Journal of Chemical Sciences

, Volume 120, Issue 1, pp 187–194 | Cite as

Understanding the folding process of synthetic polymers by small-molecule folding agents

  • S. G. Ramkumar
  • S. RamakrishnanEmail author


Two acceptor containing polyimides PDI and NDI carrying pyromellitic diimide units and 1,4,5,8-naphthalene tetracarboxy diimide units, respectively, along with hexa(oxyethylene) (EO6) segments as linkers, were prepared from the corresponding dianhydrides and diamines. These polyimides were made to fold by interaction with specifically designed folding agents containing a dialkoxynaphtha-lene (DAN) donor linked to a carboxylic acid group. The alkali-metal counter-ion of the donor carboxylic acid upon complexation with the EO6 segment brings the DAN unit in the right location to induce a charge-transfer complex formation with acceptor units in the polymer backbone. This two-point interaction between the folding agent and the polymer backbone leads to a folding of the polymer chain, which was readily monitored by NMR titrations. The effect of various parameters, such as structures of the folding agent and polymer, and the solvent composition, on the folding propensities of the polymer was studied.


Polyimides NMR titration foldamer folding agent 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Hill D J, Mio M J, Prince R B, Hughes T S and Moore J S 2001 Chem. Rev. 101 3893CrossRefGoogle Scholar
  2. 2.
    Appella D H, Christianson L A, Karle I L, Powell D R and Gellman S H 1996 J. Am. Chem. Soc. 118 13071CrossRefGoogle Scholar
  3. 3.
    Licini G, Prins L J and Scrimin P 2005 Eur. J. Org. Chem. 6 969CrossRefGoogle Scholar
  4. 4.
    Gellman S H 2005 Polym. Preprints 46 169Google Scholar
  5. 5.
    Cheng R P 2004 Curr. Opin. Struct. Biol. 14 512CrossRefGoogle Scholar
  6. 6.
    Huc I 2004 Eur. J. Org. Chem. 1 17CrossRefGoogle Scholar
  7. 7.
    Sanford A R and Gong B 2003 Curr. Org. Chem. 7 1649CrossRefGoogle Scholar
  8. 8.
    Gellman S H 1998 Acc. Chem. Res. 31 173CrossRefGoogle Scholar
  9. 9.
    Zych A J and Iverson B L 2000 J. Am. Chem. Soc. 122 8898CrossRefGoogle Scholar
  10. 10.
    Gawronski J, Kaik M, Kwit M and Rychlewska U 2006 Tetrahedron 62 7866CrossRefGoogle Scholar
  11. 11.
    Arunkumar E, Ajayaghosh A and Daub J 2005 J. Am. Chem. Soc. 127 3156CrossRefGoogle Scholar
  12. 12.
    Ajayaghosh A, Arunkumar E and Daub J 2002 Angew. Chem. Intl. Ed. 41 1766CrossRefGoogle Scholar
  13. 13.
    Morozumi T, Hama H and Nakamura H 2006 Anal. Sci. 22 659CrossRefGoogle Scholar
  14. 14.
    Ghosh S and Ramakrishnan S 2004 Angew. Chem. Int. Ed 43 3264CrossRefGoogle Scholar
  15. 15.
    Ghosh S and Ramakrishnan S 2005 Macromolecules 38 676CrossRefGoogle Scholar
  16. 16.
    Ghosh S and Ramakrishnan S 2005 Angew. Chem. Int. Ed. 44 5441CrossRefGoogle Scholar
  17. 17.
    Zhao X, Jia M-X, Jiang X-K, Wu L-Z, Li Z-T and Chen G-J 2004 J. Org. Chem. 69 270CrossRefGoogle Scholar
  18. 18.
    Vögtle F and Weber E 1979 Angew. Chem. Intl. Ed. 18 75CrossRefGoogle Scholar
  19. 19.
    Lohr H G and Vögtle F 1985 Acc. Chem. Res. 18 65CrossRefGoogle Scholar
  20. 21.
    Hynes M J 1993 J. Chem. Soc. Dalt. Trans. 311Google Scholar
  21. 22.
    Deperasinkska I and Prochorow J 1977 Advances in Molecular Relaxation and Interaction Processes 11 51CrossRefGoogle Scholar
  22. 23.
    Sinanoglu O 1968 Molecular associations biology (ed.) B Pullman (New York: Academic Press)Google Scholar

Copyright information

© Indian Academy of Sciences 2008

Authors and Affiliations

  1. 1.Department of Inorganic and Physical ChemistryIndian Institute of ScienceBangaloreIndia

Personalised recommendations