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Matthew Curtis Mikael A. Minier Priyanka Chitranshi O. David Sparkman Patrick R. Jones Liang Xue 《Journal of the American Society for Mass Spectrometry》2010,21(8):1371-1381
Direct analysis in real time (DART) mass spectrometry is a recently developed innovative technology, which has shown broad
applications for fast and convenient analysis of complex samples. Due to the ease of sample preparation, we have recently
initiated an investigation of the feasibility of detecting nucleotides and nucleosides using the DART-AccuTOF instrument,
which we will refer to as the DART mass spectrometer. Our experimental results reveal that the ions representing the intact
molecules of nucleotides are not detectable in either positive-ion or negative-ion mode. Instead, all four natural nucleotides
fragment in the DART ion source, and a common fragment ion, [C5H5O]+ (1), is observed, which is probably formed via multiple-elimination reactions. Interestingly, 1 can form adducts with nucleobases
in different molar ratios in the DART ion source. In contrast to nucleotides, the ions representing the intact molecules of
nucleosides are detected in both positive-ion and negative-ion mode using DART mass spectrometry. Surprisingly, the fragmentation
pattern of nucleosides is different from that of nucleotides in the DART ion source. In the cases of nucleosides (under positive-ion
conditions), the production of 1 is not observed, indicating that the phosphate group plays an important role for the multiple
eliminations observed in the spectra of nucleotides. The in-source reactions described in the present work show the complexity
of the conditions in the DART ion source, and we hope that our results illustrate a better understanding about DART mass spectrometry. 相似文献
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Sangya Chitranshi Dr. B. Adinarayana Mainak Das Dr. Won-Young Cha Prof. Dr. Dongho Kim Prof. Dr. A. Srinivasan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(56):12911-12915
Three distinct conformational structures of carbaoctaphyrins were prepared by incorporating bis-4,4'-biphenyl units in the macrocyclic core. The free-base form adopts a figure-eight conformation, whereas the protonation triggers a conformational change with a pyrrole ring inversion and acquires an open-framework structure. The insertion of bis-RhI metal ion in the macrocyclic core affords a singly twisted conformational structure. Furthermore, the local aromaticity in the bis-4,4'-biphenyl ring dominates the overall macrocyclic aromaticity in all three forms, and thus adopts nonaromatic characteristics. These results are supported by spectral as well as theoretical studies, and they are unambiguously confirmed by X-ray crystal analyses. 相似文献
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