Overtone spectra of 2-mercaptoethanol and 1,2-ethanedithiol

Vibrational spectra of vapor-phase 1,2-ethanedithiol and 2-mercaptoethanol were recorded to investigate weak intramolecular interactions. The spectra were recorded with conventional absorption spectroscopy and laser photoacoustic spectroscopy in the 2000-11,000 cm(-1) region. The room temperature spectra of each molecule are complicated by contributions from several conformers. Anharmonic oscillator local-mode calculations of the OH- and SH-stretching transitions have been performed to facilitate assignment of the different conformers in the spectra. We observe evidence of hydrogen-bond-like interactions from OH to S, but not from SH to O or S. The OH to S intramolecular interaction in 2-mercaptoethanol is weak and comparable to that found in the OH to O interaction in ethylene glycol.     

Application of the QuEChERS method for the analysis of pyrethrins and pyrethroids in fish tissues

The application of the quick easy cheap effective rugged and safe (QuEChERS) method has generally been used in the preparation of produce samples (e.g., lettuce and oranges) for pesticide analysis. In the present study, the QuEChERS method was successfully applied to the determination of the natural pyrethrins (cinerin I and II, jasmolin I and II, and pyrethrin I and II), as well as two pyrethroid insecticides, cypermethrin and deltamethrin, in fin and non-fin fish products. Analysis of these compounds was performed using gas chromatography–mass spectrometry. Although cypermethrin is not and has not been registered for pest control use in aquaculture operations in Canada, cypermethrin was detected in domestically produced salmon. Cypermethrin was detected in seven of the 18 Canadian farmed salmon samples (39%), although it was not detected in any wild domestic salmon (n = 3). Cypermethrin concentrations ranged from 0.3 to 6.5 ng/g in the positive samples. It was not, however, observed in any imported fish product or any other domestically produced fish product.     

Solid-state NMR investigation of sodium nucleotide complexes

Solid-state NMR has been used to analyze the chemical environments of sodium sites in powdered crystalline samples of sodium nucleotide complexes. Three of the studied complexes have been previously characterized structurally by crystallography (disodium deoxycytidine-5'-monophosphate heptahydrate, disodium deoxyuridine-5'-monophosphate pentahydrate and disodium adensoine-5'-triphosphate trihydrate). For these salts, the nuclear quadrupole coupling parameters measured by (23)Na multiple-quantum magic-angle-spinning NMR could be readily correlated with sodium ion coordination environments. Furthermore, two complexes that had not been previously characterized structurally, disodium uridine-3'-monophosphate and a disodium uridine-3'-monophosphate/disodium uridine-2'-monophosphate mix, were identified by solid-state NMR. A spectroscopic assignment of the four sites of an additional salt, disodium adensoine-5'-triphosphate trihydrate, is also presented and discussed within the context of creating a general approach for the spectroscopic assignment of multiple sites in sodium nucleotide complexes.     

Light-emitting iridium(III) and ruthenium(II) polypyridyl complexes containing quadruple hydrogen-bonding moieties

A novel compound containing both a 2,2'-bipyridine as well as a 2-ureido-4[1H]-ureidopyrimidinone supramolecular moiety (3) has been synthesised and fully characterized by 1H-NMR, MALDI-TOFMS, UV-vis and IR spectroscopy. Subsequent coordination to iridium and ruthenium polypyridyl precursors allowed the formation of iridium(III) and ruthenium(II) polypyridyl dimers (5 and 7) assembled via quadruple hydrogen-bonding as well as metal coordination interactions. The syntheses and complete characterization of these materials by means of two-dimensional NMR techniques (1H-1H COSY and 1H-1H DOSY) as well as IR and MALDI-TOFMS are described in detail. Comparative studies of the optical properties of the luminescent model complexes (5' and '7) and the dimer species (5 and 7) are also illustrated. In addition, good processability of the materials has been demonstrated by inkjet printing leading to thin films revealing their potential for light-emitting devices.     

Scalable synthesis of an integrin-binding peptide mimetic for biomedical applications

A scalable, solution-phase synthesis of the selectively protected non-peptide RGD (arginine-glycine-aspartic acid) mimetic 6 is described. This synthesis serves as an alternative to the previously described solid-phase synthesis of this compound, thereby making this important integrin-binding mimetic readily accessible. The free carboxylic acid of 6 was conjugated to a protected diamine, followed by global deprotection to give a derivative 27, suitable for immobilization onto amine-reactive surfaces. The RGD mimetic 28 demonstrated superior biological activity in comparison to a native linear RGD peptide and the semi-synthetic cyclic cRGDfK peptide in a cell attachment inhibition assay.     

Anomalous infrared spectra of diazepam in potassium bromide pellets prepared from chloroform solutions

When diazepam in chloroform was incorporated into a KBr pellet, its infrared (i.r.) spectrum showed an anomalous spectral phenomenon at 836 cm^?1. Examination of i.r. spectra of diazepam obtained by the solution, multiple-internal-reflectance, and KBr-pellet techniques suggest that this spectral characteristic is due to the orientation effect of diazepam in KBr pellets.     

Coupling micelle-mediated extraction using mixtures of surfactants and fluorescence measurements with a fiber-optic for the screening of PAHs in seawater

The screening of PAHs from seawater samples using cloud-point extraction (CPE) as a step prior to their determination by fluorescence measurements with a fiber-optic is proposed. The CPE is carried out with the nonionic surfactants mixture POLE and Brij 30. The fluorescence measurement parameters were optimized, allowing selection of benzo(a)pyrene (B(a)Py) and benzo(k)fluoranthene (B(k)Ft) as the target analytes for the screening. The reproducibility of the whole screening system, expressed as relative standard deviation, was 9.0% for B(a)Py and 12.1% for B(k)Ft (both for n = 7). The reliability of the method was established at five concentrations for B(a)Py (between 0.5 and 3.3 times the detection limit: 0.31 ng ml(-1)) and at three concentrations for B(k)Ft (between 0.6 and 2.5 times the detection limit: 0.56 ng ml(-1)). The resolution of binary mixtures of these PAHs at different levels of concentration, and a study of the interferences with the rest of the PAHs were also carried out.     

Number 75

Reviews are listed in order of appearance in the sources indicated. In multidisciplinary review journals, only those reviews which fall within the scope of this Journal are included. Sources are listed alphabetically in three categories: regularly issued review journals and series volumes, contributed volumes, and other monographs. Titles are numbered serially, and these numbers are used for reference in the index. Major English-language sources of critical reviews are covered. Encyclopedic treatises, annual surveys such as Specialist Periodical Reports, and compilations of symposia proceedings are omitted. This installment of Recent Reviews covers principally the middle part of the 2004 literature. Previous installment: J. Org. Chem. 2004, 69(20), 6957-66.     

Thermal and mechanical characterization of plasticized poly (L-lactide-co-D,L-lactide) films for food packaging

In this work amorphous poly(L-lactide-co-D,L-lactide) (PLLA/PDLLA) was blended with four different commercial adipates to obtain films with enhanced mechanical and thermal properties. Efficiency of plasticizers was evaluated by studying their compatibility with the polymer and their effect on its glass transition temperature. All plasticizers were compatible with the matrix up to a critical composition depending on its molar mass. The addition of plasticizers caused a decrease in elastic modulus and tensile stress, meanwhile elongation at break had a maximum increase for polyadipates with the lower molar mass. Monomeric adipate showed some migration at concentration higher than 10 mass%, while the addition of the higher molar mass plasticizer lead to eventual phase separation. Polyadipates with low molar mass showed a promising behaviour to overcome the brittleness in PLLA/PDLLA films.