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  • 1
    Electronic Resource
    Electronic Resource
    Application of non-specific fluorescent dyes for monitoring enantio-selective ligand binding to molecularly imprinted polymers (1999)
    Springer
    Fresenius' journal of analytical chemistry 364 (1999), S. 512-516 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The displacement of non-specific dyes from molecularly imprinted polymer (MIP) chromatographic stationary phases has been used for the detection and quantification of ligand-polymer binding events. A blank polymer and an L-phenylalaninamide-imprinted polymer were prepared using methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as a crosslinker. The MIP is first loaded with dye, and a solution of the dye in the eluent is passed through the MIP. If analyte is injected into the dye solution in the eluent, part of the dye is competitively replaced by the analyte from the MIP. Specifically, the competitive displacement of rhodamine B by amino acids and phenylalaninamide (Phe-NH2), respectively, has been studied under polar and hydrophobic elution conditions. Enantioselective binding of Phe and Phe-NH2 to the imprinted polymer was shown to occur in the micromolar concentration range. It is proposed that the displacement of non-specific dyes from MIPs be used for the development of multisensors based upon these highly specific and stable materials, which provide promising alternatives to the use of biological macromolecules in sensor technology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160051377
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  • 2
    Electronic Resource
    Electronic Resource
    Reaktionen mit cyclischen Oxalylverbindungen, 26. Mitt. Cyclokondensation von 4,5-substituierten Thiophen- bzw. N-Alkylpyrrol-2,3-dionen mito-Phenylendiamin (1988)
    Springer
    Monatshefte für Chemie 119 (1988), S. 367-378 
    Details
    ISSN: 1434-4475
    Keywords: 3-Benzoyl-2-phenylthieno[2,3-b]quinoxaline ; 1-Alkyl-5,10-dihydro-4,10a-diphenyl-pyrrolidino[2,3-b][1,5]-benzodiazepin-2,3-dione ; X-ray structure analysis ; 13C NMR spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract 4-Benzoyl-5-phenylthiophene-2,3-dione (1) reacts witho-phenylendiamine to give the quinoxaline derivative2 which cyclizes either to the furo[2,3-b]quinoxaline4 or to the thieno[2,3-b]quinoxaline5 depending on the reaction conditions. On the other hand, the pyrrol-2,3-diones6 ando-phenylendiamine combine yielding the pyrrolidino[2,3-b][1,5]benzodiazepine derivatives7. The structures of all compounds were confirmed by IR and13C NMR spectroscopic measurements based on X-ray structure determinations of4/5 (mixed crystal) as well as7 b.4/5 crystallize triclinically in the space group P1 (Nr. 2) with two molecules per cell, while7 b crystallizes monoclinically in space group P21/a (Nr. 14) with four molecules7 b and four moleculesDMSO per cell. The reaction pathways leading to the compounds2,4,5, and7 are briefly discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00810263
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  • 3
    Electronic Resource
    Electronic Resource
    An investigation of squaraines as a new class of fluorophores with long-wavelength excitation and emission (1993)
    Springer
    Journal of fluorescence 3 (1993), S. 153-155 
    Details
    ISSN: 1573-4994
    Keywords: Fluorescence sensing ; squaraines ; phase-modulation fluorometry ; red fluorescence ; near-infrared fluorescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present an overview of our investigation of the spectral properties and photostabilities of squaraine derivatives. The objective was to identify long-wavelength probes with reasonable quantum yields, reasonably long lifetimes, and good photostabilities for use in fluorescence-based assays and/or imaging. Both symmetrical and unsymmetrical squaraines were studied. Based on this investigation the most suitable probes for use in a biological application were found to be the symmetrical indolenine derivatives of the squaraines, which display the highest photostability. Importantly, their quantum yields and lifetimes increase significantly upon covalent and noncovalent binding to proteins (bovine serum albumin, antibodies), demonstrating the usefulness of the squaraines as long wavelength probes. The squaraine absorbance maxima between 630 and 650 nm allows the use of the new commercially available 635- and 650-nm diode lasers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00862734
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  • 4
    Electronic Resource
    Electronic Resource
    Reactions of cyclic oxalyl compounds, 37. Substituent effects on the site of nucleophilic attack at 1H-pyrrole-2,3-dionesDedicated to Professor Josef Schurz on the occasion of his 70th birthday. (1995)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 537-543 
    Details
    ISSN: 0947-3440
    Keywords: Pyrrole-2,3-diones ; Nucleophilic addition ; Substituent effects ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of 1H-pyrrole-2,3-diones 2a-i with N- and O-nucleophiles proceed by initial attack at C-2 or/and C-5. Consequently, earlier results suggesting structures of type A (attack at C-3) have to be revised (5, 13, 17, 18b). In general, electron-withdrawing substituents at C-4 favor attack at C-5 with formation of 2-pyrrolones 5, 6, 10, 13, 17, and 20. Alternatively, attack at C-2 leads to α-oxobutenoic acid derivatives 3, 7, 11, 12, 15, and 18. IR and 13C-NMR spectroscopic techniques were employed to differentiate between the possible isomeric addition products formed. The structure of methyl α-oxobutenoate 15 was established by an X-ray crystallo-graphic analysis.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199519950373
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