中可将环己烷和环己醇氧化为环己酮,结果表明环己醇的氧化具有较高的转化率和选择性．离子液体(bmim)^ PF6^-和催化剂三氯化钌均有一定的重复使用性．     

Influencing electroosmotic flow and selectivity in open tubular electrochromatography by tetrakis(pentafluorophenyl)porphyrin as capillary wall modifier

A physically adsorbed and covalently bonded porphyrin derivative, 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin, H₂TPFPP, has been used as a fused-silica capillary wall modifier in open tubular capillary electrochromatography (OT-CEC), and its influence on the electroosmotic flow (EOF) velocity and on the selectivity of OT-CEC separations of a set of model aromatic carboxylic acids has been tested. Whereas most of the coatings of this category bring about an increase in selectivity with a concomitant slow down of the EOF, H₂TPFPP coating, depending on pH of the background electrolyte used, resulted both in decreasing of EOF at pH 8.5 by 5% and in increasing of EOF by 10–43% at pH 6 and 5, respectively. The separation efficiency and the resolution of aromatic carboxylic acids separation in coated capillaries, namely in that one with covalent coating, were better than in the bare fused-silica capillary. The perspectives of H₂TPFPP as capillary wall modifier are visualized in introducing well defined electroosmotic properties of materials used for miniaturized separation channels preparation in chip-based electromigration devices.     

氧化锌负载四(4-硝基苯基)钴卟啉催化氧化环己烷性能

将四(4-硝基苯基)钴卟啉(Co-TNPP)负载在氧化锌(Zn O)载体制备负载型金属卟啉催化剂Co-TNPP/Zn O,并对其进行了紫外-可见漫反射光谱(UV-vis),红外光谱(FT-IR),X射线衍射(XRD),热重分析(TG/DTG),比表面分析(BET)和电感耦合等离子体(ICP)表征.考察了催化剂在无溶剂的条件下催化氧气氧化环己烷的性能.实验结果表明:在反应温度为150℃,氧气压力为1.2 MPa,反应时间为2.0 h的条件下,环己烷转化率9.82%,环己醇和环己酮选择性83.37%.负载型金属卟啉催化剂经过5次循环使用,环己烷的平均转化率和环己醇、环己酮平均选择性分别为9.95%、83.61%,催化剂的平均转化数为2.18×105.负载型金属卟啉催化剂Co-TNPP/Zn O在较温和的条件下表现出优良的环己烷催化氧化性能,克服了金属卟啉催化剂难以回收、无法循环使用的缺点,具有很好的工业价值和应用前景.     

Intramolecular Radical Aziridination of Allylic Sulfamoyl Azides by Cobalt(II)‐Based Metalloradical Catalysis: Effective Construction of Strained Heterobicyclic Structures

Cobalt(II)‐based metalloradical catalysis (MRC) has been successfully applied for effective construction of the highly strained 2‐sulfonyl‐1,3‐diazabicyclo[3.1.0]hexane structures in high yields through intramolecular radical aziridination of allylic sulfamoyl azides. The resulting [3.1.0] bicyclic aziridines prove to be versatile synthons for the preparation of a diverse range of 1,2‐ and 1,3‐diamine derivatives by selective ring‐opening reactions. As a demonstration of its application for target synthesis, the metalloradical intramolecular aziridination reaction has been incorporated as a key step for efficient synthesis of a potent neurokinin 1 (NK₁) antagonist in 60 % overall yield.     

Oxidation of alkanes catalyzed by manganese(III) porphyrin in an ionic liquid at room temperature

Efficient oxidation of alkanes is achieved by using an electron-deficient manganese(III) porphyrin catalyst in combination with iodobenzene diacetate in an ionic liquid at room temperature; a high-valent manganese-oxo porphyrin complex (Mn^VO) was considered as the reactive oxidation intermediate.     

活性位高度暴露的钴/氮/碳电催化剂的构建及氧还原性能研究

金属/氮/碳催化剂（M/N/C，M=Fe、Co等）是最有发展前景的非贵金属电催化剂之一，其性能依赖于催化剂表面的活性物种密度.通过常规的热解含氮前驱物与金属盐的方法制得的催化剂往往存在金属活性物种被包埋而不能有效利用的缺点.考虑到石墨相氮化碳（g-C₃N₄）富含类吡啶氮和亚纳米孔腔结构，将g-C₃N₄包覆在高导电性碳纳米笼（hCNC）表面，进而利用表层g-C₃N₄的配位和限域作用锚定大量Co²⁺离子，获得的Co/g-C₃N₄/hCNC复合物经热解后形成了活性位高度暴露、导电性好、孔结构丰富的Co/N/C催化剂.800℃热解得到的最优化催化剂在碱性介质中展现出优异氧还原活性，其起始电位（0.97 V）与商业Pt/C催化剂相当，且抗甲醇干扰性能和稳定性优异.此项研究提供了一种构建具有高度暴露活性位的M/N/C催化剂的有效策略.     

Cross-linking radical polymerization of di(meth)acrylates in the presence of cobalt(II) porphyrin

The influence of small additives of cobalt(II) porphyrin (Co^IIPn) on cross-linking radical polymerization of butane-1,4-diol dimethacrylate and its structural analog butane-1,4-diol diacrylate was studied. The kinetics of cross-linking radical polymerization of di(meth)acrylates in the absence and presence of Co^IIPn and the diffusional sorption and physical mechanical properties of the resulting polymers were studied. Cobalt(II) porphyrin decreases substantially the polymerization rate and partially suppresses the gel effect. Diacrylate polymerization in the presence of Co^IIPn proceeds with an induction period, whose value is determined by the content of Co^IIPn. Cobalt(II) porphyrin modifies the structure and properties of the formed cross-linked polymers. In the case of dimethacrylate, this is caused by the catalytic chain transfer reaction, whereas for diacrylate the reason is the reversible inhibition reaction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 807–816, May, 2006.     

Sodium Salts of Anionic Chiral Cobalt(III) Complexes as Catalysts of the Enantioselective Povarov Reaction

The sodium salts of anionic chiral cobalt(III) complexes (CCC^?Na⁺) have been found to be efficient catalysts of the asymmetric Povarov reaction of easily accessible dienophiles, such as 2,3‐dihydrofuran, ethyl vinyl ether, and an N‐protected 2,3‐dihydropyrrole, with 2‐azadienes. Ring‐fused tetrahydroquinolines with up to three contiguous stereogenic centers were thus obtained in high yields, excellent diastereoselectivities (endo/exo up to >20:1), and high enantioselectivities (up to 95:5 e.r.).     

Oxidations of alkenes catalyzed by a Mn(III) porphyrin and cationic polymer latexes

Three types of cationic polymer latexes were prepared by emulsion copolymerization of vinylbenzyl chloride, divinylbenzene and a third monomer, vinyl octadecyl ether, styrene, or n-decyl methacrylate, followed by quaternization with trimethylamine. The latexes had 44–71 nm diam and polydispersity indices of 1.06–1.10. Vinyl octadecyl ether did not copolymerize but hydrolyzed under the polymerization conditions to produce 1-octadecanol, which as a coemulsifier gave highly viscous latexes. The tetraanion 5,10,15,20-tetrakis-(2,6-dichloro-3-sulfonatophenyl) porphinatomanganese (III) chloride bound irreversibly to the cationic latexes and was an active catalyst for oxidations of alkenes by sodium hypochlorite and potassium peroxymonosulfate in the absence of added organic solvent. The porphyrin catalyst in the latexes was more active than in solution. Porphyrin catalysis gave epoxides concurrently with competing uncatalyzed hypochlorous acid oxidations to complex mixtures of allylic chlorides, allylic alcohols, α,β-unsaturated ketones, and chlorohydrins.     

Electrochemical Properties of Carbon Black AD-100 and AD-100 Promoted with Pyropolymer of Cobalt Tetra(p-methoxyphenyl)porphyrin

Carbon black AD-100: initial, activated, and promoted with pyropolymer of cobalt tetra(p-methoxyphenyl)porphyrin is characterized by a complex of electrochemical (floating electrode, rotating disk electrode, rotating ring-disk electrode, electrochemical impedance) and structural (standard porosimetry, BET) methods of investigation. Procedures for the AD-100 activation and promotion and the preparation of thin layers of the material to be studied and deposited on disk electrodes are described. The effect of the activation and promotion of carbon black on the surface and electrocatalytic activity of materials under study in the reduction of oxygen and hydrogen peroxide is shown. The ratio of constants of oxygen reduction directly to water and through intermediate formation of hydrogen peroxide is determined. A path for the oxygen reduction is discussed.