Search

A series of new adamantyl-oligoethyleneglycol-fullerene hybrids was prepared via Bingel-Hirsch functionalization of the C60 fullerene with various adamantyl-oligoethyleneglycol malonates. As NMDA-targeted antioxidants, these compounds may have the potential to be developed as therapeutic agents for the treatment of neurological disorders. [ABSTRACT FROM AUTHOR]

Abstract: A new type of gas chromatograph mass spectrometer (GC–MS) was used for semi-online monitoring of organic chemical reactions for their yield optimization, mechanism elucidation, and for obtaining information on the reaction products identity and purity. It was used with reaction mixtures without prior separation and purification as needed for NMR, thereby saving time and effort. Our unique GC–MS named 5975-SMB Supersonic GC–MS is based on GC interface with the MS with supersonic molecular beams (SMB) and on ionization of the sample molecules during their axial flight through an open electron ionization ion source as vibrationally cold molecules. GC–MS with SMB is demonstrated to significantly extend the range of compounds amenable for analysis, practically always giving molecular ions, enabling effective fast GC–MS analysis, and providing elemental formulas via isotope abundance analysis with unit mass resolution quadrupole MS. In addition, it uniquely provides uniform response to all compounds, a feature, which is vital for the measurement of chemical reaction yields. In this manuscript, four different organic synthetic reactions were studied and are described. Based on the collected data, we were able to better understand how the reaction conditions should be optimized in order to maximize the yields and purity of target products. Consequently, we propose that GC–MS with SMB can serve as a novel tool for the fast optimization of chemical reactions. [Copyright &y& Elsevier]

The syntheses of 1,10-phenanthroline fluorophore-based chemosensor 7 and its truncated analog 9 are reported. Interactions of these compounds with urea, thiourea, 1,3-dimethylurea, tetrahydropyrimidin-2(1H)-one, imidazolidin-2-one, and selected uronium salts were assessed by three-dimensional excitation-emission spectroscopy, UV-vis absorbance, and fluorescence titrations. Chemosensor 7 was found to be capable of distinguishing between neutral ureas and their salts, by producing a different optical response for each type of compounds. The complexation of urea by 7 was also studied by selective-NOE ¹H NMR, 13C NMR (using 13C-labeled guest), and MALDI-TOF mass spectrometry. In addition, we performed DFT calculations (B3LYP 3-21g** level) for structures of complexes of 7 with urea, imidazolidin-2-one, and tetrahydropyrimidin-2(1H)-one. Development of chemosensor 7-type compounds in conjunction with differential excitation-emission spectroscopy represents an important step toward the development of novel tools for ureas and their salts analysis. [ABSTRACT FROM AUTHOR]