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Cover Picture: Chem. Eur. J. 23/2002
Author(s) -
Ahn DaeRo,
Egger Anita,
Lehmann Christian,
Pitsch Stefan,
Leumann Christian J.
Publication year - 2002
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Reports
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20021202)8:23<5275::aid-chem5275>3.0.co;2-z
Subject(s) - nucleobase , amide , chemistry , stereochemistry , pairing , duplex (building) , bicyclic molecule , crystallography , hydrogen bond , base pair , dna , molecule , physics , biochemistry , superconductivity , organic chemistry , quantum mechanics
The cover picture shows the mirror‐image CD spectral relationship rationalized by building molecular models of right‐ and left‐handed nucleic acid duplex structures. In the remarkable bicyclo[3.2.1]amide–DNA constitution, a conformational switch of the amide relay group linking the backbone and nucleobase allows right‐ as well as left‐handed helical base pairing, depending on the complementary duplex strand. The respective conformations are related to antipodal carbonyl interlocking between the rigid bicyclic unit, assisted by interresidual axially chiral intrastrand hydrogen bonding through the amide functional groups. A right‐handed helix is maintained for the heteroduplex with oligonucleotides of natural chirality, whereas the mirror‐image left‐handed spectrum is observed for pairing with enantiomeric RNA as well as with the duplex uniquely composed of bicyclo[3.2.1]amide nucleotides. This is discussed in more detail by C. J. Leumann et al. on p. 5312 ff. (Illustration provided by C. Lehmann, University of Lausanne)