Protonation-induced transition between two distinct helical conformations of a synthetic oligomer via a linear intermediate

Angewandte Chemie - International Edition

Volumn 42, Issue 24, 2003, Pages 2738-2740

  Dolain, Christel ^a   Maurizot, Victor ^a   Huc, Ivan ^a  

^a INSTITUT EUROPÉEN DE CHIMIE ET BIOLOGIE   (France)

Author keywords

Chirality; Conformation analysis; Helical structures; Hydrogen bonds; Supramolecular chemistry

Indexed keywords

CONFORMATIONS; MOLECULES; SYNTHESIS (CHEMICAL);

PROTONATION;

OLIGOMERS;

OLIGOMER;

ARTICLE; CONFORMATIONAL TRANSITION; PH; PROTON TRANSPORT; STRUCTURE ANALYSIS; SUPRAMOLECULAR CHEMISTRY;

EID: 0037715341     PISSN: 14337851     EISSN: None     Source Type: Journal    
DOI: 10.1002/anie.200351080     Document Type: Article

References (24)

1. J.-M. Lehn, Supramolecular Chemistry-Concepts and Perspectives, VCH, Weinheim, 1995.
2. Special Issue on Molecular Machines (Ed.: J. F. Stoddart), Acc. Chem. Res. 2001, 34, 409;
3. V. Balzani, F. Credi, M. Raymo, J. F. Stoddart, Angew. Chem. 2000, 112, 3484;
4. Angew. Chem. Int. Ed. 2000, 39, 3348.
5. For related examples of unfolding of bent or helical conformers: P. S. Corbin, S. C. Zimmermann, J. Am. Chem. Soc. 2000, 122, 3779;
6. M. Barboiu, J.-M. Lehn, Proc. Natl. Acad. Sci. USA 2002, 99, 5201;
7. H. Nakako, R. Nomura, T. Masuda, Macromolecules 2001, 34, 1496;
8. M. Fujiki, J. Am. Chem. Soc. 2000, 122, 3336;
9. J. Lie, G. B. Schuster, K.-P. Cheon, M. M. Green, J. V. Selinger, J. Am. Chem. Soc. 2000, 122, 2603.
10. For a recent and extensive review on the folding properties of synthetic molecular strands see: D. J. Hill, M. J. Mio, R. B. Prince, T. S. Hughes, J. S. Moore, Chem. Rev. 2001, 101, 3893.
11. N. C. Singha, D. N. Sathyanarayana, J. Mol. Struct. 1997, 403, 123;
12. V. Berl, I. Huc, R. G. Khoury, J.-M. Lehn, Chem. Eur. J. 2001, 7, 2798;
13. I. Huc, V. Maurizot, H. Gornitzka, J.-M. Léger, J. Chem. Soc. Chem. Commun. 2002, 578.
14. For related systems see: B. Gong, Chem. Eur. J. 2001, 7, 4337, and references therein;
15. Y. Hamuro, S. J. Geib, A. D. Hamilton, J. Am. Chem. Soc. 1997, 119, 10587.
16. See supporting information.
17. S. J. Geib, S. C. Hirst, C. Vicent, A. D. Hamilton, J. Chem. Soc. Chem. Commun. 1991, 197;
18. R. P. Dixon, S. J. Geib., A.D. Hamilton, J. Am. Chem. Soc. 1992, 114, 365;
19. R. Ostaszewski, Z. Urbanczyk-Lipkowska, J. Mol. Struct. 1999, 474, 197.
20. 3 and MsOH, and cosolvents interfere with the protonation.
21. Protonation also causes the dissociation of the double helices formed by these oligomers, see: V. Berl, I. Huc, R. G. Khoury, M. J. Krische, J.-M. Lehn, Nature 2000, 407, 720;
22. V. Berl, I. Huc, R. G. Khoury, J.-M. Lehn, Chem. Eur. J. 2001, 7, 2810.
23. The assignment is based on the comparison of this spectrum to the spectra of shorter oligomers, and on the integration and the values of the chemical shifts of these signals: the signals at higher field belong to the pyridinedicarbonyl units, and the signals at lower field belong to the diaminopyridine units; the less deshielded and broader signal at δ = 14.9 ppm is assigned to the terminal pyridinium unit, which can form a hydrogen bond with only one carbonyl group.
24. The band induced in the pyridinium chromophores becomes faint at very high TfOH concentration (above 30 equiv) or in the presence of MeOH, presumably because of a weaker induction in protic medium.