2,6-Di-tert-butylphenols and phenoxyl radicals with metal—metal bonds

-Aryl trans-bistriphenylphosphine complexes based on 2,6-di-tert-butylphenol containing Pt—SnCl₃, Pt—GeCl₃ groups were synthesized. Oxidation of these compounds gives the corresponding phenoxyl radicals, which were studied by ESR spectroscopy. The transformation of the diamagnetic complexes to the paramagnetic state is accompanied by cleavage of the Pt—Sn, Pt—Ge bonds and by elimination of SnCl₂, GeCl₂.     

Preparation of Zeolite—metal Composite Membrane

A NaA Zeolite membrane was synthesized on the surface of the stainless steel slab. The membrane was characterized by XRD and SEM. The membrane was continuous and highly intergrown. The size of NaA zeolite crystals was about 5-6μm.     

Nanoporous carbon — metal composites for hydrogen storage

Metal-carbon composites have shown considerable hydrogen storage potential at room temperature. In the present work the behaviour of two different Pd amalgam doped carbon substrates, namely a carbogenic foam and a mildly oxidised ordered mesoporous carbon, are compared on the basis of their hydrogen sorption properties at 77 and 298 K and low pressures, aiming to investigate the effect of surface on the storage capacity. In both cases, the introduction of alloy nanoparticles leads to an improvement of the hydrogen uptake with respect to pure carbons. This effect is significant for the carbogenic foam however small for the ordered carbon.      

IMAC—Immobilized metal ion affinity based chromatography

Immobilized metal ion affinity chromatography (IMAC) is a highly versatile separation method based on interfacial interactions between biopolymers in solution and metal ions fixed to a solid support, which is usually a hydrophilic cross-linked polymer.Polymer-fixed Zn(II), Ni(II), Co(II) and Cu(II) are particularly well suited for fractionation of proteins primarily on the basis of their relative content of surface-located imidazole residues but also of Trp and Cys residues as well as terminal amino groups.IMA methods can also be devised for purification of phosphoproteins and calcium-binding proteins. In some instances, the performance of IMA gels is comparable to that of biospecific affinity-based adsorbents. In fact IMA gels may, by sandwich techniques, occasionally be converted to biospecific adsorbents.Selectivity can be varied by choice of type of ligand and metal ion as well as by varying the modes of elution, including affinity desorption.     

Thermal behavior of metal carboxylates—II. Lead formate

Experimental data obtained by i.r. emission spectrometry indicate that the thermal behavior of lead formate is complex. By heating in air, after a phase transition at 115°C, decomposition takes place which may lead directly to metal and oxide or to carbonate, to a basic carbonate and finally to oxide. Under vacuum the same transformations occur at higher temperatures and lead to metal.     

Photoacoustic spectra of some biologically active metal chelates—II

The visible absorption spectra of 5-(p-sulphon atophenyl)-1,3,4-oxadiazole-2-thione (ligand) and the metal chelates derived from Mn(II), Co(II), Ni(II) and Zn(II) salts have been recorded, in the powder form, on a single beam photoacoustic spectrometer. The photoacoustic spectra give information about charge transfer and d-d transitions that could not be observed in their optical u.v.-vis spectra.     

The internal metal—oxygen stretching frequency in ordered perovskites

The stretching vibrations of the B′O₆ octahedron in ordered perovskites A₂BB′O₆ are compared and discussed.     

Redox-active metal–metal bonds between lanthanides in dimetallofullerenes

1. Download : Download high-res image (118KB)
2. Download : Download full-size image

     

Reactivity of transition metal fluorides—IX Protactinium pentafluoride and tetrafluoride

In a continuing survey of the relative reactivities of higher fluorides of d- and ƒ-transition elements, redox reactions of protactinium pentafluoride with selected reductants have been studied. Halogen-exchange reactions with covalent chlorides have been investigated for both the pentafluoride and tetrafluoride. The results of these reactions are correlated with those from previous investigations. Special attention was given to preparative and reaction techniques because of the radioactive nature and because of the small quantities of the compounds available for this work compared with the scale of earlier related studies in this series.     

Synthesis of macrocycles containing tetrazole units—potential metal complexation sites

The ability of ligands to bind different metal ions is the basis for the design of dinucleating or polynucleating ligands. Indeed, macrocyclic and macroacyclic compounds have attracted much attention in recent years due to their role in understanding molecular processes that occur in biochemistry, catalysis and material science. For example, much effort has been expended on the construction of coordination polymers and on complexes with double or triple helicate structures. In this review, our recent studies into macrocycles containing tetrazole functional groups are summarised.     

Pd-modified PEDOT layers obtained through electroless metal deposition—electrooxidation of glycerol

Pd-poly(3,4-ethylenedioxythiophene) (PEDOT)-based electrocatalytic materials are obtained by coupling Pd ion reduction with oxidation of pre-reduced PEDOT coatings. Electroless metal deposition is carried out in single or triple electroless deposition steps resulting in Pd NPs with mean size ranging between 12 and 22 nm, respectively. The proposed method of dispersing the Pd catalytic phase provides the opportunity to obtain high electrocatalytic currents with Pd loadings as low as 10 μg cm^?2. The Pd-PEDOT catalyst obtained by triple-step metal deposition shows stable voltammetric behavior with respect to glycerol oxidation in alkaline solution. The established mass activity is between the highest values achieved at Pd-electrocatalysts without involving additional electrocatalytic materials or special supports.     

MeCAT—new iodoacetamide reagents for metal labeling of proteins and peptides

Besides protein identification via mass spectrometric methods, protein and peptide quantification has become more and more important in order to tackle biological questions. Methods like differential gel electrophoresis or enzyme-linked immunosorbent assays have been used to assess protein concentrations, while stable isotope labeling methods are also well established in quantitative proteomics. Recently, we developed metal-coded affinity tagging (MeCAT) as an alternative for accurate and sensitive quantification of peptides and proteins. In addition to absolute quantification via inductively coupled plasma mass spectrometry, MeCAT also enables sequence analysis via electrospray ionization tandem mass spectrometry. In the current study, we developed a new labeling approach utilizing an iodoacetamide MeCAT reagent (MeCAT-IA). The MeCAT-IA approach shows distinct advantages over the previously used MeCAT with maleinimide reactivity such as higher labeling efficiency and the lack of diastereomer formation during labeling. Here, we present a careful characterization of this new method focusing on the labeling process, which yields complete tagging with an excess of reagent of 1.6 to 1, less complex chromatographic behavior, and fragmentation characteristics of the tagged peptides using the iodoacetamide MeCAT reagent.     

MS／MS Study of Deoxydinucleotides Bound with Alkali—metal Ions Using ESI—MS

Positive ion ESI-MS has been used to examine the fragmentation pathways of the complex ions of deoxydinucleotides with H^ ,Na^ ,K^ by LCQ instrument.It had been found that the dissociation Varied markedly due to the differences of the base sequence.The alkali-metal ion binding site and the charcaterization of dissociation were directed by the size of metal ion,the sequesce of base and the steric hindrance.     

The effect of metal optical constants on far- and mid-infrared reflection—absorption

Although mid-infrared reflection—absorption spectroscopy is almost routine in some laboratories, the application of this technique to far-infrared spectroscopy is generally acknowledged as a difficult experiment at best. In this report the effect of increasing optical indices with wavelength for metals is demonstrated to be a root cause of this difficulty. When appropriate, iron is a reasonable substrate because of the comparatively small imaginary component of its refractive index in the far-infrared region. In addition, there is only a modest loss in spectral intensity of the spectrum for a film on iron relative to the use of the more noble metals as substrate.     

Loosely coordinating diluted highly concentrated electrolyte toward —60℃ Li metal batteries

Lithium metal batteries(LMBs) promise energy density over 400 Wh kg^-1.However,they suffer severe electrochemical performance deterioration at sub-zero temperatures.Such failure behavior highly correlates to inferior lithium metal anode(LMA) compatibility and sluggish Li⁺ desolvation.Here,we demonstrate that cyclopentylmethyl ether(CPME) based diluted high-concentration electrolyte(DHCE)enables-60℃ LMBs operation.By leveraging the loose coordination between Li⁺ an...     

DFT study of chemical mechanism of pre-SERS spectra in Pyrazine–metal complex and metal–Pyrazine–metal junction

The chemical mechanism of Normal Raman Scattering (NRS) and pre-surface enhanced Raman scattering (pre-SERS) spectra for Pyrazine–Ag₂ complex, Ag₂–Pyrazine–Ag₂ junction and Ag₂–Pyrazine–Au₂ junction were investigated with density functional theory (DFT) and charge difference densities (CDDs) for the first time. The NRS intensities of the above three structures enhanced obviously relative to isolated Pyrazine and the enhancement mechanism was confirmed to be static chemical enhancement. The pre-SERS intensities of the above three structures enhanced evidently compared to corresponding NRS intensities, and the enhancement mechanism was confirmed to charge transfer (CT) resonance Raman enhancement. The largest enhanced orders of NRS and pre-SERS intensities among the three structures were up to 10³ and 10⁵, respectively. Compared the intensity of pre-SERS with corresponding intensity of NRS spectra, the enhancement effect of Pyrazine–Ag₂ complex was larger than the others. Intramolecular and intermolecular CT on resonant electronic transition were described by CDDs.