Jan F. Biernat

Utilization of standards generated in the process of thermal decomposition chemically modified silica gel for a single point calibration of a GC/FID system

The utilization of a multicomponent gaseous standard mixture, containing CO and CO(2) and obtained by thermal decomposition of a so-called immobilized compound, for a single point calibration of a GC/FID system are described. The generation of such a mixture takes place as a result of thermal decomposition of a sample of chemically modified silica gel placed in a heated chamber of thermal desorber coupled with the device being calibrated via a catalytic methanizer. The mean amount of the analyte librated from unit mass of the gel was 0.71 mg g(-1) (RSD = 3%) for carbon monoxide and 0.86 mg g(-1) (RSD = 3%) for carbon dioxide.

Cyclopentadienyl-ruthenium complexes : I. The reactivity of some π-cyclopentadienyl-bistriphenylphosphine-ruthenium(II) complexes

Abstract Several ruthenium complexes of the CpRuX(PPh3)2 type, where X = Cl, Br, I, NCS, NCO, CN, BH4, H, D, and some of the CpRuS2CZ(PPh3) type, where Z = NR2 or OR, were obtained. The hydride CpRuH(PPh3)2 was obtained in high yield by reaction of CpRuCl(PPh3)2 with ROM (R = alkyl, M = alkali metal). The other complexes were obtained by ligand exchange of the chloride or hydride with MX salts or HX acids, respectively. Reaction of chloride or hydride with cyclopentadiene led to ruthenocene. However, when pyrrole was used instead of cyclopentadiene, it was not possible to obtain azaruthenocene in this way.

Hybrid biobattery based on arylated carbon nanotubes and laccase.

Single-walled carbon nanotubes (SWCNT) were covalently modified with anthracene and anthraquinone and used for the construction of cathodes for biocatalytic reduction of dioxygen. The nanotubes with aromatic groups casted onto the electrode increased the working surface of the electrode and enabled efficient direct electron transfer (DET) between the enzyme and the electrode. The aryl groups enter the hydrophobic pocket of the T1 center of laccase responsible for exchanging electrons with the substrate. Glassy carbon electrode covered with arylated SWCNT and coated with a layer of neutralized Nafion containing laccase was found to be a very efficient cathode in the hybrid battery. Zn wire covered with a Nafion film served as the anode. The cell parameters were determined: power density was 2 mW/cm(2) and the open circuit potential was 1.5 V.

Synthesis, x-ray structure and electrochemical properties of a new crown ether with a cis azo unit in the macrocycle

Abstract A chromogenic 13-membered crown ether with a cis azo unit in the macrocycle has been obtained as a side product during the reduction of 1,5-bis (2′-nitrophenoxy)-3-oxapentane. The electrochemical properties of this compound have been studied by the voltammetric method. Its behaviour as an ionophore in ion-selective membrane electrodes has also been investigated. The X-ray structures of the new crown ether 3 and the parent compound 1 have been determined.

Complexing and Chelating Agents Immobilized on Silica Gel and Related Materials and Their Application for Sorption of Inorganic Species

Abstract Solid materials bearing bonded organic functional groups are reviewed. The properties of the oxide supporting materials, silica gel in particular, their chemical and physical properties and the nature of the surface residues are part of this review. Processes leading to modification of the silica gel surface with mono- and polylayers of other oxides resulting in materials with modified properties as well as their susceptibility to chemical modification are also presented. Data on silanization procedures to bond supporting materials with commercial or synthesized organosilicon compounds have been carefully collected and discussed. Special emphasis has been paid to reactions which change the chemical nature of the bonded organic residues leading to valuable materials for partition, ion, ion-exchange, and affinity chromatography as well as for specific separation methods. Data on the collection, separation and preconcentration of inorganic species using these materials are an important part of this ...

GENERATION OF STANDARD GASEOUS MIXTURES BY THERMAL DECOMPOSITION OF SURFACE COMPOUNDS : STANDARD MIXTURES OF THIOLS

Abstract A new concept has been introduced for the generation of standard gaseous mixtures which is based on the thermal decomposition of surface-bonded residues and leads to the production of a single volatile product. An example is demonstrated which makes use of the ease with which silica gel-anchored dithiocarbamate groups decompose to form thiols.

13-Membered crown ethers with azo or azoxy unit in the macrocycle - synthesis, membrane electrodes, voltammetry and Langmuir monolayers

Abstract A facile way to obtain substituted azo- and azoxycrown ethers has been developed. Applicability of these crown ethers in sodium-sensitive membrane electrodes has been studied. Voltammetric behavior of the crown ethers bearing azo- and azoxy- subunits in the macrocyclic system has been characterized. Formation of Langmuir-Blodgett monolayers of amphiphilic azocrown ethers on aqueous subphase has been investigated.

Macrocyclic polyfunctional lewis bases. VII. Size and structure controlled stabilities of polyaza-crown ether complexes with Co2+−Zn2+ ions

Stability constants have been determined at 25 °C in aqueous 0.1 M Et4NClO4 medium by potentiometric method of the following ligands: 1,7-dioxa-4,10-diazacyclododecane 5, 1,4,10-trioxa-7,13-diazacyclopentadecane 6, 1,4,7,13-tetraoxa-10,16-diazacyclooctadecane 7, 1,4,10,13-tetraoxa-7,16-diazacyclooctadecane 8, 1,4,7-trioxa-10,13-diazacyclopentadecane 9 and 1,10-dioxa-4,7,13,16-tetraazacyclooctadecane 10 with Co2+, Ni2+, Cu2+ and Zn2+ ions. The values of the stability constants are discussed in terms of the relative size of the metal ion and macrocyclic cavities, the spatial arrangement of the donor nitrogen atoms and the macrocyclic effect.

Study of a method for the preparation of standard gas mixtures based on thermal decomposition of surface compounds. Application to isothiocyanates

Abstract Further development of a previously introduced concept for the generation of standard gas mixtures by thermal decomposition of surface-bonded residues is described. The method was applied to isothiocyanates, which are produced as the sole volatile product from silica gel-anchored dithiocarbamate groups.

Use of porous glass and silica gel as support media of a surface compound for generation of analytes in gaseous standard mixtures. New method for the determination of the amount of analyte generated.

The paper presents a new method for the determination of a volatile component of a gaseous standard mixture obtained by thermal decomposition of a suitable surface compound. The amount of the analyte generated (under given conditions of thermal decomposition) per unit of mass of the chemically modified material has been determined exclusively on the basis of measuring generation time. Therefore, the total error of the determination of the amount of a standard compound depends solely on the respective errors of weighing the material and measuring its decomposition time (both being direct measurements). This new method permits obtaining a few measuring points on the basis of a single sample of the material with chemically modified surface.