Electrospray ionization mass spectrometric analysis of highly reactive glycosyl halides

Highly reactive glycosyl chlorides and bromides have been analysed by a routine mass spectrometric method using electrospray ionization and lithium salt adduct-forming agents in anhydrous acetonitrile solution, providing salient lithiated molecular ions [M+Li]?, [2M+Li]? etc. The role of other adduct-forming salts has also been evaluated. The lithium salt method is useful for accurate mass determination of these highly sensitive compounds.     

Thermodynamics of micelle formation of the counterion coupled gemini surfactant Bis(4-(2-dodecyl)benzenesulfonate)-Jeffamine salt and its dynamic adsorption on sandstone

A novel counterion-coupled gemini (cocogem) surfactant, DBSJ, was synthetized via the 2:1 coupling reaction between 4-(2-dodecyl)benzenesulfonic acid (Lutensit A-LBS) and polypropyleneglycol-bis(2-aminopropyl) ether (Jeffamine D230). The surfactant had a polydispersity index of Mw/Mn = 1.04, as determined by electrospray-ionization mass spectrometry. The micellar properties of DBSJ in water were investigated in the temperature range 283-348 K by conductometry and titration microcalorimetry. The critical micelle concentration (cmc) of the cocogem was found to be more than 1 order of magnitude less than that of monomeric sodium 4-(2-dodecyl)benzenesulfonate (SDBS). The mean degree of dissociation in the temperature range studied proved to be alpha = 0.39. The calorimetric enthalpies of micelle formation agreed well with the enthalpies calculated via the van't Hoff relation. The cmc versus T curve passes through a minimum just below room temperature, after which the micelle formation changes from endothermic to exothermic. The Gibbs free energy of micelle formation was nearly constant as the temperature was increased, due to enthalpy/entropy compensation. The isotherm for DBSJ adsorption from aqueous solution onto sandstone was determined by continuous flow frontal analysis solid/liquid chromatography at 298 K and 60 bar. The adsorption of DBSJ on sandstone followed an S-type isotherm. Surface aggregation occurred over an extended range of concentration. Surface saturation was reached at a solution concentration more than 1 order of magnitude less than for monomeric SDBS. This finding is a point of concern in the chemical flooding of oil reservoir rocks to enhance oil recovery.     

Isomeric ent‐Labdane‐Type Diterpenoids from the Stems of Rhizophora mucronata

Two new constitutional isomers of ent‐labdane‐type diterpenoids, 1 and 2 , with an unusual seven‐membered lactone moiety (i.e., 1 ), together with two known compounds, 3 and 4 , were isolated from the acetone extract of Rhizophora mucronata. Their structures were elucidated as rhizomucronol A and B ( 1 and 2 , resp.) by spectroscopic analyses and chemical evidence. The absolute configuration of 2 was established by applying the Mosher ester procedure.     

A Novel Reaction between the P=O Group of Cyclic 2,4,6-Trialkylphenylphosphine Oxides and Dimethyl Acetylenedicarboxylate (DMAD)

The reaction of cyclic P-aryl phosphine oxides with DMAD affords ylides/phosphoranes via oxaphosphetes.     

Combined X‐ray microanalytical study of the Nd uptake capability of argillaceous rocks

Argillaceous rocks are considered as suitable host rock formation to isolate the high‐level radioactive waste from the biosphere for thousands of years. Boda Claystone Formation, the possible host rock formation for the Hungarian high‐level radioactive waste repository, has geologically and mineralogically been studied in detail, but its physico‐chemical parameters describing the retention capability of the rock needed further examinations. Studies were performed on thin sections subjected to 72 h sorption experiments using inactive Nd(III). Nd(III) has been used as a chemical analogue for transuranium elements of the radioactive waste to examine the ion uptake capability of the micrometre size mineral phases occurring in the rock. The elemental mapping of synchrotron radiation‐based microscopic X‐ray fluorescence (micro‐XRF) combined with scanning electron microscopy energy dispersive X‐ray analysis (SEM/EDX) has sufficient sensitivity to study the uptake capability of the different mineral phases on the microscale without the necessity of applying radioactive substances. Elemental maps were recorded on several thousand pixels using micrometre magnitude spatial resolution. By interleaving micro‐XRF and SEM/EDX data sets from the same sample area and applying multivariate methods, calcite and clay minerals could be identified as the main mineral phases responsible for Nd(III) uptake without using additional microscopic X‐ray diffraction mapping. It should be highlighted that the ion uptake capability of dolomite containing calcium and magnesium could be distinguished from the characteristics of calcite only by the interleaving of micro‐XRF and SEM/EDX data sets. The presence of minerals was verified by applying microscopic X‐ray diffraction point measurements. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis and complexation of novel dibenzo[<Emphasis Type="Italic">c.e</Emphasis>][1,2]oxaphosphorine-based P-ligands

The reaction of chloro-dibenzo[c.e][1,2]-oxaphosphorine with (L)-methyl prolinate gave the corresponding phosphorous ester-amide, while the interaction of the same starting material with half an equivalent of 2-methylaminothanol and (1S,2R)-(+)-ephedrine led to the corresponding bis(dibenzooxaphosphorine) derivatives that are bidentate P-ligands. The new P-ligands prepared were characterized as the corresponding P-borane and P-oxide derivatives. The P-ligands were utilized in the synthesis of novel Pt-complexes, which gave a species of PtCl₂P₂ type, while two others were seven-membered chelate ring complexes. Structures of the Pt-complexes were elucidated on the basis of stereospecific J _Pt–P couplings and quantum chemical calculations.     

New advances in digital image processing

Enhancement of noisy image data is a very challenging issue in many research and application areas. In the last few years, non-linear filters, feature extraction, high dynamic range imaging methods based on soft computing models have been shown to be very effective in removing noise without destroying the useful information contained in the image data. In this paper new image processing techniques are introduced in the above mentioned fields, thus contributing to the variety of advantageous possibilities to be applied. The main intentions of the presented algorithms are (1) to improve the quality of the image from the point of view of the aim of the processing, (2) to support the performance, and parallel with it (3) to decrease the complexity of further processing using the results of the image processing phase.     

Matrix/analyte ratio influencing polymer molecular weight distribution in matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry

Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF‐MS) has been used to characterize poly(L‐lysine) polymers and unique oligomer peptides, like 10‐, 15‐ and 25‐mer [Lys]_n oligolysine peptides. Several matrices have been tried in order to find optimal conditions, but only α‐cyano‐4‐hydroxycinnamic acid gave analytically useful spectra. The synthetic oligomers and their mixtures gave good quality spectra, showing protonated and cationized molecules, including doubly charged species. The polymers, analogously, gave a wide distribution of single‐ and double‐cationized peak series. The polymer distributions observed indicate the presence of significant suppression effects. The concentration (matrix/analyte ratio) was found to influence the results significantly; distributions shifting to higher masses when higher polymer concentrations were used. This effect was studied in detail using the synthetic (‘monodisperse’) oligolysine peptides. It was found that the relative intensities change by over an order of magnitude in the 0.1–10 pmol/µL concentration range (typical for most proteomic analyses). The results indicate that concentration effects need to be considered when MALDI‐MS is used for quantitative purposes. Copyright © 2009 John Wiley & Sons, Ltd.     

Preparation, Crystal Structure and Spectroscopic Properties of Dimeric [Zn(2-bromobenzoato)2(phenazone)]2 and Monomeric [Zn(2-bromobenzoato)2(thiourea)2]·2H2O

Abstract  

The binuclear zinc complex bis(2-bromobenzoato-O)-bis(μ ₂ -2-bromobenzoato-O,O′)-bis(phenazone-O)-dizinc(II) (I) and the mononuclear dihydrate bis(2-bromobenzoato-O)-bis(thiourea-S)-zinc(II) (II) have been synthesized and characterized by means of elemental analysis and spectroscopic methods (IR, ¹H and ¹³C NMR, EDS). The solid state structures of both compounds were determined by single-crystal X-ray diffractometry. Compound [Zn(2-BrC₆H₄COO)₂(phen)]₂ (phen—phenazone) (I) crystallized as a dimeric compound with a triclinic lattice (space group P − 1), where both zinc atoms, interconnected by two carboxylate groups, possess a distorted tetrahedral coordination environment. The crystallographic data of complex I: a = 9.9410(3) ?, b = 10.7309(3) ?, c = 12.9237(4) ?, α = 93.6004(17)°, β = 92.5898(11)°, γ = 116.2192(16)°, V = 1230.26(6) ?³, Z = 1. Complex [Zn(2-BrC₆H₄COO)₂(tu)₂]·2H₂O (tu—thiourea) (II) crystallized with an orthorhombic lattice (space group Aba2) as a monomeric compound, where the coordination environment of the central zinc atom is a distorted tetrahedron. The crystallographic data of complex II are: a = 9.8595(3) ?, b = 19.7052(5) ?, c = 12.5908(3) ?, V = 2446.18(11) ?³, Z = 4. The modes of the carboxylate binding were assigned from the IR spectra using the magnitude of the separation between the carboxylate stretches (Δ), which correlated well with the crystal structures. The computed theoretical IR spectrum agreed well with the experimental data.