Synthesis and fluorescent properties of Eu and Tb complexes with a series of new diamide ligands

A series of new diamide ligands were introduced into the complexes of Eu(NO₃)₃ and Tb(NO₃)₃ so as to improve the fluorescent properties. The fluorescent properties of the resulting complexes were investigated. It was found that the complexes subject to the excitation of UV light showed characteristic emission of europium and terbium ions, in particular, the Tb complexes had very much intense fluorescence.     

Coordinatively unsaturated molybdenum complexes with chelating cycloheptatrienyl-phosphane ligands and their use in transition metal catalysis

The synthesis of the tetrahydroborate complex [(2-iPr₂PC₆H₄-η⁷-C₇H₆)Mo(η²-BH₄)(P–Mo)] 3 containing the linked cycloheptatrienyl-phosphane ligand [2-(diisopropylphosphanyl)phenyl]cycloheptatrienyl is described, which provides the possibility to generate the 14-electron complex [(2-iPr₂PC₆H₄-η⁷-C₇H₆)Mo(P–Mo)]⁺ (4) on treatment with dimethylanilinium salts such as [HNMe₂Ph][BPh₄]. Generation of (4)BPh₄ in the presence of 2,6-dimethylphenyl isocyanide, 2,5-norbornadiene or phenylacetylene affords the diisocyanide complex (5a)BPh₄, the diolefin complex (5b)BPh₄ and the alkyne complex (6)BPh₄, respectively. The latter complex can be used for the catalytic oligomerization of phenylacetylene affording predominantly the cyclotrimers 1,3,5- and 1,2,4-triphenylbenzene.     

Ring‐opening metathesis polymerization of norbornene catalyzed by tantalum and niobium complexes with chelating O‐donor ligands

BACKGROUND: In comparison with group 6 transition metals, such as tungsten and molybdenum, and group 8 metal ruthenium, group 5 metal‐based catalysts for ring‐opening metathesis polymerization (ROMP) have remained much less studied. The few reported ROMP catalysts of group 5 metals require multiple reaction steps to be synthesized, and are highly sensitive to air and moisture. RESULTS: A series of pentavalent tantalum and niobium complexes having catecholato, tropolonato, hinokitiolato, biphenolato and binaphtholato ligands were prepared and their catalytic activities for the ROMP of norbornene (NBE) were studied in the presence of trialkylaluminium as a co‐catalyst. Among these complexes, the tantalum complexes showed high activity upon activation with Buⁱ₃Al. In sharp contrast, the niobium complexes were effectively activated with Me₃Al. The polymers obtained with these complexes had high molecular weights (M_n > 10⁵ g mol⁻¹) and relatively narrow molecular weight distributions (M_w/M_n ≈ 2). CONCLUSION: We found that easily accessible and relatively stable tantalum and niobium complexes with such chelating O‐donor ligands showed high catalytic activity for ROMP of NBE depending on the kind of co‐catalyst. These findings could contribute to future development of ROMP catalysts. Copyright © 2008 Society of Chemical Industry     

Electrochemical bromination and oxidation of alkyl aromatic compounds by two-phase electrolysis

A simple, regioselective, environmentally clean and economical method for the preparation of side chain/ ring brominated aromatic compounds is reported in 70–98% yield by an electrochemical method using two phase electrolysis technique. Electrochemical reactions were carried out using aqueous 25–50 wt% sodium bromide containing catalytic amount (5 wt%) of hydrobromic acid as an aqueous phase and chloroform containing alkyl aromatic compounds as an organic phase, at a temperature of 0–30 °C in an undivided cell. The same two-phase electrolytic system can be used for the oxidation of benzylic alcohols to the corresponding benzaldehydes in 80–94% yield without over oxidation to carboxylic acids. The advantage of this very mild procedure is a room temperature reaction used with an undivided cell. Excellent conversions are observed. After completion of alcohol oxidation the electrolyte can be reused for a number of times, demonstrating “spent reagent” free electro organic reaction as an attractive one. In the case of side chain/ring bromination of alkyl aromatic compounds, the electrolyte can be reused after making up the concentration of the electrolyte with 47 wt% HBr solution. In some cases homogeneous electrolysis is applied, where the two-phase electrolysis did not work. Styrene epoxidation and α-bromination of ketones underwent homogeneous electrolysis at room temperature without any catalyst. The reaction was performed in CH₃CN-water (3: 2) using equimolar amount of NaBr as an electrolyte to get 68% of styrene epoxide. Use of an ionic liquid 1-butyl 3-methyl imidazolium bromide (Bmim) Br, instead of NaBr improved the yield and current efficiency of styrene epoxide to 86%.     

Reactions of alkyl radicals with metal powders immersed in aqueous solutions

The mechanism of dehalogenation is investigated in reactions between alkyl radicals and metal powders immersed in aqueous solutionsOriginal Russian Text Copyright © 2005 by Fizika i Khimiya Stekla, Rusonik, Zidky, Cohen, Meyerstein.     

Titanium complexes of chelating dianionic amine bis(phenolate) ligands: an extra donor makes a big difference

Two dianionic amine bis(phenolate) ligands are introduced and their reactions with titanium tetra(iso-propoxide) studied; ligand 1 having a single N-donor group leads exclusively to a homoleptic Lig₂Ti type complex whereas ligand 3 having an additional N-donor on a side arm leads exclusively to a LigTi(OPrⁱ)₂ type complex.     

General aspects of ethylene polymerization by d0 and d0f n transition metals

We present a generalized view of d⁰and d⁰f ⁿ metal complexes as olefin polymerization catalysts from computational studies of the {L}M–C₂H₅ ^(0,+,2+)-fragments (M = Sc(III), Y(III), La(III), Lu(III), Ti(IV), Zr(IV), Hf(IV), Ce(IV), Th(IV) and V(V); L = NH–(CH)₂–NH^2- {1}, N(BH₂)–(CH)₂–(BH₂)N^2- {2}, O–(CH)₃–O^- {3}, Cp₂ ^2- {4}, NH–Si(H₂)–C₅H₄ ^2- {5}, {(oxo)(O–(CH)₃–O)}^3- {6}, (NH₂)₂ ^2- {7}, (OH)₂ ^2- {8}, (CH₃)₂ ^2- {9}, NH–(CH₂)₃–NH^2- {10} and O–(CH₂)₃–O^2- {11}). This revised version was published online in June 2006 with corrections to the Cover Date.     

Ethylene polymerization catalyzed by diamide complexes of Ti(IV) and Zr(IV)

In this research, we describe the application of the complexes o‐C₆H₄(NSiMe₃)₂ZrCl₂ ( 1 ), o‐C₆H₄(NSiMe₃)₂TiBr₂ ( 2 ), o‐C₆H₄(NSiMe₃)₂TiCl₂ ( 3 ), C₂H₄(NSiMe₃)₂ZrCl₂ ( 4 ), in the ethylene polymerization with different Al/M ratios and temperatures. These complexes presented significant catalytic activities in the presence of methyaluminoxane (MAO) as cocatalyst and toluene as solvent, producing high molecular weight linear polyethylenes. Zirconium complexes were more active at 60°C and titanium complexes at 40°C. Zirconium complex ( 1 ) showed the best values of activity (347 kg PE/mol Zr h atm) for Al/Zr ratio of 340 and 60°C of temperature. In ethylene‐1‐hexene copolymerization, the best result was also reached with catalyst 1 , at the same conditions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Novel conventional and chelating anion exchange resins with amino ligands for sorption of silver

ABSTRACT

The polymeric resins containing diethylenetriamine, tetraethylenepentamine, 2-(diethylamino)ethanol, 1-methylimidazole, and 1,2-dimethylimidazole ligands have been synthesized from vinylbenzyl chloride-divinylbenzene copolymers and used in the removal of Ag(I) from chloride solution. The best Ag(I) sorption was reached in the case of 1-methylimidazole resin. Resins retain their capacity towards Ag(I) in five consecutive sorption/desorption cycles. The resins with imidazole ligands were highly selective for Ag(I) from synthetic chloride solution and they did not sorb chloride complexes of Cu(II). Additionally, the recovery of Ag(I) was tested from real chloride solution coming from leaching of the copper concentrate from Lubin Concentrator (KGHM Polska Mied? S.A.).     

离子液体支撑液膜用于分离混合芳烃的研究

利用不同离子液体制备离子液体"充填型"支撑液膜,将其用于混合芳烃中对二甲苯的蒸汽渗透膜分离实验,比较了不同离子液体、不同支撑底膜、原料中对二甲苯的含量、操作温度等因素对分离性能的影响。结果表明,在40℃温度下,[Bmim][BF4]填充PVDF膜形成的支撑液膜对对二甲苯体积分数为60%的混合芳烃渗透通量为59.5 g/(m2·h),分离因子达16.5;经过90 h的实验测定,支撑液膜分离性能稳定。离子液体支撑液膜的蒸汽渗透过程能够实现从混合芳烃中将对二甲苯分离。     

HZSM-5固载离子液体催化合成烷基糖苷及其动力学

以自制苯并噻唑离子液体([HBth]HSO4)为活性组分,HZSM-5分子筛为载体,通过过量溶剂浸渍法制备了固载型苯并噻唑离子液体催化剂([HBth]HSO4/HZSM-5),并用于催化合成烷基糖苷.通过FTIR、原位红外光谱、TG、N2物理吸附-脱附、FESEM-EDS和XRD对催化剂结构进行了表征.结果表明,[HBth]HSO4被成功地引入到HZSM-5的表面及孔道内.当催化剂用量为1.5％(以葡萄糖与辛醇的总质量为基准,下同)、反应温度为105℃、n(正辛醇):n(无水葡萄糖)=6:1时,辛基糖苷得率达148.86％.底物拓展及催化剂稳定性结果表明,[HBth]HSO4/HZSM-5对烷基糖苷及其衍生物都具有良好的催化效果,且催化剂能稳定循环使用4次.活性组分流失是催化剂失活的主要原因.通过对烷基糖苷催化合成机理和动力学的研究,确定了动力学方程.     

HZSM-5固载离子液体催化合成烷基糖苷及其动力学

以自制苯并噻唑离子液体([HBth]HSO4)为活性组分,HZSM-5分子筛为载体,通过过量溶剂浸渍法制备了固载型苯并噻唑离子液体催化剂([HBth]HSO4/HZSM-5),并用于催化合成烷基糖苷.通过FTIR、原位红外光谱、TG、N2物理吸附-脱附、FESEM-EDS和XRD对催化剂结构进行了表征.结果表明,[HBth]HSO4被成功地引入到HZSM-5的表面及孔道内.当催化剂用量为1.5％(以葡萄糖与辛醇的总质量为基准,下同)、反应温度为105℃、n(正辛醇):n(无水葡萄糖)=6:1时,辛基糖苷得率达148.86％.底物拓展及催化剂稳定性结果表明,[HBth]HSO4/HZSM-5对烷基糖苷及其衍生物都具有良好的催化效果,且催化剂能稳定循环使用4次.活性组分流失是催化剂失活的主要原因.通过对烷基糖苷催化合成机理和动力学的研究,确定了动力学方程.     

HZSM-5固载离子液体催化合成烷基糖苷及其动力学

以自制苯并噻唑离子液体([HBth]HSO4)为活性组分,HZSM-5分子筛为载体,通过过量溶剂浸渍法制备了固载型苯并噻唑离子液体催化剂([HBth]HSO4/HZSM-5),并用于催化合成烷基糖苷.通过FTIR、原位红外光谱、TG、N2物理吸附-脱附、FESEM-EDS和XRD对催化剂结构进行了表征.结果表明,[HBth]HSO4被成功地引入到HZSM-5的表面及孔道内.当催化剂用量为1.5％(以葡萄糖与辛醇的总质量为基准,下同)、反应温度为105℃、n(正辛醇):n(无水葡萄糖)=6:1时,辛基糖苷得率达148.86％.底物拓展及催化剂稳定性结果表明,[HBth]HSO4/HZSM-5对烷基糖苷及其衍生物都具有良好的催化效果,且催化剂能稳定循环使用4次.活性组分流失是催化剂失活的主要原因.通过对烷基糖苷催化合成机理和动力学的研究,确定了动力学方程.     

Reactions of late transition metal complexes with molecular oxygen

Limited natural resources, high energy consumption, economic considerations, and environmental concerns demand that we develop new technologies for the sustainable production of chemicals and fuels. New methods that combine the selective activation of C-H bonds of hydrocarbons with oxidation by a green oxidant such as molecular oxygen would represent huge advances toward this goal. The spectacular selectivity of transition metals in cleaving C-H bonds offers the potential for the direct use of hydrocarbons in the production of value-added organics such as alcohols. However, the use of oxygen, which is abundant, environmentally benign, and inexpensive (particularly from air), has proven challenging, and more expensive and less green oxidants are often employed in transition-metal-catalyzed reactions. Advances in the use of oxygen as an oxidant in transition-metal-catalyzed transformations of hydrocarbons will require a better understanding of how oxygen reacts with transition metal alkyl and hydride complexes. For alkane oxidations, researchers will need to comprehend and predict how metals that have shown particularly high activity and selectivity in C-H bond activation (e.g. Pt, Pd, Rh, Ir) will react with oxygen. In this Account, we present our studies of reactions of late metal alkyls and hydrides with molecular oxygen, emphasizing the mechanistic insights that have emerged from this work. Our studies have unraveled some of the general mechanistic features of how molecular oxygen inserts into late metal hydride and alkyl bonds along with a nascent understanding of the scope and limitations of these reactions. We present examples of the formation of metal hydroperoxide species M-OOH by insertion of dioxygen into Pt(IV)-H and Pd(II)-H bonds and show evidence that these reactions proceed by radical chain and hydrogen abstraction pathways, respectively. Comparisons with recent reports of insertion of oxygen into other Pd(II)-H complexes, and also into Ir(III)-H and Rh(III)-H complexes, point to potentially general mechanisms for this type of reaction. Additionally, we observed oxygen-promoted C-H and H-H reductive elimination reactions from five-coordinate Ir(III) alkyl hydride and dihydride complexes, respectively. Further, when Pd(II)Me(2) and Pt(II)Me(2) complexes were exposed to oxygen, insertion processes generated M-OOMe complexes. Mechanistic studies for these reactions are consistent with radical chain homolytic substitution pathways involving five-coordinate M(III) intermediates. Due to the remarkable ability of Pt(II) and Pd(II) to activate the C-H bonds of hydrocarbons (RH) and form M-R species, this reactivity is especially exciting for the development of partial alkane-oxidation processes that utilize molecular oxygen. Our understanding of how late transition metal alkyls and hydrides react with molecular oxygen is growing rapidly and will soon approach our knowledge of how other small molecules such as olefins and carbon monoxide react with these species. Just as advances in understanding olefin and CO insertion reactions have shaped important industrial processes, key insight into oxygen insertion should lead to significant gains in sustainable commercial selective oxidation catalysis.     

过氧钒有机配合物及其在有机合成中的应用

对过氧有机钒配合物的合成及其在有机合成中的应用作一简要综述.     

Induction of DNA-double-strand breaks by auger electrons from 99mTc complexes with DNA-binding ligands

The potential of certain Auger electron emitting nuclides for systemic radiotherapeutic applications has recently gained much attention. In particular, the ability of several nuclides, including 111In, 125I, and 123I, to induce DNA double-strand breaks (dsb), a good indicator of cytotoxicity, has been extensively studied. However, this ability has never previously been shown experimentally for 99mTc, which, besides the well-known gamma radiation that is used for diagnostic applications, also emits an average of 1.1 conversion electrons and 4 Auger or Coster-Kronig electrons per decay. Owing to the short range of Auger electrons, the radionuclide needs to be located very close to the DNA for dsb to occur. We synthesized two cationic 99mTcI-tricarbonyl complexes with pendant DNA binders, pyrene and anthraquinone. The X-ray crystal structures of the two complexes could be elucidated. Linear dichroism and UV/Vis spectroscopy revealed that the complex with pyrene intercalates DNA with a stability constant, K, of 1.1 x 10(6) M(-1), while the analogous complex with anthraquinone interacts with DNA in a groove-binding mode and has an affinity value of K=8.9 x 10(4) M(-1). We showed with phiX174 double-stranded DNA that the corresponding 99mTc complexes induce a significant amount of dsb, whereas non-DNA-binding [TcO4]- and nonradioactive Re compounds did not. These results indicate that the Auger electron emitter 99mTc can induce dsb in DNA when decaying in its direct vicinity and this implies potential for systemic radiotherapy with 99mTc complexes.     

Extraction of metal ions with non-fluorous bipyridine derivatives as chelating ligands in supercritical carbon dioxide

Three new non-fluorous bipyridine derivatives, bis(2-(2-butoxyethoxy)ethyl)-2,2′-bipyridine-4,4′-dicarboxylate (ligand 1), bis(2-(2-ethoxyethoxy)ethyl)-2,2′-bipyridine-4,4′-dicarboxylate (ligand 2), and bis(2-butoxyethyl)-2,2′-bipyridine-4,4′-dicarboxylate (ligand 3), were synthesized as chelating ligands to remove metal ions from solid matrix into supercritical CO₂ (scCO₂). These produced compounds 1-3 showed considerable solubilities in scCO₂ (8.0 g/l, 4.8 g/l, 7.8 g/l for ligands 1-3 at 313 K, respectively) and the tested solubility data were then calculated and correlated with semiempirical model at different pressures and temperatures, which showed satisfactory agreement with each other and the average absolute relative deviation were in the range of 0.1-28.3%. The effects of pressure, temperature, time, and ligand to metal ratio (5:1 to 75:1) on the extraction efficiency of metal ions were also systematically investigated. The extraction efficiency was 100% for Ni²⁺ and 95.9% for Cu²⁺ in scCO₂ with the system of ligand 1, ultrapure water, and perfluoro-1-octanesulfonic acid tetraethylammonium salt (PFOAT) under the optimized conditions (25 MPa, 313 K, 90 min, and ligand to metal ratio of 10). Although all ligands exhibited good efficiency for Ni²⁺ (>85%) and Cu²⁺ (>70%) extraction, the extraction of mixed metal ions indicated that the bipyridine derivatives had low selectivity. Finally, the detailed calculation results exhibited that the extraction constants (K_ex) of the metal ions increased with the increase of the extraction efficiency in the same extraction system for each same metal ion.     

固载型过渡金属卟啉催化氧化烷烃的研究进展

对固载型过渡金属卟啉在多相催化体系中氧化烷烃的现状进行综述，重点介绍了有机担体如阴离子交换树脂，无机担体二氧化硅、蒙脱土上固载金属卟啉的方法及催化氧化烷烃的效果。固载金属卟啉容易分离，一定条件下，催化剂的寿命较之液相催化剂有所延长，但是也存在反应诱导期长、催化剂制备复杂及容易从担体流失等缺点。     

钒的有机配合物及其抗糖尿病活性

本文对于含有V-O、V-N、V-S配位模型的有机钒配合物,根据它们的配位体类型,对其合成设计、抗糖尿病活性作出简要综述。     

The rate of ethylene polymerization initiated by various chelating tertiary diamine : n-butyllithium complexes

The initial rates of ethylene polymerization initiated by 13 chelating tertiary diamine:n-butyllithium complexes were determined under a standard set of conditions. Complexes of the cyclic diamines 1,2-dipyrrolidinoethane, sparteine, and 1,2-dipiperidinoethane resulted in higher polymerization rates and larger ultimate polymer yields than did complexes of acyclic diamines such as N,N,N′,N′-tetramethylethylenediamine. The rates of polymerization and also the polymer yields were also strongly affected by the length of the chain segment connecting the two amino groups in the diamine. Two carbon segments were superior to three carbon segments which were better than one or four carbon segments. The decomposition rate of n-butyllithium was also strongly accelerated by the presence of many of these diamines.