Cover image for Vol. 16 Issue 17

Editor: Greta Heydenrych; Editorial Board Chairs: Christian Amatore, Michael Grätzel, Michel Orrit

Impact Factor: 3.419

ISI Journal Citation Reports © Ranking: 2014: 7/34 (Physics Atomic Molecular & Chemical); 41/139 (Chemistry Physical)

Online ISSN: 1439-7641

Associated Title(s): Advanced Materials, ChemBioChem, ChemCatChem, ChemElectroChem, ChemSusChem, Small

Cover Picture

01/2001The cover picture shows a 22-nucleotide hairpin RNA, the structure of which has been recently been determined by NMR by Rüdisser and Tinoco (J. Mol. Biol. 2000, 295, 1211–1223). The dynamics of the hydrogen bonds (N−H···N) that hold the Watson–Crick base pairs together have been investigated by Chiarparin et al. using multiple-quantum NMR spectroscopy. The existence of scalar couplings across the hydrogen bond between the donor and acceptor nitrogen atoms, discovered by Dingley and Grzesiek (J. Am. Chem. Soc. 1998, 120, 8293–8297), makes it possible to excite zero-, double- and triple-quantum coherences involving the two nitrogen-15 nuclei and the proton that is responsible for the hydrogen bond. These coherences can be represented by suitable density operator terms such as 4N$\rm{_{x}^{1}}$H$\rm{_{{\it z}}^{1}}$N$\rm{_{{\it x}}^{3}}$ that can be converted into characteristic signatures in NMR spectra. Multiple-quantum coherences are exquisitely sensitive to correlated fluctuations of the N−H and H···N dipole–dipole interactions (yellow ellipsoids) and to modulations of the chemical shifts (purple ellipsoids), all of which reflect subtle dynamic effects. Further details are given in the communication by Bodenhausen et al. on pages 41–45.

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