Synthesis of chiral salen Mn(III) complexes covalently linked to Re(I)-based photosensitizers

Two Mn(III)Re(I) binuclear complexes were prepared as catalyst-photosensitizer models, in which the chiral pyrrolidine salen Mn(III) unit was covalently bonded to an Re(I) bipyridyl carbonyl moiety via a carboxamide linkage. The spectral and electrochemical properties of the Mn(III)Re(I) complexes were studied.     

Synthesis,crystal structure,and fluorescence of an unexpected dialkoxo-bridged dinuclear copper(II) complex with bis(salen)-type tetraoxime

An unexpected dinuclear Cu(II) complex, [Cu₂(L²)₂] (H₂L^2?=?3-methoxysalicylaldehyde O-(2-hydroxyethyl)oxime), has been synthesized via complexation of Cu(II) acetate monohydrate with H₄L¹. Catalysis by Cu(II) results in unexpected cleavage of two N–O bonds in H₄L¹, giving a dialkoxo-bridged dinuclear Cu(II) complex possessing a Cu–O–Cu–O four-membered ring core instead of the usual bis(salen)-type tetraoxime Cu₃–N₄O₄ complex. Every complex links six other molecules into an infinite-layered supramolecular structure via 12 intermolecular C–H?···?O hydrogen bonds. Furthermore, Cu(II) complex exhibits purple emission with maximum emission wavelength λ_max?=?417?nm when excited with 312?nm.     

聚甲基丙烯酸羟乙酯负载手性Mn(III)salen配合物催化α-甲基苯乙烯的不对称环氧化反应(英文)

在手性Mn(III)salenCl配合物的5和5'位上引入氨基醇,将其通过轴配位作用负载于聚甲基丙烯酸羟乙酯(pHEMA)上,并用于离子液体[bmim]PF6中,催化α-甲基苯乙烯的不对称环氧化反应.结果表明,该催化剂表现出良好的催化活性和区域选择性,对映体过量值(ee)和产率可分别达80%～91%和84%～92%,循环使用5次后催化活性没有明显降低.这可归结为氨基醇和环己二胺中手性碳原子间相互协同作用.     

Radical Localization in a Series of Symmetric NiII Complexes with Oxidized Salen Ligands

Square‐planar nickel(II) complexes of salen ligands, N,N′‐bis(3‐tert‐butyl‐(5R)‐salicylidene)‐1,2‐cyclohexanediamine), in which R=tert‐butyl ( 1 ), OMe ( 2 ), and NMe₂ ( 3 ), were prepared and the electronic structure of the one‐electron‐oxidized species [ 1 – 3 ]^+. was investigated in solution. Cyclic voltammograms of [ 1 – 3 ] showed two quasi‐reversible redox waves that were assigned to the oxidation of the phenolate moieties to phenoxyl radicals. From the difference between the first and second redox potentials, the trend of electronic delocalization 1 ^+.> 2 ^+.> 3 ^+. was obtained. The cations [ 1 – 3 ]^+. exhibited isotropic g tensors of 2.045, 2.023, and 2.005, respectively, reflecting a lower metal character of the singly occupied molecular orbital (SOMO) for systems that involve strongly electron‐donating substituents. Pulsed‐EPR spectroscopy showed a single population of equivalent imino nitrogen atoms for 1 ^+., whereas two distinct populations were observed for 2 ^+.. The resonance Raman spectra of 2 ^+. and 3 ^+. displayed the ν_8a band of the phenoxyl radicals at 1612 cm^?1, as well as the ν_8a bands of the phenolates. In contrast, the Raman spectrum of 1 ^+. exhibited the ν_8a band at 1602 cm^?1, without any evidence of the phenolate peak. Previous work showed an intense near‐infrared (NIR) electronic transition for 1 ^+. (Δν_1/2=660 cm^?1, ε=21 700 M ^?1 cm^?1), indicating that the electron hole is fully delocalized over the ligand. The broader and moderately intense NIR transition of 2 ^+. (Δν_1/2=1250 cm^?1, ε=12 800 M ^?1 cm^?1) suggests a certain degree of ligand‐radical localization, whereas the very broad NIR transition of 3 ^+. (Δν_1/2=8630 cm^?1, ε=2550 M ^?1 cm^?1) indicates significant localization of the ligand radical on a single ring. Therefore, 1 ^+. is a Class III mixed‐valence complex, 2 ^+. is Class II/III borderline complex, and 3 ^+. is a Class II complex according to the Robin–Day classification method. By employing the Coulomb‐attenuated method (CAM‐B3LYP) we were able to predict the electron‐hole localization and NIR transitions in the series, and show that the energy match between the redox‐active ligand and the metal d orbitals is crucial for delocalization of the radical SOMO.     

水解动力学拆分3-(1-萘氧基)-1,2-环氧丙烷

研究了3-(1-萘氧基)-1,2-环氧丙烷[(R,S)-1]在Salen Co(Ⅲ)催化下的水解动力学拆分(HKR)。以转化率和ee值为指标,考察了催化剂用量、底物用量、反应温度、反应时间、溶剂种类等对HKR反应的影响。最佳HKR条件为:(R,S)-1 10 mmol,w[Salen Co(Ⅲ)]=0.75%,THF 1 mL,水0.5 eq,于25℃水解40 h,(R,S)-1的转化率为49.5%,(S)-1的ee为99.5%。     

Synthesis, characterization, DNA binding and cleavage studies of chiral Ru(II) salen complexes

Interaction of chiral Ru(II) salen complexes (S)-1 and (R)-1 with Calf Thymus DNA (CT-DNA) was studied by absorption spectroscopy, competitive binding study, viscosity measurements, CD measurements, thermal denaturation study and cleavage studies by agarose gel electrophoresis. The DNA binding affinity of (S)-1 (6.25 × 10³ M⁻¹) was found to be greater than (R)-1 (3.0 × 10³ M⁻¹). The antimicrobial studies of these complexes on five different gram (+)/(−) bacteria and three different fungal organisms showed selective inhibition of the growth of gram (+) bacteria and were not affective against gram (−) and fungal organisms. Further, the (S)-1 enantiomer inhibited the growth of organisms to a greater extent as compared to (R)-1 enantiomer.     

Synthesis and application of bimetallic chiral [Co(salen)]‐type complexes: a new catalytic approach to synthesis of optically pure β‐blockers via kinetic resolution of epichlorohydrin

A series of bimetallic chiral [Co(salen)]‐type complexes were successfully applied for the synthesis of optically pure β‐blockers via phenolic kinetic resolution (PKR) of racemic epichlorohydrin [2‐(chloromethyl)oxirane; ( ± )ECH]. The reaction proceeded readily at room temperature and consequently provided enantiomerically enriched corresponding α‐aryloxy alcohols with excellent enantioselectivities of up to 98% ee. The PKR method described in this work is highly efficient and straightforward strategy for the synthesis of chiral building blocks. Copyright © 2008 John Wiley & Sons, Ltd.     

Stoichiometric reduction of primary alkyl monohalides with electrogenerated nickel(I) salen: Formation of aldehydes

Addition of a stoichiometric amount of a primary alkyl monohalide (1-bromoalkane or 1-iodoalkane) to a solution of nickel(I) salen electrogenerated at a reticulated vitreous carbon cathode in dimethylformamide (DMF) containing 0.10 M tetramethylammonium tetrafluoroborate (TMABF₄) in the presence of water, followed by irradiation with a xenon arc lamp and exposure to oxygen (O₂), results in the formation of an aldehyde in substantial yield. Using cyclic voltammetry (CV) and controlled-potential electrolysis (CPE), we have explored the effects of light, temperature, water, and a proton donor on the process. Reduction of an alkyl monohalide in the presence of isotopically labeled reagents, along with CV–CPE experiments (in combination with ultraviolet–visible spectroscopy) and high-performance liquid chromatography (HPLC), suggests the possibility that O₂ interacts with an alkylnickel(II) species (which could arise from a two-to-one nickel(I) salen-to-alkyl monohalide reaction in the presence of water) to produce an aldehyde, which has a tendency to undergo a base-catalyzed aldol condensation. In addition to the aldehyde, other products (dimers, alkanes, and alkenes) are formed via classic radical reactions.     

Manganese(III) Salen Complex Immobilized on Fe3O4 Magnetic Nanoparticles: The Efficient,Green and Reusable Nanocatalyst

A new Fe₃O₄ magnetic nanoparticles supported manganese salen complex was successfully prepared by attaching manganese acetates to a novel N,N′‐bis(salicylidine)ethylenediamine ligand functionalized Fe₃O₄. The as‐prepared catalyst was characterized by TGA, XRD, FTIR, VSM, and TEM. It was found to be an efficient catalyst for the synthesis of benzopyranopyrimidines in aqueous medium. High catalytic activity and ease of recovery from the reaction mixture using external magnet, and several reuse times without significant losses in performance are additional eco‐friendly attributes of this catalytic system.     

Charge distribution in Mn(salen) complexes

The charge and spin distribution in manganese‐salen complexes were analyzed using different basis sets and density functionals. Five population analysis methods [Mulliken, Löwdin, Natural population analysis (NPA), atoms in molecules (AIM), and CHelpG] were used to characterize the charge distribution. Results show that NPA and AIM were the only methods capable of giving charges with the correct sign for all cases under study. According to the analysis of the natural charge and spin distributions, the salen ligand shows a complex behavior, counteracting the effect of the chloro and oxo ligands on the metal center. Furthermore, the presence of a chloride counter ion increases the oxo‐radical character of Oxo‐Mn(salen) complexes, which may play an important role in the rationalization of the catalytic properties of Mn(salen) complexes. © 2014 Wiley Periodicals, Inc.