金属卟啉催化烯烃环氧化及反应机理研究*

本文就铁卟啉及锰卟啉模拟酶体系近年来在催化烯烃环氧化反应机理方面的最新研究成果进行了详细阐述。均相催化剂固载化技术的应用,使金属卟啉配合物担载于无机载体上克服了卟啉的二聚、催化剂再生等难题,有力地推动了金属卟啉配合物应用研究的发展。     

乙酰糖基金属卟啉的合成及其对烷烃温和氧化的选择性催化作用

由吡咯和葡萄糖取代苯甲醛直接缩合制备了两种葡萄糖取代卟吩,四(邻位乙酰葡萄糖氧代苯基)卟吩和四(间位乙酰葡萄糖氧代苯基)卟吩,它们进一步金属化合成了四种葡萄糖金属卟啉,氯化四(邻位乙酰葡萄糖氧代苯基)卟吩合铁、氯化四(间位乙酰葡萄糖氧代苯基)卟吩合铁、氯化四(邻位四乙酰葡萄糖氧代苯基)卟吩合锰和氯化四(间位乙酰葡萄糖氧代苯基)卟吩合锰。它们的结构由紫外-可见光谱、元素分析和核磁共振证实。研究了这些葡萄糖取代金属卟啉对亚碘酰苯常温常压下氧化异戊烷反应的选择性催化作用。研究表明,糖基金属卟啉催化异戊烷端基碳氢键的氧化,对一级碳氢键表现出专一性催化作用。非糖基金属卟啉催化异戊烷二级和三级碳氢键的氧化。与非糖基金属卟啉比较,糖基金属卟啉对烷烃羟基化反应的催化行为更接近细胞色素P-450单充氧酶。     

具有抗多种活性氧酶功能的金属卟啉的研究—钌卟啉仿酶活性测试

二价金属钌卟啉[Ru^Ⅱ(4-Cl-TPP)(CO)](1),[Ru^Ⅱ(4-MeO-TPP)(CO)](2),[Ru^Ⅱ(C,4,5-MeO-TPP)(CO)](3)和六价金属钌卟啉[Ru^Ⅵ（4Cl-TPP)(O)2](4),[Ru^Ⅵ(4-MeO-TPP)(O)2](5),[Ru^Ⅵ(3,4,5-MeO-TPP)(O)2](6)被合成,配合物1－6作为超氧化物歧化酶（SOD）和过氧化氢酶（CAT）功能模拟酶被测试,核黄素－蛋胺酸光照法证实,钌啉啉在不同浓度范围内有催化歧化O^.-2的作用,分光光度法证实能催化H2O2分解,用小鼠肝匀浆法测度试结果表明：金属钌啉具有良好的抗脂质过氧化作用,提出了金属钌卟啉在催化歧化超氧阴离子自由基（O^.-2)和催化分解过氧化氢（H2O2）协同过程中的可能机理,并讨论了卟啉环上不同取代基对催化活性的影响。     

SCF perturbation calculations on metalloporphyrins

The influence of metal ion on the oxidation and ionisation potentials of metalloporphyrins is investigated by the simple electrostatic model using SCF perturbation theory. The zero order wavefunctions are obtained from PPP and CNDO/2 methods. The wide variations in redox potentials with metal and the relative insensitivity of the optical transitions with metal are very well accounted for by the perturbation approach.     

Solvent effects in molecular complexes of porphyrins and metalloporphyrins

The apparent stability constants for porphyrin and metalloporphyrin complexes with an electron acceptor have been determined in mixed solvents. The variation of the apparent stability with solvent composition is evaluated in terms of solvation of the complex and reactant species and in terms of the exclusion of the solvent from the solvation sheath of the reactants, according to the equilibrium AS _a +DS _b =CS _x +yS.     

Some peculiarities of π—π interactions between tetraphenylporphine metal complexes and aromatic solvents

The — complexes of metal tetraphenylporphinates with benzene, toluene, and xylenes were characterized by means of thermogravimetry. The ability of metalloporphyrins to form — complexes with certain -donor molecules depends largely on the -acceptor capacity of the macroheterocycle, and on the peculiarities of the metal—porphyrin coordinative linkage. Stoichiometry, energy parameters, and thermal stability of the - complexes of metalloporphyrins with various aromatic ligands are determined to a great extent by the molecular structure of solvents.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp.850–853, May, 1993.     

乙酰葡萄糖氧代金属卟啉的合成及其对环己烷羟基化反应的催化作用

由吡咯和葡萄糖取代苯甲醛直接缩合制备了两种葡萄糖取代卟吩:四(邻位乙酰葡萄糖氧代苯基)卟吩和四(间位乙酰葡萄糖氧代苯基)卟吩,进一步金属化合成了4种葡萄糖金属卟啉:氯化四(邻位乙酰葡萄糖氧代苯基)卟吩合铁、氯化四(间位乙酰葡萄糖氧代苯基)卟吩合铁、氯化四(邻位四乙酰葡萄糖氧代苯基)卟吩合锰和氯化四(间位乙酰葡萄糖氧代苯基)卟吩合锰.它们的结构由紫外-可见光谱、核磁共振和元素分析证实.研究了这些葡萄糖取代金属卟啉对亚碘酰苯常温常压下氧化环己烷反应的催化作用.研究结果表明,4种糖基金属卟啉催化下的环己烷反应产率和反应速率都比一般金属卟啉高.反应动力学分析表明,在常温常压下,糖基金属卟啉催化下的环己烷氧化反应具有酶催化反应的动力学关系.     

金属卟啉核酸定位断裂剂的设计及氧化断裂研究

金属卟啉连接到一些特殊基团如寡聚核苷酸、蛋白肽链、吖啶等上时, 可达到对DNA 的定位断裂, 这在核酸探针及抗癌剂的设计中具有重要的作用。本文就近年来国内外在金属卟啉对DNA 的定位识别及在Ph IO、KHSO 5、O 2? 还原剂等存在下, 对DNA 定位氧化断裂等方面的研究进展进行了综述, 可供该方向的研究人员参考。     

Molecular Dyads Comprising Metalloporphyrin and Alkynylplatinum(II) Polypyridine Terminal Groups for Use as a Sensitizer in Dye‐Sensitized Solar Cells

A new class of molecular dyads comprising metalloporphyrin‐linked alkynylplatinum(II) polypyridine complexes with carboxylic acids as anchoring groups has been designed and synthesized. These complexes can sensitize nanocrystalline TiO₂ in dye‐sensitized solar cell (DSSC) studies. The photophysical, electrochemical, and luminescence properties of the complexes were studied and their excited‐state properties were investigated by nanosecond transient absorption spectroscopy, with the charge‐separated [Por^.??{(C?C)Pt(tBu₃tpy)}^.+] state observed upon excitation. Excited‐state redox potentials were determined; the electrochemical data supports the capability of the complexes to inject an electron into the conduction band of TiO₂. The complexes sensitize nanocrystalline TiO₂ and exhibited photovoltaic properties, as characterized by current–voltage measurements under illumination of air mass 1.5 G sunlight (100 mWcm^?2). A DSSC based on one of the complexes showed a short‐circuit photocurrent of 10.1 mAcm^?2, an open‐circuit voltage of 0.64 V, and a fill factor of 0.52, giving an overall power conversion efficiency of 3.4 %.     

Systematic Selection of Metalloporphyrin‐Based Catalysts for Oxygen Reduction by Modulation of the Donor–Acceptor Intermolecular Hardness

Incisive modulation of the intermolecular hardness between metalloporphyrins and O₂ can lead to the identification of promising catalysts for oxygen reduction. The dependency of the electrocatalytic reduction of O₂ by metalloporphyrins on the nature of the central metal yields a volcano‐type curve, which is rationalized to be in accordance with the Sabatier principle by using an approximation of the electrophilicity of the complexes. By using electrochemical and UV/Vis data, the influence of a selection of meso‐substituents on the change in the energy for the π→π* excitation of manganese porphyrins was evaluated allowing one to quantitatively correlate the influence of the various ligands on the electrocatalysis of O₂ reduction by the complexes. A manganese porphyrin was identified that electrocatalyzes the reduction of oxygen at low overpotentials without generating hydrogen peroxide. The activity of the complex became remarkably enhanced upon its pyrolysis at 650 °C.