Search results for "Spectroscopy"
showing 10 items of 10293 documents
ChemInform Abstract: Preparation and Structural Characterization of (Me3SiNSN)2Se, a New Synthon for Sulfur-Selenium Nitrides.
2010
The reaction of (Me(3)SiN)(2)S with SeCl(2) (2:1 ratio) in CH(2)Cl(2) at -70 degrees C provides a route to the novel mixed selenium-sulfur-nitrogen compound (Me(3)SiNSN)(2)Se (1). Crystals of 1 are monoclinic and belong the space group P2(1)/c, with a = 7.236(1) A, b = 19.260(4) A, c = 11.436(2) A, beta = 92.05(3) degrees, V = 1592.7(5) A(3), Z = 4, and T = -155(2) degrees C. The NSNSeNSN chain in 1 consists of Se-N single bonds (1.844(3) A) and S=N double bonds (1.521(3)-1.548(3) A) with syn and anti geometry at the N=S=N units. The N-Se-N bond angle is 91.8(1) degrees. The EI mass spectrum shows a molecular ion with good agreement between the observed and calculated isotopic distributions…
Biosilica-based immobilization strategy for label-free OWLS sensors
2013
Abstract In the last years, a new group of enzymes, so-called silicateins, have been identified and characterized, which form the axial filaments of the spicules of the siliceous sponges, consisting of amorphous silica. Silicateins are able to catalyze the polycondensation and deposition of silica at mild conditions (low temperature and physiological pH). By means of these enzymes it is possible for the first time to produce silica nanostructures biocatalytically, which opens new ways for construction of biosensors. The cDNAs encoding the responsible enzymes have been isolated and the proteins can be produced in a recombinant way. Here we demonstrate the silicatein-mediated biosilica format…
Polymorphic and solvate structures of ethyl ester and carboxylic acid derivatives of WIN 61893 analogue and their stability in solution
2014
3-Ethyl ester- (1) and 3-carboxylic acid-isoxazole (2) derivatives of an antiviral drug analogue WIN 61893 were synthesized and characterized by X-ray crystallography and NMR spectroscopy. Crystallization experiments afforded two polymorphic structures for the ethyl ester derivative and two solvate structures for the carboxylic acid derivative based on their ability to form intermolecular hydrogen bonding interactions with the solvent molecules. The conformations of the derivatives depended greatly on the orientation of the planar isoxazole and phenyl-oxadiazole ring systems with respect to one another and were found to take up perpendicular, linear or tilted conformations. The carboxylic a…
Formation, phase composition, and transformations of Langmuir-Blodgett multi- and monolayers containing Fe
1992
Mono- and multilayers of ferric stearate were formed by the Langmuir-Blodgett technique. Thermodesorption of the hydrocarbon chains results in well defined thin oxidic films. Their reduction to Fe2+ and α-Fe was followed by conversion electron Mossbauer spectroscopy. Resonance lines can be observed even if the Fe coverage is less than one monolayer.
The Mössbauer effect and collective motions in glass-forming liquids and polymeric networks
1994
Glass-forming liquids, synthetic polymers and biopolymers share essential properties. Dynamic processes in these complex systems are characterized by cooperative motions with wide distributions of time scales, which manifest themselves in broad quasielastic lines in the Mossbauer spectrum. In this article, the application of the Mossbauer effect to the study of structural dynamics in complex systems is discussed.
Recent advances on application of peptide nucleic acids as a bioreceptor in biosensors development
2019
Abstract The analogs of DNA are unique biomedical tools that are broadly utilized to develop different types of biosensors. Peptide nucleic acids (PNA) are an individual and notable class of nucleic acid analogs due to their unique, novel physicochemical and biochemical characteristics, stability and resistance to nuclease and protease enzymes, significant interactions with complementary strands and remarkable hybridization attributes. Therefore, they are employed in the preparation and fabrication of various types of functional biosensors. In other words, immobilization of PNA as an appropriate diagnostic probe on the surface of electrochemical and optical converters lead to the fabricatio…
Barrier, structural and mechanical properties of bovine gelatin-chitosan blend films related to biopolymer interactions
2014
BACKGROUND The increased use of synthetic packaging films has led to a high ecological problem due to their total non-biodegradability. Thus, there is a vital need to develop renewable and environmentally friendly bio-based polymeric materials. Films and coatings made from polysaccharide polymers, particularly chitosans and gelatins have good gas barrier properties and are envisaged more and more for applications in the biomedical and food fields, as well as for packaging. In this study a casting method was used to develop an edible plasticised film from chitosan and gelatin. Aiming to develop a blend film with enhanced properties, the effects of mixing chitosan (CS) and gelatin (G) in diff…
Omphalotins E-I, Five Oxidatively Modified Nematicidal Cyclopeptides fromOmphalotus olearius
2009
Omphalotins E–I, oxidatively modified cyclic dodecapeptides, were isolated from mycelial extracts of the basidiomycete Omphalotus olearius, and their structures were determined by NMR spectroscopic and MS methods. Four of the five omphalotins contained an unprecedented N-hydroxylated tricyclic tryptophan derivative. All compounds exhibited strong and selective nematicidal activity against the plant pathogen Meloidogyne incognita with LD90 values between 2 and 5 μg mL–1. Cytotoxic activities were not detected up to 50 μg mL–1. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Atmospheric aging and surface degradation in As2S3 fibers in relation with suspended-core profile
2015
Abstract Microstructured optical fibers (MOF) can be seen as next generation fiber of significance in advancing the compact optics because of its excellent compatibility in integrated optics. However, the degradation of their physicochemical properties limits their efficiency and lifetime. Atmospheric moisture is responsible for the degradation of amorphous systems especially chalcogenide glasses. In the light of previously reported studies, in order to clarify the aging process continuously evolving in sulfide microstructured optical fiber over time, a detailed investigation of this phenomenon has been conducted. The time-dependent transmission and glass chemical deterioration have been st…
The triplet excited state of the biocative compound thiabendazole. Characterization and suitability as reporter for cyclodextrin complexation
2012
Fluorescence spectroscopy, laser flash photolysis (LPF), and density functional theory calculations have been performed to characterize the photobehavior of thiabendazole (1). Direct LFP of 1 results in the generation of a transient absorbing at λmax = 570 nm identified as the triplet excited state (31∗). The intersystem crossing quantum yield is 0.91, and the triplet energy is 288 kJ mol−1. The singlet–triplet energy gap is 84 kJ mol−1. The behavior of thiabendazole within CDs results in a marked enhancement of the triplet lifetime, this change is attributed to the mobility restrictions of included 1 imposed by the cyclodextrin cavities.