Neuartige massenspektrometrische Zerfallsreaktionen bei α,ω-disubstituierten Alkanen. 15. Mitteilung über das massenspektrometrische verhalten von stickstoffverbindungen [1]

The mass spectral behaviour of α,ω-disubstituted alkanes and, especially, that of different N-substituted α,ω-diaminoalkanes has been investigated. It was found that the two amino groups which are separated by CH₂-groups can fragment only to a small extent indepently from each other. Yet those fragmentation reactions are predominant in which both functional groups participate. The main reactions of this type are:

• 1 Loss of the N-substituent (R) from the molecular ion, leading to the [M⁺—R]-ions.
• 2 Loss of NH₃, primary or secondary amines from the [M⁺—R]-ion in the case of monodi-, tri- and tetra-substituted diamino compounds respectively.
• 3 α-Cleavage to the non charged nitrogen atom by forming the ions
• 4 S_Ni-type fragmentation.

The mechanisms of these fragmentation patterns were deduced by using D-labelled derivatives, from metastabile peaks and high resolution mass spectrometry. These reactions seem to be typical for disubstituted alkanes.     

Some Comments on Fulminic Acid (Knallsäure) and a Praise to Heinrich Wieland and his Work on Organic Derivatives of Nitrogen

The structure, vibrational spectrum, the polymerization and [3+2] cycoaddition reactions of fulminic acid are discussed. In the mass spectra of the solid deposit from gaseous fulminic acid (prepared from sodium fulminate and sulfuric acid) the mass of the adduct of HCNO with hydrogen cyanide was detected, which may be formed by Huisgen 1,3‐dipolar cycloaddition. As examples for Heinrich Wieland's experimental mastership the polymerization and his syntheses of fulminic acid and of explosive dinitrosomethanide [HC(NO)₂]^– are emphasized; the structure of the latter has recently been disclosed by X‐ray structure determination.     

Comparison of Dinitrogen,Methane, Carbon Monoxide,and Carbon Dioxide Mass‐Transport Dynamics in Carbon and Zeolite Molecular Sieves

Equilibrium (based on Henry constants) and kinetic (based on relaxation‐time constants or rather macropore transport diffusivities) selectivities for commercial zeolite and carbon‐molecular‐sieve (CMS) adsorbents were compared. Adsorption isotherms were recorded at ?20°. The frequency‐response (FR) sorption‐rate spectra were determined in the range of ?78 and 70° at 133 Pa. In particles of a larger size than 1.0 mm, macropore diffusion governed the rate of sorption mass transport in both types of microporous materials. The differences in the intercrystalline diffusivities established the kinetic separation of the gases notwithstanding the essential importance of interactions in the micropores. Zeolites seem to be more advantageous for a dynamic separation of CO₂ and CH₄ than CMS 4A. With the CO₂ and CO pair, the CMS is characterized by short characteristic times which, together with a good separation factor, is a double advantage in a short‐cycle adsorption technology. Upon comminution of the carbon pellets, intercrystalline‐diffusion resistance can be completely removed by using CMS 4A adsorbent particles with a diameter smaller than 1 mm. The carbonization of spruce‐wood cubes resulted in an excellent carbon honeycomb structure, which seems to be ideal from a dynamic point of view for applications in short‐cycle adsorption‐separation technologies. In the development of adsorbents, the use of the FR method can be beneficial.     

Detection of layer‐by‐layer self‐assembly multilayer films by low‐temperature plasma mass spectrometry

The detection of layer‐by‐layer self‐assembly multilayer films was carried out using low‐temperature plasma (LTP) mass spectrometry (MS) under ambient conditions. These multilayer films have been prepared on quartz plates through the alternate assembling of oppositely charged 4‐aminothiophenol (4‐ATP) capped Au particles and thioglycolic acid (TGA) capped Ag particles. An LTP probe was used for direct desorption and ionization of chemical components on the films. Without the complicated sample preparation, the structure information of 4‐ATP and TGA on films was studied by LTP‐MS. Characteristic ions of 4‐ATP (M) and TGA (F), including [M]^+?, [M‐NH₂]⁺, [M‐HCN‐H]⁺, and [F + H]⁺, [F‐H]⁺, [F‐OH]⁺, [F‐COOH]⁺ were recorded by LTP‐MS on the films. However, [M‐CS‐H]⁺ and [F‐SH]⁺ could not be observed on the film, which were detected in the neat sample. In addition, the semi‐quantitative analysis of chemical components on monolayer film was carried out, and the amounts of 4‐ATP and TGA on monolayer surface were 45 ng/mm² and 54 ng/mm², respectively. This resulted the ionization efficiencies of 72% for 4‐ATP and 54% for TGA. In order to evaluate the reliability of present LTP‐MS, the correlations between this approach and some traditional methods, such as UV–vis spectroscopy, atomic force microscope and X‐ray photoelectron spectroscopy were studied, which resulted the correlation coefficients of higher than 0.9776. The results indicated that this technique can be used for analyzing the films without any pretreatment, which possesses great potential in the studies of self‐assembly multilayer films. Copyright © 2013 John Wiley & Sons, Ltd.     

The role of the liquid interface agent in mechanical properties improvement of modified chalk filled polyolefins

On the basis of the experimental results described in detail in the following sections an explanation of the mechanism of liquid modifier in chalk filled PP action was proposed. After concluding that liquid modifier does not change the sample morphology and crystallinity it was stated that it facilitates filler particles translocation in polymer matrix during deformation. Such translocations are the necessary condition for saturation of volume increase of the sample due to void formation in the process of polymer filler separation preserving the sample from its premature fracture. The most important physicochemical parameter of liquid modifier seems to be its molecular weight. This parameter determines liquids ability to migrate in micropore structure arising under stress and thus to act as a cracking agent. The possibility of the importance of more efficient heat dissipation in the sample was shown indicating the role of better thermal contacts in the sample in the case of modified chalk used as a filler. Such picture of mechanism of liquid modifier action leads also to two important conclusions:

Due to polymer filler separation by means of liquid layer no further filler particles surface processing, as in some cases, is needed.

The method of modification can be easily generalized for other polymers especially other polyolefins [19], [20] as physicochemical requirements for liquid are known.

     

Nomenclature of Carbohydrates

These Recommendations expand and replace the Tentative Rules for Carbohydrate Nomenclature [1] issued in 1969 jointly by the IUPAC Commission on the Nomenclature of Organic Chemistry and the IUB-IUPAC Commission on Biochemical Nomenclature (CBN) and reprinted in [2]. They also replace other published JCBN Recommendations [3-71 that deal with specialized areas of carbohydrate terminology; however, these documents can be consulted for further examples. of relevance to the field, though not incorporated into the present document, are the following recommendations:

• Nomenclature of cyclitols, 1973 [8]

• Numbering of atoms in myo-inositol, 1988 [9]

• Symbols for specifying the conformation of polysaccharide chains, 1981 [10]

• Nomenclature of glycoproteins, glycopeptides and peptidoglycans, 1985 [11]

• Nomenclature of glycolipids, in preparation [12]

The present Recommendations deal with the acyclic and cyclic forms of monosaccharides and their simple derivatives, as well as with the nomenclature of oligosaccharides and polysaccharides. They are additional to the Definitive Rules for the Nomenclature of Organic Chemistry [13,14] and are intended to govern those aspects of the nomenclature of carbohydrates not covered by those rules.     

Quantum and Classical Molecular Dynamics of Ionic Liquid Electrolytes for Na/Li‐based Batteries: Molecular Origins of the Conductivity Behavior

Compositional effects on the charge‐transport properties of electrolytes for batteries based on room‐temperature ionic liquids (RTILs) are well‐known. However, further understanding is required about the molecular origins of these effects, in particular regarding the replacement of Li by Na. In this work, we investigate the use of RTILs in batteries, by means of both classical molecular dynamics (MD), which provides information about structure and molecular transport, and ab initio molecular dynamics (AIMD), which provides information about structure. The focus has been placed on the effect of adding either Na⁺ or Li⁺ to 1‐methyl‐1‐butyl‐pyrrolidinium [C₄PYR]⁺ bis(trifluoromethanesulfonyl)imide [Tf₂N]^?. Radial distribution functions show excellent agreement between MD and AIMD, which ensures the validity of the force fields used in the MD. This is corroborated by the MD results for the density, the diffusion coefficients, and the total conductivity of the electrolytes, which reproduce remarkably well the experimental observations for all studied Na/Li concentrations. By extracting partial conductivities, it is demonstrated that the main contribution to the conductivity is that of [C₄PYR]⁺ and [Tf₂N]^?. However, addition of Na⁺/Li⁺, although not significant on its own, produces a dramatic decrease in the partial conductivities of the RTIL ions. The origin of this indirect effect can be traced to the modification of the microscopic structure of the liquid as observed from the radial distribution functions, owing to the formation of [Na(Tf₂N)_n]^(n?1)? and [Li(Tf₂N)_n]^(n?1)? clusters at high concentrations. This formation hinders the motion of the large ions, hence reducing the total conductivity. We demonstrate that this clustering effect is common to both Li and Na, showing that both ions behave in a similar manner at a microscopic level in spite of their distinct ionic radii. This is an interesting finding for extending Li‐ion and Li‐air technologies to their potentially cheaper Na‐based counterparts.     

Simple Ligand Effects Switch a Hydrogenase Mimic between H2 and O2 Activation

Herein, we report a [NiRu] biomimetic system for O₂‐tolerant [NiFe]hydrogenases and demonstrate that electron donation to the [NiRu] center can switch the system between the activation of H₂ and O₂ through simple ligand effects by using hexamethylbenzene and pentamethylcyclopentadienyl ligands, respectively. Furthermore, we present the synthesis and direct observations of a [NiRu]–peroxo species, which was formed by the oxygenation of a Ni‐SIa model [NiRu] complex, that we propose as a biomimetic analogue of O₂‐bound species (OBS) of O₂‐tolerant [NiFe]hydrogenases. The [NiRu]–peroxo complex was fully characterized by X‐ray analysis, X‐ray photoelectron spectroscopy (XPS), mass spectrometry, and ¹H NMR spectroscopy. The OBS analogue was capable of oxidizing p‐hydroquinone and sodium borohydride to turn back into the Ni‐SIa model complex.     

Preparation of calix[4]arene-embedded polysulphone membranes,and utilisation of its Cr(VI) transport efficiency

In this study, a tetramine-substituted calix[4]arene derivative, which was synthesised from calix[4]arene by treatment with dimethylamine in one step via Mannich reaction, was used to fabricate a new calix[4]arene-embedded polysulphone membrane (calix@membrane). Its structure and surface morphology were determined using thermogravimetric analysis and scanning electron microscopy, and elemental analysis techniques. Moreover, a Donnan dialysis system was employed to investigate Cr(VI) transport efficacy of calix@membrane at different pH values. Results showed that calix@membrane represented a promising transport capability for HCr₂O₇^? due to their efficient complexation behaviour.     

A mechanism for the loss of 60 u from peptides containing an arginine residue at the C-terminus

The loss of 60 u from protonated peptide ions containing an arginine residue at the C-terminus has been investigated by means of low energy tandem mass spectrometry. The lowest energy conformation of singly charged bradykinin is thought to involve a salt-bridge structure, which may lead to the formation of two isomeric forms. It is thought that one isomer retains the ionizing proton at the C-terminal end of the peptide, leading to the formation of the [b _n?1 + H + OH]⁺ fragment ion, and the other isomer retains the charge at the N-terminus, leading to the formation of the [M + H ? 60]⁺ fragment ion. It was found that the formation of the [M + H ? 60]⁺ ion occurs only from singly charged precursor ions. In addition, the loss of 60 u occurs from peptides in which the charge is localized at the N-terminus. These results indicate that the mechanism of formation of the [M + H ? 60]⁺ ion may be driven by a charge-remote process.     

水热条件下金红石纳米晶在离子液体[C12mim]Cl中的制备

在室温离子液体1-十二烷基-3-甲基氯化咪唑([C12mim]Cl)中,通过水热法制备了具有单晶结构的金红石纳米材料。采用X射线衍射、扫描电镜和透射电镜对样品进行了表征,结果显示所得样品为纯金红石相,形貌呈棒状。扫描电镜和透射电镜图样显示金红石纳米棒的直径约为15 nm,长度在10～100 nm之间。高分辨投射电镜图样显示金红石纳米棒为单晶结构,并沿c轴方向生长。实验结果表明离子液体[C12mim]Cl中的Cl-有利于金红石相生成,[C12mim]+起到了模板剂的作用并提高了金红石纳米棒的结晶度。     

Katalytische Effekte bei den Reaktionen von 2, 4-Dinitrofluorbenzol mit Benzylamin und N-Methylbenzylamin in Benzol. 6. Mitteilung über nucleophile aromatische Substitutionsreaktionen

• (1) The rates of reaction of 2,4-dinitrofluorobenzene with benzylamine and with N-methylbenzylamine have been measured in benzene solution, with and without the addition of pyridine or 1, 4-diaza-bicyclo[2.2.2]octane (DABCO) as catalyst.
• (2) Both reactions are catalyzed by the reacting amine, by pyridine and by 1, 4-diaza-bicyclo[2.2.2]octane.
• (3) Whereas the dependence on base concentration is linear in the case of N-methyl-benzylamine, the rate constants are curvilinearly related to base concentration in the reaction with benzylamine. Steric effects are shown to be responsible for this different behaviour, which is easily understood in terms of the two-step intermediate mechanism (eq.1) for nucleophilic aromatic substitutions.
• (4) Part of the pyridine catalysis has to be attributed to a medium effect, as can be shown directly in the reaction involving benzylamine.
• (5) The sensitivity of both reactions to base catalysis is much greater than that of the reaction of piperidine with 2, 4-dinitrofluorobenzene, but is found to be considerably smaller than in the reaction of p-anisidine with the same substrate, thus suggesting a correlation between the basicity of the reacting amine and the sensitivity of the reaction to base catalysis.

     

Modelling of solid-liquid adsorption: effects of adsorbent heterogeneity

Effects of adsorbent heterogeneity on the adsorption of cobalt phthalocyanine dye on activated carbon have been studied. Adsorption experiments were carried out by varying the temperature and adsorbent mass in batch adsorbers and, in addition, the adsorbent particle size and fluid flow rate in a continuous stirred tank reactor (CSTR)-type adsorber in order to investigate the equilibrium and the kinetics of adsorption.The Brunauer-Emmett-Teller (BET), Langmuir with uniform distribution (LUD) and Langmuir-Freundlich equations are able to represent the equilibrium data with similar accuracy within the range of measurements. Reasonably large values of the heterogeneity parameter (2.69–2.86) show that the carbon surface is energetically heterogeneous.A mathematical model that describes the adsorption dynamics, including film-, pore- and concentration-dependent surface diffusion on an energetically and structurally heterogeneous adsorbent, is presented here and fitted to the experimental concentration vs. time curves obtained in the continuously stirred tank adsorber.Structural heterogeneity of the carbon, if not accounted for in the kinetic model, can be responsible for the very strong concentration dependence of the surface diffusion coefficient and for the variation in the parameter D_o with particle size and adsorber porosity as shown in this work.     

TOF‐SIMS study of cystine and cholesterol stones

Two different human stones, cystine and cholesterol from the kidney and gall bladder, were examined by time‐of‐flight secondary ion mass spectrometry using Ga⁺ primary ions as bombarding particles. The mass spectra of kidney stone were compared with those measured for the standard compounds, cystine and cysteine. Similar spectra were obtained for the stone and cystine. The most important identification was based on the existence of the protonated molecules [M + H]⁺ and deprotonated molecules [M‐H]^‐. The presence of cystine salt was also revealed in the stone through the sodiated cystine [M + Na]⁺ and the associated fragments, which might be due to the patient treatment history. In the gallstone, the deprotonated molecules [M‐H]⁺ of cholesterol along with relatively intense characteristic fragments [M‐OH]⁺ were detected. Copyright © 2012 John Wiley & Sons, Ltd.     

11-Amino-5H-dibenzo[b,e]-1, 4-diazepine. 10. Mitteilung über siebengliedrige Heterocyclen

11-Amino-5H-dibenzo[b,e]-1, 4-diazepines V, several of which possess neuroleptic properties, have been prepared using three methods:

• 1 Aminolysis of either iminothioethers IV (X = methyl or an activating group such as cyanomethyl and p-nitrobenzyl) or the iminochlorides III.
• 2 Bischler-Napieralski type cyclodehydration of o-anilinophenyl-ureas IX (only applicable for the synthesis of compounds V where R is other than hydrogen).
• 3 Cyclodehydration of amino-amides VII by various condensing agents.

     

Synthesis,Structure, and Redox Chemistry of a Vitamin-B12s-Related Macrocyclic Complex of Cobalt(I)

(±)-[1-hydro-8H-HDP]cobalt(I) 1

1 Full name of 1: [2,2,3,3,7,7,8,8,12,12,13,13,17,17,18,18,-hexadecamethyl-2,3,7,8,12,13,17,18,-octahydro-1H,23H-10,20-diaza-porphinato]cobalt(I); full name of 2a : dibromo[2,2,3,3,7,7,8,8,12,12,13,13,17,17,18,18-hexadecamethyl-2,3,7,8,12,13,17,18-octahydro-1H,21H-10,20-diazaporphinato]cobalt(III).

2 For the nomenclature of [HDP]-complexes see addendum in [2].

is obtained by chemical or electrochemical four-electron reduction of (±)-dibromo- or (±)-dicano[1-hydroxy-8H-HDP]cobalt(III) 2a or 2b ⁴, respectively. The crystal nad molecular structure of 1 was determined by combination of X-ray analysis and MS, ¹H-, and ¹³C-NMR spectroscopy. Square-planar coordinated Co(I) lies closely to the best plane through the four N-atoms which form the first coordination sphere. Thermodynamic data for the coordination of axial bases with the cation of [1-hydroxy-8H-HDP]cobalt 2 in its different metal oxidation states were determined. The pathway of the overall four-electron reduction of 2a to 1 was elucidated: it involves a two-electron reduction of the central metal, a two-electron reduction of the macrocycle accompanied by elimination of the OH-group and final protonation at C(1). Evidence for an intramolecular electron transfer between the central metal and the macrocycle is presented.     

Metallo‐supramolecular block copolymer micelles: Improved preparation and characterization

Micelles prepared from amphiphilic block copolymers in which a poly(styrene) segment is connected to a poly(ethylene oxide) block via a bis‐(2,2′:6′,2″‐terpyridine‐ruthenium) complex have been intensely studied. In most cases, the micelle populations were found to be strongly heterogeneous in size because of massive micelle/micelle aggregation. In the study reported in this article we tried to improve the homogeneity of the micelle population. The variant preparation procedure developed, which is described here, was used to prepare two “protomer”‐type micelles: PS₂₀‐[Ru]‐PEO₇₀ and PS₂₀‐[Ru]‐PEO₃₇₅. The dropwise addition of water to a solution of the compounds in dimethylformamide was replaced by the controlled addition of water by a syringe pump. The resulting micelles were characterized by sedimentation velocity and sedimentation equilibrium analyses in an analytical ultracentrifuge and by transmission electron microscopy of negatively stained samples. Sedimentation analysis showed virtually unimodal size distributions, in contrast to the findings on micelles prepared previously. PS₂₀‐[Ru]‐PEO₇₀ micelles were found to have an average molar mass of 318,000 g/mol (corresponding to 53 protomers per micelle, which is distinctly less than after micelle preparation by the standard method) and an average hydrodynamic diameter (d_h) of 18 nm. For PS₂₀‐[Ru]‐PEO₃₇₅ micelles, the corresponding values were M = 603,000 g/mol (31 protomers per micelle) and d_h = 34 nm. The latter particles were found to be identical to the “equilibrium” micelles prepared in pure water. Both micelle types had a very narrow molar mass distribution but a much broader distribution of s values and thus of hydrodynamic diameters. This indicates a conformational heterogeneity that is stable on the time scale of sedimentation velocity analysis. The findings from electron microscopy were in disagreement with those from the sedimentation analysis both in average micelle diameter and in the width of the distributions, apparently because of imperfections in the staining procedure. The preparation procedure described also may be useful in micelle formation from other types of protomers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4458–4465, 2004     

Rein- und MischphasenPigmente mit Klinopyroxenstruktur

Pure and Mixed-phase Pigments with Clinopyroxene Structure

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Structure and further fragmentation of significant [a3 + Na − H]+ ions from sodium‐cationized peptides

A good understanding of gas‐phase fragmentation chemistry of peptides is important for accurate protein identification. Additional product ions obtained by sodiated peptides can provide useful sequence information supplementary to protonated peptides and improve protein identification. In this work, we first demonstrate that the sodiated a₃ ions are abundant in the tandem mass spectra of sodium‐cationized peptides although observations of a₃ ions have rarely been reported in protonated peptides. Quantum chemical calculations combined with tandem mass spectrometry are used to investigate this phenomenon by using a model tetrapeptide GGAG. Our results reveal that the most stable [a₃ + Na ? H]⁺ ion is present as a bidentate linear structure in which the sodium cation coordinates to the two backbone carbonyl oxygen atoms. Due to structural inflexibility, further fragmentation of the [a₃ + Na ? H]⁺ ion needs to overcome several relatively high energetic barriers to form [b₂ + Na ? H]⁺ ion with a diketopiperazine structure. As a result, low abundance of [b₂ + Na ? H]⁺ ion is detected at relatively high collision energy. In addition, our computational data also indicate that the common oxazolone pathway to generate [b₂ + Na ? H]⁺ from the [a₃ + Na ? H]⁺ ion is unlikely. The present work provides a mechanistic insight into how a sodium ion affects the fragmentation behaviors of peptides. Copyright © 2015 John Wiley & Sons, Ltd.     

Effect of adsorbate properties on adsorption mechanisms: computational study

The paper presents results of research on identification of localized and mobile adsorption mechanisms of several selected adsorbates, on geometrically heterogeneous graphite-like carbonaceous surface. The proposed approach is intended to examine effects of surface geometrical heterogeneity on shape and volume of space occupied by the selected adsorbate molecules. In particular, the continuously moving individual molecule mass center properties, near adsorbent surface are investigated. When compared to the corresponding liquid phase properties it enables to outline the conditions for localized and mobile adsorption mechanisms. To this aim, the kinematic and thermodynamic equilibrium conditions are taken under the study, providing information on particular mechanism predomination. Therefore, the approach gives a cognitive basis for selection of the most appropriate mathematical adsorption model to reliable examination of material porous structure (comprising similar geometrical heterogeneity). Numerous simulation results for selected adsorbates H₂, CO₂, CH₃OH and C₆H₆ are presented, and adsorption mechanism identification is discussed.