Novel lithocholaphanes: Syntheses, NMR, MS, and molecular modeling studiesстатья
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Дата последнего поиска статьи во внешних источниках: 14 сентября 2013 г.
Аннотация:Novel head-to-head lithocholaphanes 6 and 11 have been synthesized via precursors 1-5 and 7-10 with overall good yields, and characterized by H-1, C-13, and N-15 NMR spectroscopy, ESI-TOF mass spectrometry, thermal analysis, and molecular modeling. In addition, the binding abilities of 6 and 11 towards alkali metal cations have been investigated via competitive complexation studies using equimolar mixtures of Li+, Na+, K+, and Rb+-cations, and cholaphanes 6 and 11. The formation of cation-cholaphane adducts was detected by ESI-TOF mass spectrometry. The trends in these comparative binding studies are nicely reproduced theoretically with PM3 energetically optimized structures of 6 and 11 and their interaction energies with alkali metal cations calculated by molecular mechanics. Cholaphane 11 possessing a peptoid type structural fragment, -(CH2CONHCH2CH2)(2)O-, as a coordination sphere, shows binding tendency towards lithium and sodium cations, whereas 6 possessing an ester type, -(CH2OCOCH2)(2)O- moiety and a bigger cavity size than 11, shows merely a tendency towards bigger alkali metal cations, potassium and rubidium. (c) 2007 Elsevier B.V. All rights reserved.