Interplay of Thermochemistry and Structural Chemistry,the Journal (Volume 13, 2002) and the Discipline

As practiced disciplines, structural chemistry and thermochemistry need not be related. In the current study they are: the contents of the journal Structural Chemistry (Vol. 13) for the year 2002 have been reviewed and then most articles that appeared therein were given a thermochemical commentary, spin or slant.     

Interplay of Thermochemistry and Structural Chemistry, the Journal (Volume 11, 2000), and the Discipline

As practiced disciplines, structural chemistry and thermochemistry need not be related. In the current study they are: the entire contents of the journal Structural Chemistry (Vol. 11) for the year 2000 has been reviewed and then each and every article that appeared therein was given a thermochemical commentary, spin or slant.     

Natural flavours of wine: correlation between instrumental analysis and sensory perception

Summary The aroma of wine consists of 600 to 800 aroma compounds from which especially those, typical for the variety, are already present in the grapes. The aroma extracts — received by extraction with trichlorofluoromethane — are separated by gas chromatography. There are significant varietal differences between the aromagrams (fingerprint pattern). Thus the amount of some flavour compounds (key substances) shows typical dependence on the variety. Especially monoterpene compounds play an important role in the differentiation of wine varieties.The German white wines can be differentiated into three groups only by quantitative determination of 12 monoterpenes (terpene profile). These groups are: Riesling type, Muscat type and Silvaner-Weißburgunder type. Such terpene profiles are also useful for the separation of real Riesling wines from others called Riesling (e.g. Welschriesling, Kap Riesling, Emerald Riesling) but not produced from grapes of the variety Riesling. Including further components and by means of statistical methods as for example linear discriminant analysis even the different varieties within the mentioned groups (for instance the Riesling-group: Riesling, Kerner, Ehrenfelser, Bacchus, Müller-Thurgau) can be separated from each other.To identify compounds causing off-flavours the sniffing technique is the method of choice. The off-flavour is pinpointed during gas chromatography separation of the complex aroma mixture by effluent sniffing. Once allocated, the chemical nature of the off-flavours is elucidated by spectroscopic methods. Substances contributing to the green pepper taint, the strawberry note, mousiness, corkiness etc. in wine could be found in this way.     

Computer-aided library search of combined LC-Retention and diode-array-UV-spectral data

An automated library search system for computer-aided identification of organic compounds using combined UV-spectral and LC-retention data, as acquired by HPLC with linear diodearray-UV-detection, is presented.The keystone of the system is a set of similarity indices which have been developed on the basis of mathematical-statistical models of the reproducibility of the spectral and retention data. The similarity indices have the form of a significance probability, a quantity originating from the general theory of hypothesis testing. The output of the LC-UV retrieval system is a compound identity or a list of identities (if any) for which the relevant similarity index has a value above a preset threshold. The data base used in this investigation contained 186 sets of UV-spectral and LC-retention data of 74 organophosphorus pesticides measured from standard solutions under various experimental conditions. A test set consisted of 186 alternative data sets of the same compounds as contained in the data base, however measured under different experimental conditions. The performance of the LC-UV reproducibility-based retrieval (LUVRR) system was evaluated using recall/reliability plots. The results appeared to be quite promising: for 95% of the unknowns, the target reference (correct positive) was on top of the hit list with a similarity index value being significantly higher than values found for false positives.The software is written in Pascal. The present (experimental) version of the system runs on a Data General Eclipse MV/4000 minicomputer.     

An investigation of micro-brownian motions in polydimethylsiloxane by complementary incoherent-neutron-scattering and nuclear-magnetic-resonance experiments below room temperature

Two different experimental methods, neutron scattering and nuclear magnetic resonance are used to investigate the random methyl group and segmental rotational jump motions in polydimethylsiloxane. It is shown that nuclear magnetic relaxation and line width experiments are complementary to incoherent neutron scattering fixed-window experiments, the principle of the fixed-window experiments being discussed in somewhat detail. Satisfactory agreement of these experimental techniques is achieved as to the determination of the two model parameters of the motional processes in question, i. e. the activation energy and the preexponential factor of the Arrhenius ansatz made for the correlation time or jump time, respectively.Contribution partly presented during the meeting of the Macromolecular Club, June 8–10, 1983 in Uppsala, the spring conference of the Deutsche Physikalische Gesellschaft, March 12–17, 1984 in Münster and the Fourth International Seminar on Polymer Physics, October 22–26, 1984 in Eyba (GDR).     

Determination of molecular properties by the method of moments

Some precautions needed in the choice of weight functions when calculating wave functions by the method of moments are analysed. It appears that an important criterion for good weight functions is that the difference between the total and the truncated overlaps (both defined in the paper) be high.The method of moments is applied to wave functions involving Hylleraas-type correlation factors using weight functions made up of products of single-particle orbitals. The aim of the calculations is partly to test the criteria for good weight functions, partly a preparation of more extended calculations of a similar type.The new name of the institute is: Computer Application Research and Development Center of the Chemical Industries.     

Production of submicron-sized multihollow polymer particles by alkali/cooling method

Submicron-sized styrene-methacrylic acid copolymer particles, which were produced by emulsion copolymerization, were changed to those having multihollow structure by treating stepwise the emulsion as follows. First alkali treatment was carried out at higher temperature than the glass transition temperature and subsequently the emulsion was cooled by keeping it at room temperature. This was named alkali/cooling method. The effects of methacrylic acid content, pH, time and temperature in the alkali treatment on the formation of multihollow structure were clarified.Part CLV of the series Studies on suspension and emulsion     

The diagram lattice as structural principle A. New aspects for representations and group algebra of the symmetric group B. Definition of classification character,mixing character,statistical order,statistical disorder; A general principle for the time evolution of irreversible processes

It is the aim of this paper to demonstrate the significance of the diagram lattice. This lattice was defined in order to achieve structural insight into the phenomenon of chirality in chemistry. In this context, Theorie der Chiralitätsfunktionen [1] may serve as reference. In the introduction of the present paper a summary of the relevant theorems and definitions is given and a few examples of the diagram lattice are graphically illustrated. Parts A and B can be read independently and presuppose knowledge only of the introduction. Part A is of special interest for mathematicians, Part B and [1] for physicists and chemists.In Part A theorems on the representations of the group _n and certain subgroups of it and on the structure of the group algebra are developed. In Part B the concept classification character with the two complementary aspects of identification and distinction is derived. With the interpretation mixing character the partial order relation gains an interpretation through a mixing process, which can be expressed by a bistochastic matrix. This results in another equivalent definition of the diagram lattice. Interpreted as mixing character of a statistical distribution a diagram represents statistical order and statistical disorder by its row partition and column partition respectively. These concepts and the corresponding lattice structure lead to the hypothesis of growing mixing character as a criterion for the time evolution of isolated systems. The criterion of increasing entropy provides a much weaker condition. A discussion of the master equation leads to a proof of the principle of growing mixing character.[/p]     

Plutonium in soils, bottom sediments and lichen near peaceful nuclear explosion sites in the Republic of Sakha (Yakutia)

During the 1974–1987 period 12 paceful nuclear explosions were conducted in the Republic of Sakha (Yakutia). For the first time^239,240Pu and²³⁸Pu concentrations were determined in samples of soils, bottom sediments and lichen taken at the Craton-3 and Crystal nuclear explosion sites. At the Craton-3^239,240Pu concentrations in the range 6.2 mBq/g to 5.9 Bq/g samples of soil and^239,240Pu concentrations up to 7.4 Bq/g in samples of lichen were observed.^239,240Pu concentration measurements in bottom sediments of a stream washing out the banking around the borehole of Craton-3 show that plutonium migrates in the direction of the Markha river. At the Crystal site local plutonium concentrations up to 35 Bq/g in soil and 1.8 Bq/g in lichen were observed.     

Preparation of La(OH)3 colloids and tactoid structures

Summary Lanthanum(III) hydroxide colloids have been prepared by in situ and repeptization method. The in situ colloids were aggregated in schiller layers. The formation of the sol is a relatively slow process which accounts for a good uniformity of the particles size. The characteristic lateral array of the colloidal particles in Schiller layers could be destroyed by simple shaking the sample. Lanthanum(III)hydroxide sols prepared by the repeptization method were needle-shaped and not tactoidally orientated.

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Zusammenfassung Lanthan(III)hydroxid-Kolloide wurden in situ und durch Repeptisation hergestellt. Eine regelmäßige Aggregation der Kolloidteilchen wurde nur bei in situ bereiteten Solen beobachtet (SchillerSchichten). Die Bildung der Sole ist ein verhältnismäßig langsamer Prozeß, was mit der ziemlich engen Verteilung der Teilchengr6ßen zusammenhängen k6nnte. Die Schiller-Schichten werden durch Schütteln zerstört. Ein durch Repeptisation gebildetes Lanthan (III)hydroxid war nadelförmig ausgebildet und nicht taktoidal aggregiert.

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With 5 figures

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*) Our thanks are due to Dr. N. LjubeN for the electron microscopy work.     

Determination of total,and bound Se in sera by INAA

In this study we report on the comparison between the total selenium in serum (total Se) with that which is apparently bound to high molecular weight (>12,000 D) species, presumably proteins (bound Se). Nine hundred seventy seven (977) serum samples arising out of a population-based epidemiological study were prepared in duplicate for the determination of total Se by pipeting directly into irradiation vials; and separate duplicate aliquots were dialyzed against DI water for the determination of bound Se. All samples were analyzed by neutron activation analysis via^77mSe (17.4 s). A small dialyzable Se component (6%) (free Se), defined as the difference between the total Se minus the bound Se, was identified.     

Heterocyclic analogs of pleiadiene

1,2-Disubstituted perimidine and aceperimidine methiodides react with aqueous alkali solutions to give pseudo bases corresponding to the acyclic form.See [1] for communication IX.Deceased.The letters a and b in formulas I–V pertain, respectively, to the perimidines and aceperimidines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 849–851, June, 1973.     

Structural Transformations in Polydisperse Ferrofluids

Real polydisperse ferrofluid is modeled by a bidispersed magnetic colloid composed of large and small particles. It is assumed that the energy of magnetodipole interaction for small particles is much lower and that of large particles is substantially higher than their thermal energy. Therefore, large particles can combine into the chain and droplet aggregates that are present in a sea of small particles. The influence of small particles on the structurization in the ensemble of large particles is studied. It is shown that small particles can either prevent or stimulate these structural transformations depending on the parameters of a medium.     

Chromogenic Receptors: Versatility of the Colorimetric Recognizing Behavior

This article briefly reviews our recent achievement in developing synthetic chromogenic receptors which are characterized by combining recognition and optical sensing functions; synthesis of several kinds of azomethine-derived calixarenes is described, as well as some colorimetric recognizing behavior for chemically or biologically significant guests ranging from cations to chiral amine derivatives.     

Gas-liquid chromatographic determination of ethanol in “Alcohol-Free” beverages and fruit juices

Summary A rapid, sensitive and direct method is described for the detemination of ethanol in Alcohol-Free beverages and fruit juices. A known amount of internal standard is added to the sample and a 0.1 mm³ aliquot is injected directly into a gas chromatograph. Ethanol concentrations as low as 0.005% v/v can be detected and quantitatively determined. Five brands of beer, seven brands of grape juice and four brands of apple juice; all labelled Alcohol-Free were analyzed. Ethanol in concentrations ranging from 0.009% v/v to 0.385% v/v was found. These findings indicate that these products are not actually Alcohol-Free but alcohol-low or alcohol-poor.     

The structures of macrocyclic heterocyclophane inclusion complexes

Crystal and molecular structures of (1:1) molecular complexes of N,N,N,N-tetramethyl-2, 11, 20, 29-tetraaza [3.3.3.3] paracyclophane (1) with CHCl₃, CH₂Cl₂, CH₃CN and CO₂ are reported. The macrocycle has square-box structure, giving hydrophobic cavity surrounded by four benzene rings. The guest molecules are included in the cavity. The uncomplexed1 was found to have a rectangular form, indicating large conformational flexibility of1. In solution,1 is achiral because rapid RS interconversion, but in solid, the macrocyclic conformation is frozen as R-conformer or S-conformer. The macrocycles with the same chirality are stacked alongb-axis to form chiral molecular columns, R-colums or S-columns. Complexes of1 crystallize differently depending on the guest molecules. R-columns (S-columns) packed alonga-axis produce R-layers (S-layers), which are further packed alongc-axis using R-layer to R-layer contact (RR) or SS and RS or SR. The crystals of1·CHCl₃ are formulated as--RRR--=[R]_n (Type I, chiral) and those of1·CH₃CN or1·CO₂ and1·CH₂Cl₂ are represented by [RS]_n (Type IIA, racemic) and [RRSS]_n (Type IIB, racemic), respectively.     

Flow injection-mini-column technique with ICP-AES detection for the isolation and preconcentration of the fast reactive aluminium fraction in waters

A flow injection mini-column system based on short reaction times with 8-hydroxyquinoline (oxine) with ICP-AES detection is described for the isolation and preconcentration of the fast reactive or toxic aluminium fraction in water samples. Using a 3 s reaction time with oxine (5 × 10^–4 mol/l) at pH 5.0, the fast reactive aluminium fraction is shown not to include the non-toxic AlF²⁺ species at low F^–: Al³⁺ molar ratios (0.3 : 1). The complexed aluminium is isolated in a stable and recoverable form on mini-columns of Amberlite XAD-2 (0.3 cm × 5.0 cm, resin particle size range 0.08 mm–0.16 mm)). The retained aluminium is recovered by back-flushing the analytical column with 1 mol/l HCl for final element specific detection by ICP-AES. Detection limits (after preconcentration) of 2 g/l, a linear range of 0–500 g/l, and possible preconcentration factors of up to 18 times are demonstrated with the present system. Implications for the possible solution of sample stability problems encountered with labile aluminium species analysis and the development of a field sampling technique are discussed, where the desired Al fraction is quantitatively retained in a stable form on mini-columns.     

Zur Frage des Einsatzes ionenspezifischer Elektroden in der Automation

Zusammenfassung Es wurden Untersuchungen mit anionenspezifischen Membranelektroden nach Pungor durchgeführt. Dazu werden Reproduzierbarkeit, Eichfunktion, Einstellzeiten bei auf- und absteigender Konzentration und Querempfindlichkeit im Hinblick auf den Einsatz in automatischen Systemen behandelt. Es wird vorgeschlagen, für die Angabe der Selektivität einen p-Sel analog zum pH zu verwenden, die Behandlung eines Analysensensorsystems wird vorgenommen.

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On the use of ion-specific electrodes in automation

Investigations on anion-specific membrane electrodes are described. Problems of reproducibility, calibration, time-response in respect of in- and decreasing concentrations and sensitivity to interfering ions are demonstrated and discussed with regard to automation. It is proposed to define a p-sel for the selectivity constant analogue to pH and a calculation method for an Analysis-Sensor-System is shown.

     

4,4'-Diaminodiphenyl Sulfone,a Substituted Troger Base,and Its Functionalization by the Amino Group

Racemic mixtures of previously unknown chiral tweezers with a rigid asymmetrical diazocine bridge (Troger base) were synthesized on the basis of 4,4'-diaminodiphenyl sulfone. The Troger base was condensed with 2,4-dihydroxybenzaldehyde and 4-formylbenzoic acid to obtain new aromatic chelate cavities.     

Porous glassy carbon,a new columns packing material for gas chromatography and high-performance liquid chromatography

Summary A new carbon for liquid and gas chromatography, called porous glassy carbon (PGC) is described. The material is made using a porous template filled with carbonizable resin. After firing in an inert atmosphere the template is removed. PGC has been made with surface area ranging from 20 m²/g to 400 m²/g. It is of adequate strength for gas and high-performance liquid chromatography. In gas chromatography it is similar to the commerical graphitized thermal carbon black (GTCB) Carbopack B, but has somewhat less retention per unit surface area and is much more robust. It gives symmetrical peaks for hydrocarbons with k-values up to at least 100. In liquid chromatography it is similar to the GTCB's coated with pyrolytic carbon described by Guiochon. It behaves as a strong reversed phase adsorbent. Fairly good peak symmetry is maintained for k-values up to at least 10 but trace additives to the eluent may be necessary to control peak asymmetry. PGC has considerable potential as a new packing material in both gas and liquid chromatography.Presented at the 14th International Symposium on Chromatography London, September, 1982