Crystal and molecular structures of the Rh[(C2H5O)2PS2]3 and Co[(C6H5O)2PS2]3 chelate compounds

The crystal structures of the Rh[(EtO)₂PS₂]₃ (I) and Co[(PhO)₂PS₂]₃ (II) chelate compounds were determined from X-ray diffraction (XRD) data (CAD-4 diffractometer, MoK _β radiation, 1193 F _hkl , R = 0.0516 for I and 513 F _hkl , R = 0.0305 for II). Crystals I are monoclinic: a = 14.233(3) Å, b = 13.570(3) Å, c = 14.272(3) Å; β = 90.66(3)°, V = 2756.3(10) ų, Z = 4, ρ_calc = 1.587 g/cm³, space group C2/c. Crystals II are trigonal: a = 15.149(2) Å, c = 30.306(6) Å; V = 6023.2(16) ų, Z = 6, ρ_calc = 1.493 g/cm³, space group R3ˉ. Structures I and II consist of discrete mononuclear molecules. The coordination polyhedra of the M atoms (M = Rh, Co) are distorted octahedra formed by six sulfur atoms of three cyclic bidentate (RO)₂ PS₂⁻ ligands. Original Russian Text Copyright ? 2008 by R. F. Klevtsova, L. A. Glinskaya, and S. V. Larionov __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 49, No. 2, pp. 330–334, March–April, 2008.     

Hydroformylation of methyl-3-pentenoate over a phosphite ligand modified Rh/SiO2 catalyst

A phosphite ligand modified Rh/SiO2 catalyst has been developed for hydroformylation of internal olefins to linear aldehydes, which showed high activity and regioselectivity and could be separated easily by filtration after reaction in an autoclave. Effects of reaction temperature and syngas pressure on the performances of the catalyst in the reaction were also investigated.     

量子点在生物化学分析中的应用

量子点（quantumdots,QDs）由于其优异的光学和电学特性,作为新型的荧光试剂探针对生物大分子进行标记,成为近年来迅速发展的纳米材料在生化分析领域的重要应用之一。文章简述了量子点的基本特性,对制备和修饰量子点的各种方法进行比较总结,重点阐述量子点在生物化学分析中的新进展,尤其是对生物大分子的识别和标记作了详细的总结,并提出研究中存在的一些待解决的问题以及今后量子点的研究方向。     

Tunable Synthesis of Monofluoroalkenes and Gem-Difluoroalkenes via Solvent-Controlled Rhodium-Catalyzed Arylation of 1-Bromo-2,2-difluoroethylene

Divergent synthesis of fluorine-containing scaffolds starting from a suite of raw materials is an intriguing topic. Herein, we report the solvent-controlled rhodium-catalyzed tunable arylation of 1-bromo-2,2-difluoroethylene. The selection of the reaction solvents provides switchable defluorinated or debrominated arylation from readily available feedstock resources (both arylboronic acids/esters and 1-bromo-2,2-difluoroethylene are commercially available). This switch is feasible because of the difference in coordination ability between the solvent (CH₂Cl₂ or CH₃CN) and the rhodium center, resulting in different olefin insertion. This protocol allows the convenient synthesis of monofluoroalkenes and gem-difluoroalkenes, both of which are important scaffolds in the fields of medicine and materials. Moreover, this newly developed solvent-regulated reaction system can be applied to the site-selective dechlorinated arylation of trichloroethylene. Overall, this study provides a useful strategy for the divergent synthesis of fluorine-containing scaffolds and provides insight into the importance of solvent selection in catalytic reactions.     

Density functional theory calculations of novel Rh(I) diphosphinite catalysts

Novel Rh(I) diphosphinite catalysts [Rh((R,R)-3,4-(bis(O-diphenylphosphino)-1,2,5,6-tetra-O-methyl-chiro-inositol)]+ ([Rh-CANDYPHOS]+) and [Rh((R,R)-3,4-(bis(O-diphenylphosphino)-1,2,5,6-tetra-O-ethyl-chiro-inositol)]+ ([Rh-EtCP]+) have been prepared utilizing naturally-occurring resources. Potential energy surfaces for the catalyzed asymmetric hydrogenation of the prochiral enamides methyl-(Z)-α-acetamido cinnamate, methyl-(Z)-α-acetamido cinnamic acid and dimethyl itaconate have been surveyed using density function theory (DFT) methods. Key transition states were identified from previous [Rh((R,R)-DUPHOS)]+ studies for the two diastereoisomeric manifolds 1 and 2. Transition state energies were found starting from models based on (1) the X-ray structure of the active complex (CANDYPHOS)(η⁴-(Z,Z)-cyclo-octa-1,5-diene)-rhodium(I) tetrafluoroborate CHCl₃ solvate [3] and (2) models in which the complex (without substrate) started with C2 molecular symmetry. The difficulties encountered in calculations of the transition state energies of large cations are outlined and limitations noted. Transition state enthalpy values are compared with the observed experimental free energy differences results and previous studies 1 and 2. The predictive aspects of the calculations appear to be limited with the starting models playing an important part in the absolute value of the final energies.     

Ruthenium(II), rhodium(III) and iridium(III) based effective catalysts for hydrogenation under aerobic conditions

The new cationic mononuclear complexes [(η⁶-arene)Ru(Ph-BIAN)Cl]BF₄ [η⁶-arene = benzene (1), p-cymene (2)], [(η⁵-C₅H₅)Ru(Ph-BIAN)PPh₃]BF₄ (3) and [(η⁵-C₅Me₅)M(Ph-BIAN)Cl]BF₄ [M = Rh (4), Ir (5)] incorporating 1,2-bis(phenylimino)acenaphthene (Ph-BIAN) are reported. The complexes have been fully characterized by analytical and spectral (IR, NMR, FAB-MS, electronic and emission) studies. The molecular structure of the representative iridium complex [(η⁵-C₅Me₅)Ir(Ph-BIAN)Cl]BF₄ has been determined crystallographically. Complexes 1–5 effectively catalyze the reduction of terephthaldehyde in the presence of HCOOH/CH₃COONa in water under aerobic conditions and, among these complexes the rhodium complex [(η⁵-C₅Me₅)Rh(Ph-BIAN)Cl]BF₄ (4) displays the most effective catalytic activity.     

CdTe量子点同步荧光法测定人血清白蛋白

以巯基乙酸(HS-CH2COOH)为稳定剂,水相中合成了CdTe量子点.在pH 6.40的0.002 mol/L KH2PO4-Na2HPO4缓冲溶液中,固定波长差为220 nm时一定量蛋白质的加入能明显增强量子点的同步荧光强度,并且荧光峰强度增加值与血清白蛋白浓度间存在良好的线性关系,据此建立了一种高灵敏度的测定微量蛋白质的方法.该方法测定人血清白蛋白的线性范围为0.08～2.80 μg/mL,检出限为0.032 μg/mL,10次重复测定1.80 μg/mL的血清白蛋白相对标准偏差为1.1%,已用于实际样品的测定.     

Highly Efficient and Chemoselective Tandem Hydroformylation-Hydrogenation of Alkenes to Alcohols over g-CN Supported Bimetallic Rh and Co Nanoparticles Catalysts

The objective of the tandem hydroformylation-hydrogenation of alkenes to corresponding alcohols was to design an efficient and stable heterogeneous catalyst. To this end, a series of novel heterogeneous graphitic carbon nitride (g-CN) supported bimetallic Rh−Co nanoparticle catalysts (Rh−Co/g-CN) were prepared and subsequently studied for this one-pot two-step reaction. The lamellar structure makes Rh and Co nanoparticles with diameters of <1 nm and 20 nm, respectively, homogeneously deposited on the surface of g-CN layers, exhibit remarkable conversion of styrene (99.9 %) and chemoselectivity for alcohol (87.8 %). More importantly, Co nanoparticles are found to play an important role in the improvement of the chemoselectivity for alcohol due to the formation of catalytic active species [HCo(CO)_y]. Besides the detailed investigation of the catalytic properties of Rh−Co/g-CN under different reaction conditions, the reuse of Rh−Co/g-CN was conducted for five times and no evident decrease in the activity and chemoselectivity was observed. Therefore, we expect that this work could offer an initial insight into g-CN-based heterogeneous catalyst on the tandem hydroformylation-hydrogenation reaction.     

杂环化聚丙烯亚胺树状聚合物负载钌铑双金属纳米粒子的制备及在催化丁腈橡胶氢化中的应用

以十五元三烯氮杂大环改性的不同代数聚丙烯亚胺树状聚合物(Gn-M,n=2,3,4)为模板,通过共络合-还原方法制备了一系列钌/铑双金属纳米粒子[Gn-M(RuxRh100-x)DTNs,x为Ru摩尔分数],并将其应用于丁腈橡胶(NMR)的催化氢化.用紫外-可见光谱(UV-Vis)、X射线衍射分析(XRD)及X射线能谱(EDS)表征DTNs的金属组成和结构,结果表明,DTNs上的双金属离子被还原成金属单质并负载于Gn-M上;粒度分析结果表明,G2-M(Ru50Rh50),G3-M(Ru50Rh50)和G4-M(Ru50Rh50)DTNs的平均粒径分别为7.5,8.1和4.5 nm.凝胶测试及核磁共振波谱(1H NMR)结果表明,Ru/Rh DTNs催化剂对丁腈橡胶的催化氢化反应具有良好的选择性.当以G4-M(Ru30Rh70)DTNs为催化剂时,NBR的氢化度最高可达99.51%,循环使用2次后,丁腈橡胶的氢化度仍可达到90.58%.     

Resonance energy transfer between ZnCdHgSe quantum dots and gold nanorods enhancing photoelectrochemical immunosensing of prostate specific antigen

Gold nanorods (AuNRs) integrated with ZnCdHgSe near-infrared quantum dots (AuNRs-ZnCdHgSe QDs) were successfully synthesized and characterized by transmission electron microscope, X-ray photoelectron spectroscopy, and X-ray diffraction. A glassy carbon electrode was decorated with the aforementioned AuNRs-ZnCdHgSe QDs nanocomposite, which provides a biocompatible interface for the subsequent immobilization of prostate specific antibody (anti-PSA). After being successively treated with glutaraldehyde vapor and bovine serum albumin solution, a photoelectrochemical immunosensing platform based on anti-PSA/AuNRs-ZnCdHgSe QDs/GCE was established. The photocurrent response of ZnCdHgSe QDs was tremendously improved by AuNRs due to the effect of resonance energy transfer which can be deduced from the dependence of the enhanced efficiency on the AuNRs with different length-to-diameter ratios and spectral absorption characteristics. A maximum photocurrent was obtained when the absorption spectrum of AuNRs matched well with the emission spectrum of ZnCdHgSe QDs. A photoelectrochemical immunosensor for prostate specific antigen (PSA) was achieved by monitoring the photocurrent variation. The photocurrent variation before and after being interacted with PSA solution exhibits a good linear relationship with the logarithm of its concentration (logc_PSA) in the range from 1.0 pg mL⁻¹ to 50.0 ng mL⁻¹. The detection limit of this photoelectrochemical immunosensor is able to reach 0.1 pg mL⁻¹ (S/N = 3). Determining PSA in clinical human serum was also demonstrated by using the developed anti-PSA(BSA)/AuNRs-ZnCdHgSe QDs/GCE electrode. The results were comparable with those obtained from an enzyme-linked immunosorbent assay method.