Concentrations of 20 perfluorinated alkyl substances (PFASs) were measured in dust samples from 41 homes in Canada, the Czech Republic, and United States in the spring-summer of 2013. The most frequently detected compounds were perfluorohexanoic acid (PFHxA) and perfluorooctane sulfonate (PFOS). PFOS and perfluorooctanoic acid (PFOA) had the highest concentrations of PFASs in all countries. PFOS median concentrations for the three countries were between 9.1 and 14.1ng/g, and PFOA medians ranged between 8.2 and 9.3ng/g. In general, concentrations in North America were higher than in the Czech Republic, which is consistent with usage patterns. No differences were found for perfluorooctane sulfonamides/sulfonamidoethanols (FOSA/Es) levels due to the low number of detections. Homologue profiles suggest that the shift from longer to shorter chain PFASs is more advanced in North America than in Europe. Significant relationships were found among individual homologues and between PFAS concentrations in dust and type of floor, number of people living in the house, and building age.

• Klíčová slova
• House dust *, Indoor environment *, PFASs *, Perfluorinated compounds *,
• MeSH
• bydlení * MeSH
• dospělí MeSH
• fluorokarbony analýza   MeSH
• kyseliny alkansulfonové analýza   MeSH
• látky znečišťující životní prostředí analýza   MeSH
• lidé MeSH
• monitorování životního prostředí MeSH
• prach analýza   MeSH
• předškolní dítě MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• předškolní dítě MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Česká republika MeSH
• Kanada MeSH
• Spojené státy americké MeSH
• Názvy látek
• fluorokarbony MeSH
• kyseliny alkansulfonové MeSH
• látky znečišťující životní prostředí MeSH
• prach MeSH

Alkylation of the [nido-5,6-R12C2B8H9]- anions (where R1 = H and Me) with alkyl halides (RX, where R = primary and secondary alkyls) in boiling tetrahydrofuran (THF) proceeds via unusual H2 elimination, followed by cage closure to give a series of the neutral closo-1,2-R12C2B8H7-3-R derivatives in ∼70-80% yields. In contrast, treatment of the unsubstituted [nido-5,6-C2B8H11]- anion with tert-butyl bromide (t-BuBr) led to the formation of the parent closo-1,2-C2B8H10 in >85% yield. The constitution of all compounds isolated has been confirmed unambiguously by multinuclear (11B, 1H, and 13C) nuclear magnetic resonance measurements and α-shift correlation assessments.

• Publikační typ
• časopisecké články MeSH

Ionic liquids (ILs) have become nearly ubiquitous solvents and their interactions with biomolecules has been a focus of study. Here, we used the fluorescence emission of DAPI, a groove binding fluorophore, coupled with molecular dynamics (MD) simulations to report on interactions between imidazolium chloride ([Imn,1]+) ionic liquids and a synthetic DNA oligonucleotide composed entirely of T/A bases (7(TA)) to elucidate the effects ILs on a model DNA duplex. Spectral shifts on the order of 500-1000 cm-1, spectral broadening (~1000 cm-1), and excitation and emission intensity ratio changes combine to give evidence of an increased DAPI environment heterogeneity on added IL. Fluorescence lifetimes for DAPI/IL solutions yielded two time constants 0.15 ns (~80% to 60% contribution) and 2.36-2.71 ns for IL up to 250 mM. With DNA, three time constants were required that varied with added IL (0.33-0.15 ns (1-58% contribution), ~1.7-1.0 ns (~5% contribution), and 3.8-3.6 ns (94-39% contribution)). MD radial distribution functions revealed that π-π stacking interactions between the imidazolium ring were dominant at lower IL concentration and that electrostatic and hydrophobic interactions become more prominent as IL concentration increased. Alkyl chain alignment with DNA and IL-IL interactions also varied with IL. Collectively, our data showed that, at low IL concentration, IL was primarily bound to the DNA minor groove and with increased IL concentration the phosphate regions and major groove binding sites were also important contributors to the complete set of IL-DNA duplex interactions.

• Klíčová slova
• DAPI, DNA duplex, DNA oligonucleotide, fluorescence, fluorescence lifetime, imidazolium ionic liquids, molecular dynamics, radial distribution function,
• MeSH
• DNA chemie   MeSH
• imidazoly chemie   MeSH
• iontové kapaliny chemie   MeSH
• oligonukleotidy chemie   MeSH
• simulace molekulární dynamiky * MeSH
• termodynamika MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• DNA MeSH
• imidazole MeSH Prohlížeč
• imidazoly MeSH
• iontové kapaliny MeSH
• oligonukleotidy MeSH

This review summarizes achievements in the synthesis of 1,2-disubstituted adamantane derivatives by the construction of the tricyclic framework either by total synthesis or by ring expansion/contraction reactions of corresponding adamantane homologues. It is intended to complement reviews focusing on the preparation of 1,2-disubstituted derivatives by C-H functionalization methods.

• Klíčová slova
• adamantane, alkyl shifts, diamondoids, homoadamantane, noradamantane, protoadamantane, rearrangement, ring contraction, ring expansion, total synthesis,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

A series of stable organosuperbases, N-alkyl- and N-aryl-1,3-dialkyl-4,5-dimethylimidazol-2-ylidene amines, were efficiently synthesized from N,N'-dialkylthioureas and 3-hydroxy-2-butanone and their basicities were measured in acetonitrile. The derivatives with tert-alkyl groups on the imino nitrogen were found to be more basic than the tBuP(1) (pyrr) phosphazene base in acetonitrile. The origin of the high basicity of these compounds is discussed. In acetonitrile and in the gas phase, the basicity of the alkylimino derivatives depends on the size of the substituent at the imino group, which influences the degree of aromatization of the imidazole ring, as measured by (13)C NMR chemical shifts or by the calculated ΔNICS(1) aromaticity parameters, as well as on solvation effects. If a wider range of imino-substituents, including electron-acceptor substituents, is treated in the analysis then the influence of aromatization is less predominant and the gas-phase basicity becomes more dependent on the field-inductive effect, polarizability, and resonance effects of the substituent.

• Publikační typ
• časopisecké články MeSH

Thermoresponsive nanoparticles based on the interaction of metallacarboranes, bulky chaotropic and surface-active anions, and poly(2-alkyl-2-oxazoline) block copolymers were prepared. Recently, the great potential of metallacarboranes have been recognized in biomedicine and many delivery nanosystems have been proposed. However, none of them are thermoresponsive. Therefore, a thermoresponsive block copolymer, poly(2-methyl-2-oxazoline)-block-poly(2-n-propyl-2-oxazoline) (PMeOx-PPrOx), was synthesized to encapsulate metallacarboranes. Light scattering, NMR spectroscopy, isothermal titration calorimetry, and cryogenic TEM were used to characterize all solutions of the formed nanoparticles. The cloud-point temperature (TCP ) of the block copolymer was observed at 30 °C and polymeric micelles formed above this temperature. Cobalt bis(dicarbollide) anion (COSAN) interacts with both polymeric segments. Depending on the COSAN concentration, this affinity influenced the phase transition of the thermoresponsive PPrOx block. The TCP shifted to lower values at a lower COSAN content. At higher COSAN concentrations, the hybrid nanoparticles are fragmented into relatively small pieces. This system is also thermoresponsive, whereby an increase in temperature leads to higher polymer mobility and COSAN release.

• Klíčová slova
• anions, chaotropic agents, metallacarboranes, micelles, polymers,
• Publikační typ
• časopisecké články MeSH

Reactions between closo-1,2-C(2)B(8)H(10) (1) and amines of general formulation R(1)R(2)NH (where R(1), R(2) = H, H; Me, H; t-Bu, H and Et, Et) resulted in a straightforward cluster expansion and formation of the 11-vertex arachno-azadicarbaboranes of the 1,1-R(1),R(2-)1,6,9-NC(2)B(8)H(11) (2) cluster constitution (where R(1), R(2) = H, H 2a; Me, H 2b; t-Bu, H 2c and Et, Et 2d) in yields 10-75%, depending on the nature of the amine used. The reactions are the first example of a direct closo to arachno transformation in the area of cluster-boron compounds. Compounds 2b and 2c were isolated in two isomeric forms anti- and syn- that differ in the positioning of the t-Bu substituent with respect to the bridging hydrogen site. Deprotonation of compounds 2 generally leads to removal of the bridging proton and formation of the [1,1-R(1),R(2-)1,6,9-NC(2)B(8)H(11)](-) (2-) anions that, in the case of the monoalkylated Me and t-Bu derivatives, adopt only an anti configuration. The structure of anti-2c was determined by X-ray diffraction analysis and the geometries of the parent compound and the corresponding syn and anti isomers were optimised at the RMP2/6-31G* level. The composition of all compounds is consistent with the results of mass spectrometry and multinuclear ((1)H and (11)B) spectroscopy complemented by two-dimensional [(11)B-(11)B]-COSY and (1)H{(11)B(selective)} NMR measurements. Experimental (11)B chemical shifts generally show acceptable agreement with theoretical values calculated by GIAO methods, in particular at GIAO-MP2/II, where possible.

• Publikační typ
• časopisecké články MeSH

Alterations in oligosaccharides and types of sialic acid (SA) attachments have been associated with different pathological states. Matrix-assisted laser desorption mass spectrometry (MS) is commonly used for glycosylation studies. However, native sialylated glycans are suppressed or not detected during MS experiments. Consequently, different approaches have been employed to neutralize the negative charge of the carboxyl group. In this study, we present the advantage of phenylhydrazine (PHN) labeling for the detection and efficient discrimination of SA linkages when this derivatization follows alkyl esterification. As expected, PHN-labeled sialylated oligosaccharides with the 2,6-linkage type can be easily recognized according to the additional shift in mass corresponding to the presence of a methyl or ethyl group. Surprisingly, oligosaccharides with the 2,3-linked SA residue instead of a lactone were detected carrying the second PHN unit. This was beneficial as no further processing after esterification was needed to stabilize the lactone form. Moreover, during tandem mass experiments, all modified glycans produced favorable fragmentation patterns with a coherent recognition of SA linkages. Although both types of esterification, herein called the EST-PHN approach, provided comparable results, methylation exhibited marginally higher linkage specificity than ethyl esterification. The simplicity and effectiveness of the methodology are demonstrated on the model compound, sialyllactose, and its applicability for biological studies is presented on N-glycan profiling in the sera of lung cancer patients.

• MeSH
• esterifikace MeSH
• fenylhydraziny chemie   MeSH
• kyselina N-acetylneuraminová chemie   MeSH
• laktony MeSH
• lidé MeSH
• nádory plic * diagnóza   MeSH
• oligosacharidy * chemie   MeSH
• polysacharidy chemie   MeSH
• spektrometrie hmotnostní - ionizace laserem za účasti matrice metody   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• fenylhydraziny MeSH
• kyselina N-acetylneuraminová MeSH
• laktony MeSH
• oligosacharidy * MeSH
• polysacharidy MeSH

In this study, we have investigated the supramolecular interaction between series of 1-alkyl-3-methylimidazolium guests with variable alkyl substituent lengths and cucurbit[6]uril (CB6) in the solution and the solid state. Correct interpretation of (1)H NMR spectra was a key issue for determining the binding modes of the complexes in solution. Unusual chemical shifts of some protons in the (1)H NMR spectra were explained by the polarization of the imidazolium aromatic ring upon the complexation with the host. The formation of 1:1 complex between 1-ethyl-3-methylimidazolium and CB6 is in disagreement with previously reported findings describing an inclusion of two guest molecules in the CB6 cavity.

• MeSH
• elektrony MeSH
• imidazoly chemie   MeSH
• iontové kapaliny chemie   MeSH
• magnetická rezonanční spektroskopie MeSH
• molekulární modely MeSH
• přemostěné cyklické sloučeniny chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• cucurbit(6)uril MeSH Prohlížeč
• imidazoly MeSH
• iontové kapaliny MeSH
• přemostěné cyklické sloučeniny MeSH

Little information exists on the effects of shipping and handling on per- and polyfluoroalkyl substances (PFASs) in environmental samples. Thus, we evaluated the integrity of dried wastewater extracts and the sensitivity of our high-resolution mass spectrometry (HRMS) instrument to perform such analyses by monitoring 13 representative PFASs in samples extracted, evaporated, and stored at room temperature up to one month. Relative to zero-day recoveries of six detected PFASs ranged between 94 and 124% (RSD <38%) for influents, between 88 and 126% (RSD <18%) for effluents after 28 days. Larger variabilities are tentatively associated with the lack of specific mass-labeled standards and the interactions between analytes and remaining matrix components over time. In a second stage, a mix of local and international dry-shipped wastewater samples were analyzed and the same PFASs were quantified. Up to six PFASs were identified, with median concentrations ranging from 1.3 (perfluoro butyl sulfonate (PFBS)) to 7.7 ng/L (perfluoro hexanoic acid (PFHxA)) and from 1.5 (PFBS) to 13.8 ng/L (PFHxA) in local influents and effluents respectively; and from 0.7 (perfluoro hexyl sulfonate (PFHxS)) to 52.8 ng/L (PFHxA) and from 0.5 (PFHxS) to 21.4 ng/L (PFHxA) in Greek influents and effluents, respectively. The importance of this study lies on the need to consider the wider recovery shifts and expanded variability ranges of PFASs derived from the transport and storage times of dried extracts, particularly when applied to HRMS and wide-scope screening approaches.

• Klíčová slova
• Full-scan acquisition, Integrity, Occurrence, PFAS, TOF, WWTP,
• MeSH
• alkylsulfonany MeSH
• chemické látky znečišťující vodu * analýza   MeSH
• fluorokarbony * analýza   MeSH
• kyseliny alkansulfonové * MeSH
• monitorování životního prostředí MeSH
• odpadní voda MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• alkylsulfonany MeSH
• chemické látky znečišťující vodu * MeSH
• fluorokarbony * MeSH
• kyseliny alkansulfonové * MeSH
• odpadní voda MeSH