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Attempts to prepare fluorinated 5-aryl-1H-tetrazoles by various methods were successful for (3,5-bis(trifluoromethyl)phenyl)tetrazole (BTFTH) and in part for 5-pentafluoropenyltetrazole (F5PhTetH) and 5-(tetrafluoro-4-pyridinyl)tetrazole (F4PyTetH). For BTFTH, several different methods gave satisfactory yields and purity. For the other compounds, the same methods allowed only the observation of the desired species in very small quantities in ill-defined reaction product mixtures with azidodefluorination being the dominant side reaction. Negative ionising MS proved to be superior to other MS methods showing clean elimination of mainly N2 and CF2 from the tetrazolate anions. From BTFTH, the Cu complex [(BTFT)2Cu(Py)2]n could be obtained and fully characterised, including crystal structure determination (for the complex and the ligand). Magnetic and EPR data for the polymeric [(BTFT)2Cu(Py)2]n suggest that the superexchange (SE) between the Cu2+ ions (S = ½) is negligible. This can be understood by examining the crystal structure and the details of the possible SE path.

The reactions of iodoperfluoroalkanes CnF2n+1I (n = 2, 3, 4) and n-BuLi at low temperatures give NMR spectroscopic evidence for LiCnF2n+1 which were converted into LiCu(CnF2n+1)2 derivatives upon treatment with 0.5 mol copper(i) bromide, CuBr. An alternative route to obtain perfluoroorgano copper couples, Cu(Rf)2Ag (Rf = n-C3F7, n-C4F9, C6F5) was achieved from the reactions of the corresponding perfluoroorgano silver(i) reagents, AgRf, and elemental copper through redox transmetallations. The composition of the resulting reactive intermediates was investigated by means of (19)F NMR spectroscopy and ESI mass spectrometry. Perfluoro-n-propyl and perfluoro-n-butyl copper-silver reagents prepared by the oxidative transmetallation route exhibited good properties in C-C bond formation reactions with acid chlorides even under moderate conditions. Substitution of bromine directly bound to aromatics for perfluoroalkyl groups was achieved at elevated temperatures, while success in halide substitution reactions using lithium copper couples remained poor.

The morphology and structure of biological nanoparticles, such as viruses, can be efficiently analysed by transmission electron microscopy (TEM). To chemically characterise such nanoparticles in heterogeneous samples at the single particle level, we suggest tip-enhanced Raman spectroscopy (TERS) as a correlative method. Here we describe a TERS-compatible staining procedure for TEM which involves sample pre-scanning by TEM imaging, nanoparticle relocalisation by atomic force microscopy (AFM) followed by spectroscopic characterization of the virus nanoparticles using TERS. First successful correlative measurements are demonstrated on tobacco mosaic virus particles deposited on silicon-based TEM sample supports. In addition, the advantages and problems of this methodology are discussed.

Conditions for the addition of trialkyl(trifluorovinyl)silanes to the carbonyl- and thiocarbonyl function of commercially available isocyanates and isothiocyanates in the presence of tetramethylammonium fluoride (TMAF) to give corresponding amides of 2,3,3-trifluoroacrylic and 2,3,3-trifluorothioacrylic acids have been elaborated. The behaviour of the synthesized amides towards fluoride ions was studied. The syntheses of the amides of 2,3,3,3-tetrafluoropropionic and 2,3,3,3-tetrafluorothiopropionic acids and some unexpected cyclic products with the β-lactam structure are described. The molecular structures of the c -hexyl amide of 2,3,3,3-tetrafluoropropionic acid and two isomers of β-lactams deriving from the reaction of the tert -butyl amide of 2,3,3-trifluoroacrylic acid with a fluoride source have been elucidated by XRD measurements.

Se(C5F4N)2 and Te(C5F4N)2 were prepared via redox transmetalations of AgC5F4N and the corresponding elements in good yields. The crystal structures of both derivatives exhibit infinite chains caused by a weak intermolecular contact between the chalcogen and one nitrogen atom with a T-shaped (ψ-pentagonal-bipyramidal) ligand arrangement. Crystallization of both reagents from dimethylsulfoxide gave single crystals of the corresponding 1:1 adducts that crystallize in infinite chains best expressed by the formula [E(C5F4N)2·(μ-DMSO)]∞ (E = Se, Te). In these cases, the coordination spheres of selenium and tellurium are square-planar (ψ-octahedral). Similar effects are found in the molecular structures of [Te(C5F4N)2·TMTU]∞ and [Te(C6F5)2·TMTU]∞ (TMTU = tetramethylthiourea). Differences in the Te–S interatomic distances clearly indicate the C5F4N ligand being significantly more electron-withdrawing in comparison with the C6F5 group; that is, Te(C5F4N)2 is the stronger Lewis acid.

MeTeRf (Rf = CF3, C2F5) can easily be prepared via the reactions of methyl iodide and the corresponding tetramethylammonium perfluoroalkyltellurates(0), [NMe4]TeRf (Rf = CF3, C2F5). Both compounds are easily oxidized by xenon difluoride and the heavier halogens to yield the corresponding dihalides, MeTe(Rf)X2 (X = F, Cl, Br, I) and by ArI(OCOCF3)2 to give the corresponding trifluoroacetates, MeTe(Rf)(OCOCF3)2. All compounds are characterized byspectroscopic means. The molecular structures of MeTe(Rf)F2,MeTe(Rf)Cl2, MeTe(Rf)Br2, and of 4-MeC6H4I(OCOCF3)2 were elucidated by XRD methods.

An alternative copper halide-free route to obtain highly reactive trifluoromethylcopper species has been developed via the reaction of silver fluoride and trimethyl(trifluoromethyl)silane followed by a redox transmetallation with elemental copper. The composition of the reactive intermediate was investigated by means of UV/Vis/NIR, ESR, 19F NMR spectroscopy and ESI mass spectrometry. “Trifluoromethylcopper” prepared by the oxidative transmetallation route exhibits excellent reactivity and selectivity in substitutions of iodine or bromine bond to aromatic or heterocyclic compounds for trifluoromethyl groups without any additional catalyst.

Inflammatory processes are accompanied by the post-translational modification of certain arginine residues to yield citrulline, and a pH decrease in the affected tissue, which might influence the protonation of histidine residues within proteins. We employed isotope-edited IR spectroscopy to investigate whether conformational features of two human major histocompatibility antigen class I subtypes, HLA-B*2705 and HLA-B*2709, are affected by these changes. Both differ only in residue 116 (Asp vs. His) within the peptide-binding grooves, but are differentially associated with inflammatory rheumatic disorders. Our analyses of the two HLA-B27 subtypes in complex with a modified self-peptide containing a citrulline RRKWURWHL (U = citrulline) revealed that the heavy chain is more flexible in the HLA-B*2705 subtype than in the HLA-B*2709 subtype. Together with our previous studies of HLA-B27 subtypes complexed with the unmodified self-peptide RRKWRRWHL, these findings support the existence of subtype-specific conformational features of the heavy chains under physiological conditions, which are undetectable by X-ray crystallography and exist irrespective of the sequence of the bound peptide and its binding mode. They might thus influence antigenic properties of the respective HLA-B27 subtype. Furthermore, a decrease in the pH from 7.5 to 5.6 during the analyses had an influence only on HLA-B*2709 complexed with the unmodified self-peptide, where His116 is not contacted by any peptide side chain. This permits us to conclude that histidines, and in particular His116, influence the stability of MHC:peptide complexes. The conditions prevailing in inflammatory environments in vivo might thus also exert an impact on selected conformational features of HLA-B27:peptide complexes.

Hexacarbonyltungsten and -chromium [M(CO)6; M = W, Cr] react smoothly with perfluoroalkyl (Rf = CF3, C2F5) and trifluorovinyl (Rf = CF=CF2) silanes in the presence of equimolar amounts of fluoride ions with exclusive attack of one of the CO ligands to form the corresponding salts, Cat[(CO)5MC(Rf)O] (Cat = [Me4N]+, [Cs(15-crown-5)2]+) which after methylation represent the first hitherto unknown perfluoroorgano-substituted Fischer carbene complexes, (CO)5MC(Rf)(OCH3), of those metals. The methoxy group can be easily replaced by amino functional groups as shown for the corresponding carbonyltungsten compound. The molecular structures of (CO)5WC(CF3)(OCH3) and (CO)5WC(CF3)[N(C2H5)2] have been elucidated by XRD measurements.

Although the addition of sugars to drying media is a general practice for the viability improvement of lactic acid starter cultures during drying, the mechanism behind the protective effects is not clear. To gain insight into the protective mechanisms of sugars, Lactobacillus helveticus was dried by vacuum drying in the presence of sorbitol, whose protective effects were shown in our previous study (Santivarangkna et al. Lett Appl Microbiol 42:271–276, 2009). In this study, membrane phase transition temperatures (Tm) of fresh cells and cells dried with and without sorbitol were measured by Fourier transform infrared spectroscopy (FT-IR). Generally, an increase in membrane phase transition temperature (Tm) is believed to cause membrane damage during drying. Lactobacillus helveticus cells exhibited the transitions at the temperatures of 15.5 and 37.5°C. Drying of cells without sorbitol increased the transition temperatures to 16.5 and 41.5°C, while it was depressed by 6 and 10.5°C when dried with sorbitol. The interaction between membrane phospholipids and sorbitol was observed from hydrogen-bonding sensitive C = O and P = O stretching bands. The position of the P = O band was shifted to the lower frequency in cells dried with sorbitol, which reflects the hydrogen bonding interaction. We suggest that sorbitol protects cells during drying by depressing Tm via the interaction with phosphate groups of membranes.

Plant and microbial toxins such as ricin, staphylococcal enterotoxin B (SEB), and the botulinum neurotoxins (BoNT) are considered as potential biological warfare agents. Specific screening methods are, therefore, required that enable unambiguous and sensitive identification of these biohazards, particularly for the occurrence of the toxins in complex sample matrixes. The present study describes a combination of a multiplex-immunoaffinity purification approach, followed by matrix-assisted laser desorption/ionization (MALDI)-based detection for the simultaneous identification of ricin, SEB, BoNT/A, and BoNT/B. The method comprises an affinity enrichment step, using specific monoclonal antibodies for each of the four toxins which have been selected from a pool of antibodies. The selected antibodies allow for specific and simultaneous capture of ricin, SEB, BoNT/A, BoNT/B, and the corresponding BoNT complexes. These were subsequently identified by MALDI time-of-flight (TOF) mass spectrometry (MS), following tryptic digest. The sensitivity of the technique was approximately 500 fmol for each of the toxins. These toxins were detectable within 8 h, even when present in complex matrixes such as milk or juice. Furthermore, the MALDI-based multiplex assay allowed for the discrimination of closely related BoNT sero- and subtypes, including a real case of food-borne botulism in Germany.

This article does not attempt to offer an exhaustive assessment of the current status of terahertz technology, nor does it endeavour to cover all the anticipated applications of terahertz science, rather it is an attempt to raise the awareness of this tool among those molecular spectroscopists who may not yet have considered the emerging opportunities offered by this window in the electromagnetic spectrum.

The reactions of aromatic ketones with trialkyl(trifluorovinyl)silanes in the presence of fluoride ions were studied. The conditions for the selective addition of trialkyl(trifluorovinyl)silanes to the carbonyl function of aromatic ketones in the presence of cesium fluoride and absence of any solvents to form the trifluorovinyl containing “silylated” alcohols have been worked out. The analogous reactions in common organic solvents are not terminated on the stage of “silylated” alcohols formation; consecutive reactions lead to fluorinated olefins and acids under the influence of fluoride ions.

Trifluoromethylcopper and pentafluoroethylcopper are prepared conveniently via the reaction of the solid complex Zn(CF 3 )Br·2DMF with copper(I) bromide in N,N-dimethylformamide. The reactions of both copper species with 2,4-dinitrochlorobenzene, 4-iodonitrobenzene, 4-nitrobenzyl iodide, 4-bromobenzoic acid ethyl ester, 4-iodobenzoic acid ethyl ester, 2-iodopyridine and 2-iodopyrimidine have been studied. The structure of 2,4-dinitrotrifluoromethylbenzene has been elucidated.

This report demonstrates the applicability of a combination of matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) and chemometrics for rapid and reliable identification of vegetative cells of the causative agent of anthrax, Bacillus anthracis. Bacillus cultures were prepared under standardized conditions and inactivated according to a recently developed MS-compatible inactivation protocol for highly pathogenic microorganisms. MALDI-TOF MS was then employed to collect spectra from the microbial samples and to build up a database of bacterial reference spectra. This database comprised mass peak profiles of 374 strains from Bacillus and related genera, among them 102 strains of B. anthracis and 121 strains of B. cereus . The information contained in the database was investigated by means of visual inspection of gel view representations, univariate t tests for biomarker identification, unsupervised hierarchical clustering, and artificial neural networks (ANNs). Analysis of gel views and independent t tests suggested B. anthracis - and B. cereus group-specific signals. For example, mass spectra of B. anthracis exhibited discriminating biomarkers at 4,606, 5,413, and 6,679 Da. A systematic search in proteomic databases allowed tentative assignment of some of the biomarkers to ribosomal protein or small acid-soluble proteins. Multivariate pattern analysis by unsupervised hierarchical cluster analysis further revealed a subproteome-based taxonomy of the genus Bacillus . Superior classification accuracy was achieved when supervised ANNs were employed. For the identification of B. anthracis , independent validation of optimized ANN models yielded a diagnostic sensitivity of 100% and a specificity of 100%.

The development of fast identification techniques of viruses is an ongoing important research topic. Conventional virus detection and identification is generally based on various different microbiological methods. However, these techniques are not suitable for the analysis of single virus particles. Therefore, our goal is to establish tip-enhanced Raman scattering (TERS), providing vibrational spectroscopic information with a spatial resolution less than 50 nm, to characterize single viruses at a molecular level. Here we report, to the best of our knowledge for the first time, about TERS spectra of a tobacco mosaic virus, showing the great capability of this technique. However, the application of the TERS technique for a rapid and direct detection of different species of single viruses is under development, which is useful for a wide range of analytical fields. Copyright © 2008 John Wiley & Sons, Ltd.

Scrapie is a neurodegenerative disorder that involves the misfolding, aggregation and accumulation of the prion protein (PrP). The normal cellular PrP (PrP(C)) is rich in alpha-helical secondary structure, whereas the disease-associated pathogenic form of the protein (PrP(Sc)) has an anomalously high beta-sheet content. In this study, protein structural changes were examined in situ in the dorsal root ganglia from perorally 263K scrapie-infected and mock-infected hamsters using synchrotron Fourier Transform InfraRed Microspectroscopy (FTIRM) at four time points over the course of the disease (pre-clinical, 100 and 130 days post-infection (dpi); first clinical signs ( approximately 145 dpi); and terminal ( approximately 170 dpi)). Results showed clear changes in the total protein content, structure, and distribution as the disease progressed. At pre-clinical time points, the scrapie-infected animals exhibited a significant increase in protein expression, but the beta-sheet protein content was significantly lower than controls. Based on these findings, we suggest that the pre-clinical stages of scrapie are characterized by an overexpression of proteins low in beta-sheet content. As the disease progressed, the beta-sheet content increased significantly. Immunostaining with a PrP-specific antibody, 3F4, confirmed that this increase was partly - but not solely - due to the formation of PrP(Sc) in the tissue and indicated that other proteins high in beta-sheet were produced, either by overexpression or misfolding. Elevated beta-sheet was observed near the cell membrane at pre-clinical time points and also in the cytoplasm of infected neurons at later stages of infection. At the terminal stage of the disease, the protein expression declined significantly, likely due to degeneration and death of neurons. These dramatic changes in protein content and structure, especially at pre-clinical time points, emphasize the possibility for identifying other proteins involved in early pathogenesis, which are important for a further understanding of the disease.

The reactions of non-activated aldimines with trimethyl(trifluoromethyl)silane and 1 equiv. of tetramethylammonium fluoride proceed via the formation of tetramethylammonium amides which were identified by low-temperature 19F NMR experiments. Consecutive reactions of the salts formed in situ with electrophiles yielded trifluoromethylated amines. Fluoride elimination is observed in the absence of electrophilic substrates leading to the formation of difluoromethylated ketimines.

A convenient synthesis of the 1,3-dihydro-1,3,3-tris(perfluoroalkyl)isobenzofuran-1-ols 3a,b was elaborated starting from commercially available phthaloyl dichloride and trimethyl(perfluoroalkyl)silanes (Me3SiRf) 1a,b (Rf=CF3, C2F5) in the presence of a fluoride source (Schemes 1 and 3). In a reaction analogous to alkyl Grignard reagents, double chloride substitution by two perfluoroalkyl groups and subsequent addition of one perfluoroalkyl group with concomitant ring closure led to this new class of compounds (Scheme 2). The syntheses of the alcohols and some alcoholates, as well as of the corresponding trimethylsilyl ethers are described. A combination of special 1D and 2D NMR experiments allowed the assignment of all atoms of the new compounds. The solid-state structure of 1,3-dihydro-1,3,3-tris(trifluoromethyl)isobenzofuran-1-ol (3a) was elucidated by X-ray diffraction methods.

Trifluoromethylketones of aromatics, heteroaromatics and olefins are formed selectively from reactions of trifluoromethylsilver and the corresponding carboxylic acid chlorides in moderate to excellent yields. The conditions chosen are dependent on the nature of the acyl chloride. Attempts to prepare alkyl(trifluoromethyl)ketones yielded product mixtures of the corresponding acyl fluorides, trifluoromethyl-, pentafluoroethyl- and n -heptafluoropropyl ketones.

The unique pseudo-trigonal-bipyramidal CF3PF3O– and (CF3)2PF2O– anions were obtained and characterised for the first time. They were formed by the reactions of (PhO)3P(O), Me3SiCF3 and the fluoride ion sources [Me4N]F and CsF, respectively, in glyme. These anions represent the stable transition states postulated for nucleophilic substitution at a tetrahedral phosphorus atom. The salt Cs[(CF3)2PF2O] (7) is stable at room temperature for a month, while [Me4N][CF3PF3O] (1) dismutates into [Me4N][CF3PF(O)O] (2) and [Me4N][CF3PF5] (3) above 0 °C. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Rapid identification of non-tuberculous mycobacteria (NTM) species is important in clinical laboratories to stipulate the appropriate therapy and to offer a comprehensive infection control. We applied Fourier-Transform Infrared microspectroscopy to evaluate, whether the most frequent species of NTM can be rapidly and uniformly identified by this method using microcolonies of NTM growing on solid nutrient agar plates. To establish a standardized protocol, the heterogeneity of cell growth within the microcolonies and the reproducibility of measuring the IR spectra from whole mycobacterial microcolonies were first studied. Hierarchical cluster analysis applied to spectra obtained by linear mapping across microcolony imprints from fast- and slow-growing NTM revealed only little spectral variance between the various microcolony zones. In parallel, when repetitive measurements were performed on independently grown whole single microcolonies with diameters of 80 and 140 μm, excellent reproducibility could be achieved, verifying that mycobacterial microcolonies are well suited for FT-IR-based identification. Twenty-eight different and well-defined strains, comprising the most frequent species of NTM isolated in clinical laboratories, were used to create a classification system based on FT-IR spectra from single microcolonies. Hierarchical cluster analysis allowed the assignment of all isolates measured in replicates to their correct species-specific clusters. Additionally, a clear separation of all strains into strain-specific sub-clusters was observed. These results demonstrate the potential of FT-IR microspectroscopy to rapidly differentiate NTM at the species and strain level. The data so far obtained suggest that an extended spectral database, containing more NTM strains and covering a broader biological variance, may provide a practical solution to rapidly identify unknown NTM isolates in routine clinical–microbiological laboratories with the additional possibility to type these microorganisms at the sub-species level.

Escherichia coli O123 strains express a broad spectrum of phenotypes, H serotypes and virulence markers and are able to colonize and to cause disease in different hosts including humans. In this study, two subtypes of E. coli O123 antigen (group I and group II) have been identified based on their cross-reactions with other E. coli O antigens. Investigation of the relationship between O123 group I and group II strains by O serotyping and Fourier transform infrared spectroscopy of whole bacteria revealed surface structural differences between these two groups of E. coli O123 strains. Nucleotide sequence analysis of the O-antigen gene clusters of two E. coli O123 strains representing O123 group I and group II revealed no change at the amino acid level. These findings indicate that the differences in the surface structures of group I and group II strains are not related to genetic heterogeneity in their O-antigen gene clusters. A PCR assay based on O123 antigen-specific wzx and wzy genes was developed and found to be suitable for reliable detection of all subtypes of E. coli O123 strains, which bears an advantage over traditional serological detection.

The anions [(TeCF3)2X]− (X = Cl, Br, I) resemble the trihalides [I2X]− in the solid state and show similar dynamic behaviour in solution. All three compounds crystallize iso-structurally in the triclinic space group with Z = 2 and exhibit cell dimensions according to the sizes of the halogen atoms.

Microorganisms rarely occur as individual cells in nature and are, instead, organized in complex multicellular communities such as colonies, fruiting bodies, or biofilms. Interest in the natural microbial life-style has increased during the last decade and a whole plethora of techniques has been used to gain insight into the development, structure and composition of diverse microbial communities. We have developed a technique for investigating the spatial heterogeneity of microbial growth in macro-colonies which essentially entails excision of the colonies with the underlying agar, freezing and subsequent cryotoming of the colonies, then FTIR microspectroscopic mapping of the cryosections. Colonies from Legionella, Bacillus, and Candida strains were chosen as model systems of multi-cellular communities to evaluate the technique. The results obtained indicate pronounced cell population heterogeneity even in relatively young colonies cultivated under laboratory conditions. Spectral data obtained from different positions within, e.g., a colony of Legionella bozemanii 120 h old indicated that levels of the storage material poly-beta-hydroxybutyric acid were significantly higher in cells at the surface of the colonies than in those growing at the bottom next to the agar surface. Similarly, in a 24-h-old macro-colony of Bacillus megaterium significantly more of the capsular compound polyglutamic acid was detected in upper layers than in deeper layers of the colony. Results demonstrate that FTIR microspectroscopy can be an useful tool for investigation of the spatial heterogeneity of cell growth within microbial macro-colonies. It is suggested that the method also can be adapted to the analysis of more complex multicellular communities, for example fruiting bodies, biofilms, or colonies growing under natural conditions.

In this study we describe a methodology for diagnosing preclinical scrapie infection in hamsters from serum by a combination of Fourier-transform infrared (FT-IR) spectroscopy and chemometrics. Syrian hamsters (Mesocricetus auratus) were orally inoculated with the 263K scrapie agent, or mock-infected, and sera were obtained at 70, 100 and 130 days post infection (dpi) and at the terminal stage of scrapie (160 +/- 10 dpi). The analysis of hamster sera by FT-IR spectroscopy and artificial neural networks (ANN) confirmed results from earlier studies which had indicated the existence of disease-related structural and compositional alterations in the sera of infected donors in the terminal stage of scrapie [Schmitt et al. (2002) Anal Chem 74:3865-3868]. Experimental data from sera of animals in the preclinical stages of scrapie revealed subtle but reproducible spectral variations that permitted the identification of a preclinical scrapie infection at 100 dpi and later, but not at 70 dpi. The IR spectral features that were discriminatory for the preclinical stages differed from those of the terminally ill individuals. In order to reliably identify scrapie-negative as well as preclinical (100 and 130 dpi) and terminal scrapie-positive animals, a hierarchical classification system of independent artificial neural networks (ANN) was established. A "toplevel" ANN was designed which discriminates between animals in the terminal stage of scrapie and preclinical scrapie-positive or control animals. Spectra identified by the "toplevel" ANN as preclinical or controls were then further analyzed by a second classifier, the "sublevel" ANN. Using independent external validation procedures, the toplevel classifier produced an overall classification accuracy of 98%, while the sublevel classifier yielded an accuracy of 93%, indicating that scrapie-specific serum markers were also present for preclinical disease stages. Possible spectral markers responsible for the discrimination capacity of the two different ANNs are discussed.

[2,6-F2C6H3Xe][BF4] is quantitatively transferred into 2,6-F2C6H3XeF in reactions with [NMe4]F. The latter has been isolated as a colourless solid which is stable in dichloromethane solution at room temperature for approximately 1 h. 2,6-F2C6H3XeF readily reacts with Me3SiX (X = Cl, Br, CN, NCO, OCOCF3, OSO2CF3, C6F5, 2,6-F2C6H3) to give compounds of general compositions 2,6-F2C6H3XeX which were identified by multinuclear NMR experiments. Evidence was found for C6H5Xe(2,6-F2C6H3) as a product of the reaction with C6H5SiF3.

Strain diversity in transmissible spongiform encephalopathies (TSEs) has been suggested to be “enciphered” in the structure of the misfolded prion protein isoform PrP Sc . We have recently demonstrated the strain typing potential of the FT-IR spectroscopy technique, analyzing four different TSE agents adapted to Syrian hamsters [A. Thomzig, S. Spassov, M. Friedrich, D. Naumann and M. Beekes, Discriminating scrapie and BSE isolates by infrared spectroscopy of pathological prion protein J. Biol. Chem. 279 (2004) 33847-33854.] [1]. In the present paper, we have extended the FT-IR study, exploring the secondary structure, temperature stability, and hydrogen–deuterium exchange characteristics of PrP27–30, from the TSE agents 263K, ME7-H, 22A-H, and BSE-H. The strain differentiation capacity of the FT-IR approach was objectively proven for the first time by multivariate cluster analysis. The second derivative FT-IR spectra obtained from dried protein films or samples hydrated in H 2 O or D 2 O consistently exhibited strain-specific infrared characteristics in the secondary structure sensitive amide I region, complemented by strain dependent spectral traits in the amide II and amide A absorption regions, and the different H/D-exchange behaviour of the various PrP27-30 samples. FT-IR spectra of PrP27–30 samples from 263K, ME7-H and 22A-H exposed to increasing temperature (up to 90 °C) showed that a strain-specific response to heat treatment is associated with strain specific thermostability of distinct secondary structure elements, providing additional means for TSEs strain discrimination.

The collection of IR spectra through microscope optics and the visualization of the IR data by IR imaging represent a visualization approach, which uses infrared spectral features as a native intrinsic contrast mechanism. To illustrate the potential of this spectroscopic methodology in breast cancer research, we have acquired IR-microspectroscopic data from benign and malignant lesions in breast tissue sections by point microscopy with spot sizes of 30–40 μm. Four classes of distinct breast tissue spectra were defined and stored in the data base: fibroadenoma (a total of 1175 spectra from 14 patients), ductal carcinoma in situ (a total of 1349 spectra from 8 patients), connective tissue (a total of 464 spectra), and adipose tissue (a total of 146 spectra). Artifical neural network analysis, a supervised pattern recognition method, was used to develop an automated classifier to separate the four classes. After training the artifical neural network classifier, infrared spectra of independent external validation data sets (“unknown spectra”) were analyzed. In this way, all spectra (a total of 386) taken from micro areas inside the epithelium of fibroadenomas from 4 patients were correctly classified. Out of the 421 spectra taken from micro areas of the in situ component of invasive ductal carcinomas of 3 patients, 93% were correctly identified. Based on these results, the potential of the IR-microspectroscopic approach for diagnosing breast tissue lesions is discussed.

Spatial resolution is one of the most critical measurement parameters in infrared microspectroscopy. Due to the distinct levels of morphologic heterogeneity in cells and tissues the spatial resolution in a given IR imaging setup strongly affects the character of the infrared spectral patterns obtained from the biomedical samples. This is particularly important when spectral data bases of reference microspectra from defined tissue structures are collected. In this paper we have also pointed out that the concept of spatial resolution in IR imaging is inseparable from the contrast. Based on infrared microspectroscopic transmittance data acquired from an USAF 1951 resolution target we have demonstrated how the spatial resolution can be determined experimentally and some numbers for the spatial resolution of popular IR imaging systems are provided. Finally, we have presented a new computational procedure which is suitable to improve the spatial resolution in IR imaging. A theoretical model of 3D-Fourier self-deconvolution (FSD) is given and advantages or pitfalls of this method are discussed. Based on synchrotron IR microspectroscopic data we have furthermore demonstrated that the technique of 3D-FSD can be successfully applied to increase the spatial resolution in a real IR imaging setup.

The series of cis / trans -trifluoromethylselenato complexes [Pt(SeCF 3 ) 2 − x Cl x (PPh 3 ) 2 ] ( x = 0, 1) was identified by NMR spectroscopic methods. While in acetonitrile solution spectra are dominated by the resonances of the cis derivatives, those of pure cis -[Pt(SeCF 3 ) 2 (PPh 3 ) 2 ] indicate cis – trans -isomerisation in CH 2 Cl 2 solution. In contrast, exchange reactions of cis -[PtCl 2 (PPh 3 ) 2 ] and [NMe 4 ]TeCF 3 only gave evidence for cis isomers. Molecular structures of cis - and trans -[Pt(SeCF 3 ) 2 (PPh 3 ) 2 ] and cis -[Pt(TeCF 3 ) 2 (PPh 3 ) 2 ] are discussed in comparison with related compounds.

A complete series of compounds with the anions [(TeCF3)(3-x)I(x)]- (x = 0-2) had been prepared and characterised in the solid state and by NMR spectroscopic methods. Dynamic behaviour in solution can be assumed for [(TeCF3)3]- and [(TeCF3)2I]-, while in the solid state all three bis(triphenylphosphoranyliden)ammonium (PNP) salts resemble structures found in triiodides. The molecular structures of [PNP][(TeCF3)(3-x)I(x)]- (x = 0-2) are discussed in comparison with [PNP]I3, I2, and Te2(CF3)2. On this basis, the structures of the [(TeCF3)3]- and [(TeCF3)I2]- ions are comparable to symmetric I3- ions, while the [(TeCF3)2I]- ion resembles an asymmetric I3- unit.

Ligand exchange reactions of cis-PtCl2(PPh3)2 and [NMe4]SCF3 in different ratios were studied. Depending on the stoichiometry reactions proceeded with formation of products expected for the chosen ratio, i. e. cis-Pt(SCF3)Cl(PPh3)2, cis-Pt(SCF3)2(PPh3)2, and [NMe4][Pt(SCF3)3(PPh3)]. Starting from cis-PtCl2(MeCN)2 and [NMe4]SCF3 and adding PPh3 after substitution, product mixtures were dominated by the corresponding trans-isomers. Results of the single crystal structure analyses of cis-Pt(SCF3)2(PPh3)2 and trans-Pt(SCF3)Cl(PPh3)2 are discussed.

Reactions of trimethyl(trifluoromethyl)silane in the presence of "naked" fluoride proceed up to a temperature of +5 degrees C mainly with formation of [Me3Si(CF3)2]-. A further rise of temperature up to about 20 degrees C gives evidence for the formation of a salt with the 1,1,1,2,3,6,6,6-octafluoro-2,4,4,5,5-pentakis(trifluoromethyl)hexan-3-ide anion. This intermediate decomposes at room temperature into the 1,1,1,3,5,5,5-heptafluoro-2,4-bis(trifluoromethyl)pentenide anion. The bis([15]crown-5)cesium salt, [Cs([15]crown-5)2][(CF3)2CCFC(CF3)2] has been characterized unambiguously as the stable final product of this reaction sequence. Thermal decomposition of this salt opens a convenient nontoxic route to obtain 1,1,3,3-tetrakis(trifluoromethyl)allene, (F3C)2C=C=C(CF3)2.

2,3,4,5,6-Pentafluorophenones are formed selectively from the reactions of pentafluorophenylsilver and carboxylic acid chlorides in moderate to excellent yields.

Ligand exchange reactions of [NMe4]SeCF3 or [Cs(15-Crown-5)2]SeCF3 with Ag[BF4] and AuCl gave the corresponding bis(trifluoromethylselenato(0))metallates [Ag(SeCF3)2]- and [Au(SeCF3)2]- in good yields. All compounds were characterized by NMR spectroscopic means and ESI mass spectrometry. Cation exchange with [PNP]Cl ([PNP] = bis(triphenylphosphoranylidene)ammonium) yielded the corresponding [PNP] salts. The single crystal structure of [PNP][Au(SeCF3)2] was elucidated by XRD measurements (P21/a; a = 1712.0(1), b = 1142.5(1), c = 2013.6(1) pm; β = 112.10(1)°; Z = 4).

Reactions of Me 3 SiC 6 F 5 and MF (M = Cs, [NMe 4 ]) in molar ratios varying from 1:1 to 2:1 in a temperature range between −70 °C and ambient proceed more or less selectively to form 1-H-perfluoro-4,4′-polyphenyls, 1-H(C 6 F 4 ) n F, independent of the solvent used (DME, THF). The silicates expected, M[Me 3 Si(C 6 F 5 )F] and M[Me 3 Si(C 6 F 5 ) 2 ], were not detected even in low temperature NMR experiments. The polymeric material formed was identified after aqueous working up as a mixture of 1-H(C 6 F 4 ) n F ( n = 4–13) by elemental analyses and EI mass spectrometric studies.

Transmissible spongiform encephalopathies (TSEs) such as scrapie are neurodegenerative diseases that are characterized by the accumulation of a misfolded prion protein. During the pathogenesis, the normally α-helical prion protein (PrP C ) refolds to the proteinase K-resistant abnormal form (PrP Sc ), which is high in β-sheet content. In this study, dorsal root ganglia from the 263K hamster model of scrapie were cut into 8 μm thin sections and mounted onto an aluminium-coated glass slide. Single neuronal cells were mapped with synchrotron infrared microspectroscopy to study protein structure and X-ray fluorescence microprobe to determine metal accumulation. Both techniques provide a spatial resolution of 5–10 μm. Results showed that some IR spectra of the infected cells exhibited a significant frequency shift of the amide I band, where an increased peak intensity was observed at ∼1631 cm −1 (attributed to β-sheet) and a decreased peak intensity at ∼1658 cm −1 was also seen (attributed to α-helix). These shifts were not observed in non-infected cells. Adjacent sections were also stained with an antibody for the prion protein in order to confirm that the IR observations were associated with accumulated PrP Sc . Finally, the same cells were measured by X-ray fluorescence microprobe, which provided the first direct comparison of PrP Sc formation and metal ion accumulation. Results showed an accumulation of Fe in cells infected with PrP Sc .

We have investigated the temperature induced denaturation and aggregation of the recombinant fragment SHaPrP90–232 of the hamster prion protein by Fourier transform infrared (FTIR) spectroscopy in H2O and D2O buffers. Difference spectra of this denaturation/aggregation reaction revealed a decrease of α-helical and turn structures and an increase of intermolecularly formed antiparallel β-sheet structure. Compared to previously examined critical oligomers in H2O buffer, the temperature induced aggregates of SHaPrP90–232 exhibited a less rigid but still strong hydrogen bonding pattern as indicated by the β-sheet specific difference band at 1624 cm−1. The denaturation/aggregation temperature of SHaPrP90–232 was consistently determined using the β-sheet specific difference band observed in the H2O or in the D2O experiments. Further, the spectra obtained for the critical oligomers produced in appropriate buffer systems at 25 °C and at 37 °C revealed no significant differences in secondary structure.

Structures of New Bis(pentafluorophenyl)halogeno Mercurates [{Hg(C6F5)2}3(μ-X)]— (X = Cl, Br, I) From the reactions of [PNP]Cl or [PPh4]Y (Y = Br, I) with Hg(C6F5)2 crystals of the composition [Cat][{Hg(C6F5)2}3X] (Cat = PNP, X = Cl (1); Cat = PPh4, X = Br (2), I (3)) are formed. 1 crystallizes in the triclinic space group P1¯, 2 and 3 crystallize isotypically in the monoclinic space group C2/c. In the crystals the halide anions are surrounded by three Hg(C6F5)2 molecules. The reaction of [PPh4]Br with Hg(C6F5)2 under slightly changed conditions gives the compound [PPh4]2[{Hg(C6F5)2}3(μ-Br)][{Hg(C6F5)2}2(μ-Br)] (4).

Colourless single crystals of [Hg(CF3)2(Pur)]4 and [Hg(CF3)2(Dat)]2 were obtained from aqueous and etheric solutions of the respective components Purine, (imidazo[4, 5-d]pyrimidine, Pur), 3, 5-dimethyl-4′-amino-triazole (Dat) and bis(trifluoromethyl)mercury(II), Hg(CF3)2. [Hg(CF3)2(Pur)]4 crystallizes with the tetragonal system (P-4, Z = 8, a = 1486.8(2), c = 1026.2(1) pm, Rall = 0.0657) with tetrameric molecules consisting of four purine molecules bridged by slightly bent Hg(CF3)2 molecules forming a cage with the CF3 ligands surrounding this cage. The two modifications of [Hg(Dat)(CF3)2]2 (I: 170 K, triclinic, P-1, Z = 2, a = 814.9(2), b = 845.4(2), c = 968.4(3) pm, α = 106.55(2)°, β = 103.41(2)°, γ = 110.79(2)°, Rall = 0.1189; II: monoclinic, P21/c, Z = 8, a = 879.8(2), b = 1731.0(3), c = 1593.9(3) pm, β = 106.89(2)°, Rall= 0.1199) both contain dimeric molecules that are stacked parallel to one crystal axis to strands which are arranged in a parallel fashion in I and rotated against each other in II by 110°. In both, the tetrameric [Hg(CF3)2(Pur)]4 and the dimeric [Hg(CF3)2(Dat)]2 the Hg(CF3)2 molecules are slightly bent (around 167 and 170°) and rather weakly attached to the N-donor ligands Pur and Dat with Hg-N distances around 272 pm, although in both cases the Hg atoms bridge between two ligand molecules.

A new convenient synthetic procedure to obtain various 1,1,1,3,3,3-hexafluoro-2-organyl-propan-2-ols and the corresponding trimethylsilyl ethers has been worked out starting from anhydrides or activated esters of carboxylic acids and trimethyl(trifluoromethyl)silane in the presence of tetramethylammonium fluoride. Conditions for the selective formation of 1,1,1,3,3,3-hexafluoro-2-organyl-propan-2-ols as well as the trimethylsilyl derivatives have been found.

Bis(fluorphenyl)quecksilber-Verbindungen, Hg(Rf)2 (Rf = C6F5, C6HF4, C6H2F3, C6H3F2), werden durch Reaktionen von HgF2 mit Me3SiRf in sehr guten Ausbeuten dargestellt. Die Kristallstrukturen von Hg(2, 3, 4, 6-F4C6H)2 (monoklin, P21/n), Hg(2, 3, 5, 6-F4C6H)2 (monoklin, C2/m), Hg(2, 4, 6-F3C6H2)2 (monoklin, P21/c) und Hg(2, 6-F2C6H3)2 (triklin, P1) werden beschrieben. New Syntheses and Crystal Structures of Bis(fluorophenyl) Mercury, Hg(Rf)2 (Rf = C6F5, 2, 3, 4, 6-F4C6H, 2, 3, 5, 6-F4C6H, 2, 4, 6-F3C6H2, 2, 6-F2C6H3) Bis(fluorophenyl) mercury compounds, Hg(Rf)2 (Rf = C6F5, C6HF4, C6H2F3, C6H3F2), are prepared in good yields by the reactions of HgF2 with Me3SiRf. The crystal structures of Hg(2, 3, 4, 6-F4C6H)2 (monoclinic, P21/n), Hg(2, 3, 5, 6-F4C6H)2 (monoclinic, C2/m), Hg(2, 4, 6-F3C6H2)2 (monoclinic, P21/c) and Hg(2, 6-F2C6H3)2 (triclinic, P1) are described.

Ligand exchange reactions of [NMe4]TeCF3 and CuBr, Ag[BF4] and AuCl have been studied in molar ratios of 2:1. While evidence is found for [Cu(TeCF3)2]− moieties by 19F-NMR spectroscopic and mass spectrometric means, [NMe4][Ag(TeCF3)2] and [NMe4][Au(TeCF3)2] were isolated. After cation exchange, the latter compounds were fully characterised as the [PNP] salts ([PNP] = bis(triphenylphosphoranylidene)ammonium). The single crystal structure of [PNP][Au(TeCF3)2] has been elucidated by XRD measurements (P21/a; a = 1765.6(1), b = 1126.0(1), c = 2055.2(1) pm; β = 111.98(1)°; Z = 4).

[NMe 4 ]TeCF 3 is obtained in 60% yield from Me 3 SiCF 3 , elemental tellurium and [NMe 4 ]F in glyme as a pale yellow solid decomposing at 185 °C. Cation exchange with [PNP]Br ([PNP] = bis(triphenylphosphoranylidene)ammonium) and [(dibenzo-18-crown-6)K]Br occurs spontaneously. These low co-ordinating cations increase significantly the nucleophilicity of the anion.

Stopped-flow mixing coupled with time-resolved Fourier transform infrared (FT-IR) spectroscopy represents a new experimental approach to explore protein folding events, which has become possible only recently with the development of appropriate techniques. Here, we discuss experimental apparatus that are capable of initiating and monitoring protein folding processes on the millisecond to minute timescale. The strongest point of the FT-IR approach as a structure-specific probe is that a complete spectrum is available for each time point of measurement. In this way, several spectral windows are accessible simultaneously for the observation of the unfolding or the formation of different secondary structure elements and also events that can be attributed to changes in tertiary structure. One specific advantage of the infrared technique is the ability to monitor directly the kinetics of processes involving beta-sheet structures, which is exceptionally difficult to do with other techniques.