The reaction of selenium dichloride with divinyl sulfide

A synthesis of novel selenium heterocycles based on the reaction of selenium dichloride with divinyl sulfide has been described. At −50 °C the reaction affords 2,6-dichloro-1,4-thiaselenane in quantitative yield. At room temperature the reaction gives 2,6-dichloro-1,4-thiaselenane and 5-chloro-2-chloromethyl-1,3-thiaselenolane. Upon standing in chloroform solution, 2,6-dichloro-1,4-thiaselenane undergoes spontaneous rearrangement to 5-chloro-2-chloromethyl-1,3-thiaselenolane. Under the action of pyridine, 2,6-dichloro-1,4-thiaselenane is converted to 2-chloromethyl-1,3-thiaselenole in 95% yield.     

Highly-efficient and recyclable nanosized MCM-41 anchored palladium bipyridyl complex-catalyzed coupling of acyl chlorides and terminal alkynes for the formation of ynones

A highly-efficient and practical method for the formation of ynones from a variety of acyl chlorides and terminal alkynes catalyzed by a nanosized MCM-41 anchored palladium bipyridyl complex is described herein. Aroyl, heteroaroyl, and alkyl acyl chlorides were easily coupled with terminal alkynes, giving good to high isolated yields in the presence of a very low catalyst loading (0.002-0.1 mol % Pd) in Et₃N or diisopropylethylamine at 50 °C. Furthermore, the reaction scale was up to 150 mmol for a single batch reaction, providing the potential for practically synthetic application. After centrifugation, the supported catalyst was able to be recycled and reused several times with only a slight decrease in activity.     

Ru(Ⅱ) Bipyridyl Complex and TiO2 Nanocomposite Based Biomolecule-free Photoelectrochemical Sensor for Highly Selective Determination of Ultra-trace Hg^2+ in Aqueous Systems

A biomolecule-free photoelectrochemical(PEC) probe(denoted as Ru-1) was designed, synthesized and coupled with TiO2 nanoparticles(NPs) for the highly sensitive and selective PEC detection of Hg^2+, a model analyte with hypertoxicity to both human health and ecosystem. The probe Ru-1 was designed with Ru(Ⅱ) bipyridyl complex as the chromophore, thiocyanate ligand as the recognition unit, and carboxylate group as the linkage site to connect Ru-1 to TiO2 nanoparticles. Under irradiation, Ru-1 shows strong affinity to TiO2 and good photophysical properties of strong visible light absorption, slow electron-hole(e-h^+) recombination, and fast photoelectron injection to TiO2 nanoparticles via the bridge of 4-(2,2-bipyridin)-4-yl-thiophene moiety. However, the specific coordination of Hg^2+ with Ru-1 via the thiol moiety in the thiocyanate enlarges the band gap of tlie complex and reduces the photocurrent significantly. The synergistic interaction between TiO2 nanoparticles and the Ru-1 complex led to a selective PEC sensing strategy for Hg^2+ detection. Detectable linear ranges from 10^-12 g/mL to 10^-7 g/mL and from 10^-7g/mL to 10^-3 g/mL were obtained without the interference from possibly co-existed metal ions. The good analytical performances indicate the chemical probe based biomolecule-free PEC platform may offer a new route for the detection of biologically and environmentally important small molecules.     

铼联吡啶系列光敏染料的研究

设计合成了2,2′-联吡啶-4,4′-二羧酸乙酯与过渡金属铼的系列络合物[fac-Re(4,4′-di-COOEt-bpy)(CO)3(Xpy)PF6](其中bpy=2,2′-联吡啶;py=吡啶;X=3-CH3,3-OH,3-NH2和H),对它们的电化学性能、紫外可见吸收、荧光激发和发射光谱进行了研究.结果表明,随着吡啶环上取代基供电子能力的增强,H《CH3《OH《NH2,Re(Ⅱ/Ⅰ)的氧化电位降低,减小了电子回传的驱动力;MLCT最大吸收波长变化不大,最大发射波长略有蓝移,荧光强度减弱,荧光寿命缩短.     

Crystal structure of the hemitoluene solvate of racemiccis-bis(bipyridyl)chloro(tri-n-propylphosphine)ruthenium(II) perchlorate,a species with disordered PPr3 and toluene moieties

The complexcis-[Ru(bpy)₂(PPr₃)Cl⁺][ClO ₄ ^– ] · 0.5 (toluene) crystallizes as a racemate in the monoclinic space group P2₁/n. Both the PPr₃ ligand and the toluene of crystallization are subject to disorder. Ruthenium—ligand distances are: Ru–PPr₃=2.348(2) Å, Ru–Cl=2.426(2) Å and Ru–N(bpy)=2.035(6)–2.112(5) Å.     

Temperature-programmed high performance liquid chromatography separation of mono- and divinyl chlorophyll forms from marine phytoplankton

Summary Divinyl chlorophyll a (a₂) and divinyl chlorophyll b (b₂) are chemotaxonomic marker pigments for the marine prochlorophytes, and can be used to study their distribution in marine samples. In this paper we report a baseline resolution of mono- and divinyl forms of chlorophylls a and b employing polymeric ODS stationary phases at sub-ambient temperatures. The simultaneous resolution of mono- and divinyl forms of chlorophylls a and b, chlorophylls c₁, c₂, c₃, Mg 3,8-divinylphaeoporphyrin a₅ monomethyl ester (MgDVP), and phytol-substituted chlorophylls c was achieved when a temperature step gradient was employed during the analysis. An example is given of the utility of the protocol in oceanic field samples.     

Phototransformation of monovinyl and divinyl protochlorophyllide by NADPH:Protochlorophyllide oxidoreductase of barley expressed in Escherichia coli

The chlorophyll precursors monovinyl protochlorophyllide (MV-PChlide) and divinyl protochlorophyllide (DV-PChlide) were extracted from mutant C-2A' of the unicellular green alga Scenedesmus obliquus which accumulates both protochlorophyllide derivatives in the dark. The two pigments were characterized by absorption and fluorescence spectroscopy and by plasma desorption mass spectrometry. The molecular masses of MV-PChlide and DV-PChlide were determined as 612 and 610 atomic mass units (amu) respectively. Both MV-PChlide and DV-PChlide were accepted as substrates and photoconverted to chlorophyllides in vitro by NADPH:protochlorophyllide oxidoreductase of barley expressed in Escherichia coli.     

A Novel Cu(Ⅱ） Complex with 2,2′-Bipyridyl and L-Methioninate -synthesis,Characterization,Molecular Structure and Stability

The ternary Cu(II) complex with 2,2′‐bipyridyl (bipy) and L‐methioninate (L‐Met) has been synthesized and characterized by elemental analysis, molar conductivity, UV‐Vis spectra, IR spectra and pH‐potentiometric titration methods. The structure of the complex [Cu(L‐Met) (bipy) (H₂O)]ClO₄ · 3/8H₂O was characterized by the X‐ray diffraction analysis. It crystallizes in the triclinic system, space group P1 with four molecules in a unit cell of dimensions, a = 0.7656(2) nm, b = 1.3142(3) nm, c = 2.0596(4) nm, α = 97.70(3)°, β = 97.96(3)°, γ = 94.33(3)°, V= 2.0244(8) nm³, R₁, = 0.0441 and wR₂ = 0.0678. The crystal contains four crystllographically independent [Cu(L‐Met) (bipy) (H₂O)]⁺ complexes (Cu1—Cu4), having a distorted square‐pyramidal geometry with the same coordinated atoms around each copper center. The base plane is occupied by two nitrogen atoms of one bipy, the amino nitrogen atom and one carboxylate oxygen atom from each independent L‐Met moiety, and one water oxygen at an axial position. Cu1 and Cu3 are essentially enantiomers of Cu2 and Cu4. The four molecules are packed with each other by intermolecular hydrogen‐bonding and aromatic‐ring stacking interactions.     

Crystal structure ofcis-[Ru(bpy)2{PPh2(o-tol)}Cl][ClO4]·1.5(CH2Cl2), a structure containing both ordered and disordered dichloromethane molecules of crystallization

The complexcis-[Ru(bpy)₂ {PPh₂(o-tol)}Cl][ClO₄] crystallizes from dichloromethane as the sesqui-dichloromethane solvate. The complex crystallizes in the monoclinic space group P2₁/n with Z=4. The structure was refined toR=5.50% for those 2552 independent reflections with |F ₀|>6(|F ₀|) The octahedral Ru(II) cation is associated with the following bond lengths: Ru-PPh₂(o-tol)=2.360(3)Å. Ru–Cl=2.433(2)Å and Ru–N(bpy)=2.041(8)–2.095(8)Å. Both the perchlorate anion and the dichloromethane molecules of solvation exhibit large amplitudes of vibration. One dichloromethane molecule lies in a general position, the other lies about an inversion center and suffers from disorder.     

Sequential injection analysis (SIA)-chemiluminescence determination of indomethacin using tris[(2,2'-bipyridyl)]ruthenium(III) as reagent and its application to semisolid pharmaceutical dosage forms

Automated sequential injection (SIA) method for chemiluminescence (CL) determination of nonsteroidal anti-inflammatory drug indomethacin (I) was devised. The CL radiation was emitted in the reaction of I (dissolved in aqueous 50% v/v ethanol) with intermediate reagent tris(2,2′-bipyridyl)ruthenium(III) (Ru(bipy)₃³⁺) in the presence of acetate. The Ru(bipy)₃³⁺ was generated on-line in the SIA system by the oxidation of 0.5 mM tris(2,2′-bipyridyl)ruthenium(II) (Ru(bipy)₃²⁺) with Ce(IV) ammonium sulphate in diluted sulphuric acid. The optimum sequence, concentrations, and aspirated volumes of reactant zones were: 15 mM Ce(IV) in 50 mM sulphuric acid 41 μL, 0.5 mM Ru(bipy)₃²⁺ 30 μL, 0.4 M Na acetate 16 μL and I sample 15 μL; the flow rates were 60 μL s⁻¹ for the aspiration into the holding coil and 100 μL s⁻¹ for detection. Calibration curve relating the intensity of CL (peak height of the transient CL signal) to concentration of I was curvilinear (second order polynomial) for 0.1–50 μM I (r = 0.9997; n = 9) with rectilinear section in the range 0.1–10 μM I (r = 0.9995; n = 5). The limit of detection (3σ) was 0.05 μM I. Repeatability of peak heights (R.S.D., n = 10) ranged between 2.4% (0.5 μM I) and 2.0% (7 μM I). Sample throughput was 180 h⁻¹. The method was applied to determination of 1 to 5% of I in semisolid dosage forms (gels and ointments). The results compared well with those of UV spectrophotometric method.