Influence of conjugated nitrogenous bases on the spectra and structure of mixed-ligand nickel(II) chelates containing β-diones

The infrared and electronic excitation spectra of a series of new nickel(II) chelates containing an-diimine (or nitrogenous base, enR) and the anion of a-dione (1,3-ketoenol or 1,3-ketoester,H) were obtained in the solid state and in solution. The composition and the overall structure of the new chelates in the solid state depends on ligand concentration, the substituents within the-dionato moiety and the counterion present. The IR and electronic excitation spectra of [Ni(enR)₂ ]NO₃ and [Ni(enR)(O₂NO)] indicate, in conjunction with other physicochemical measurements, bidentate coordination of the ligands, while the spectral shifts reveal replacement of the (O,O)nitrato group by basic solvents. The existence of the nickel(II) in an octahedral environment is confirmed by an X-ray structure analysis of [Ni(dpamH)₂acac]NO₃ · CH₃OH (monoclinic, space groupP2_l/n, a=17.296(1),b=7.462(1),c=21.604(3) å,=95.65(1),Z=4, R=0.0534,Rw=0.0600), where dpamH denotes the 2,2-dipyridylamine.     

Crystal Structure of (6S,9S,13R,14S)-7,8-Didehydro-3,7-dimethoxy-17-methylmorphinan-4,6-diol

1 INTRODUCTION (9S,13R,14S)-7,8-Didehydro-3,7-dimethoxy-4-hydroxy-17-methylmorphinan-6-one I is an impor- tant natural product that was used to ease pain, decrease blood pressure and diminish inflammation. In order to study the stereochemistry of the reduction of I with potassium boronhydride, the crystal structure of the title compound II was determined by X-ray diffraction method. 2 EXPERIMENTAL 2. 1 Instrument The melting point was measured on a Yanagimoto MP-500 apparatus…     

Preparation and reactivity of metal-containing monomers

Mono- and disubstituted cluster metal-containing monomers were obtained under mild conditions on interaction of Rh₆(CO)₁₆ with 4-vinylpyridine (4-ViPy) in the presence of N-trimethylaminoxide. These products were characterized by IR and¹H NMR spectroscopy and by elemental and X-ray analyses. Rh₆(CO)₁₅(4-ViPy) was found to be an octahedral cluster with eleven terminal and four ₃-bridging carbonyl ligands. 4-ViPy is linked with the Rh(3) atom through the N atom and occupies the coordination site of the twelfth CO terminal ligand. The mean value of the Rh-Rh bond length is 2.762 Å. The unsaturated ligand has little or no effect on the geometry of the starting cluster and its double bond retains the ability to undergo addition reactions.For part 28, seeRuss. Chem. Bull., 1993, 453.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 975–979, May, 1993.     

膦、胂叶立德的化学与应用——Ⅰ.用红外光谱对膦、胂叶立德结构的研究

以78个带吸电子取代基的膦、胂叶立德的红外光谱的解析为根据,讨论了它们的结构及其与光谱的关系。     

双取代单酰胺与硝酸铀酰萃合物的制备与表征

合成了系列双取代单酰胺萃取剂，利用萃取方法获得了与硝酸铀酰的萃合物。利用元素分析、红外光谱、¹H NMR和¹³C NMR对萃合物进行了表征。结合实验数据初步探讨了萃合物的结构、萃取剂的结构与性能以及萃取体系的三相等问题。     

Direct targeting of human plasma for matrix-assisted laser desorption/ionization and analysis of plasma proteins by time of flight-mass spectrometry

A method to analyze human plasma proteins without fractionation, directly applying a plasma-matrix mixture on the target plate of a matrix-assisted laser desorption/ionization-time of flight-mass spectrometer (MALDI-TOF-MS), has been described. Peaks of ionized plasma proteins could not be detected applying a mixture of an undiluted plasma sample and a matrix solution, but they appeared when the plasma was diluted before mixing with the matrix. Tenfold diluted plasma provided well-resolved protein peaks in the m/z range from 4000 to 30,000. The addition of a simple post-crystallization washing procedure performed on the target plate further improved the quality of mass spectra. We numbered 58 peaks in the range of 4-160 kDa and 32 out of which were assigned to the plasma protein species which have been reported. Especially high sensitivity and resolution were obtained in the region < 30 kDa, where multiple isoforms of apolipoprotein A-I, apolipoprotein A-II, apolipoprotein C-I, apolipoprotein C-II, apolipoprotein C-III, and transthyretin could be assigned. Various post-translational modifications are involved in the isoforms, e.g., proteolytic cleavage, glycosylation and chemical modifications. This method will become complementary with the present electrophoretic techniques, especially for the analysis of low-molecular-mass proteins.     

Quantitation in capillary electrophoresis-mass spectrometry

CE-MS has evolved into a strong alternative to LC-MS. Most of CE-MS applications deal with characterization and identification. However, quantitative aspects have gained importance in, e.g., pharmaceutical and biotechnological applications. Here we summarize and evaluate various methodological aspects in order to achieve sensitive and reproducible results. Similar to LC-MS, aspects of matrix influence on the electrospray process need to be carefully addressed when quantitative results are intended by CE-MS. Due to a more complicated coupling special emphasis needs to be put on the CE-MS interface. Generally linearity over more than three orders of magnitude can be achieved by CE-ESI-MS. Furthermore, a literature survey has been performed in order to give an overview over quantitative measurements performed by CE-MS. The precision can be doubled when changing from a structural related to an isotopically labeled internal standard. Thus a level of precision better than 5% RSD can be achieved.