Skip to main content
SpringerLink
Log in

β-Cyclodextrin Inclusion Complexes of 2-Hydroxyfluorene and 2-Hydroxy-9-fluorenone: Differences in Stoichiometry and Excited State Prototropic Equilibrium

  • Published:
Journal of Solution Chemistry Aims and scope Submit manuscript

Abstract

We report that 1:1 and 1:2 complexes are formed for 2-hydroxy-9-fluorenone with β-cyclodextrin (β-CD) and that there is an unusual red shift in emission at higher concentrations of β-CD. Between different stoichiometries of the complexes the titrimetric curves for the neutral–anionic equilibria for the guests differ drastically and so do the excited state pK values. The formation of an 1:1 inclusion complex with 2-hydroxy-9-fluorenone (2HFN) as the guest in β-CD with the binding constant (K) of 606.65 L·mol−1 was determined. The ground and excited state pK a values for the neutral–mono-anion equilibrium are not affected by β-CD. Hence the hydroxyl group is considered exposed in the aqueous environment. Two different types of inclusion complexes of 2HFN were observed in β-CD. The 1:2 complex of 2HFN shows a red shift from the 1:1 complex and is less fluorescent that the 1:1 complex. The red shift reveals that the 1:2 complex is more stabilized than the 1:1 complex. The excited state pK a values in both complexes with β-CD are higher that those in aqueous solution. This shows that the complexation makes the molecule less acidic in the S1 state. The β-CD molecule is perceived as not able to encapsulate the 2HFN molecule fully, but the larger rim of the β-CD comes closer to the C=O group. The other half of the 2HFN molecule is encapsulated by the second β-CD molecule and thus there is formation of the 1:2 inclusion complex at higher concentrations of β-CD.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9
Fig. 10

Similar content being viewed by others

References

  1. Wenz, G., Han, B., Moller, A.: Cyclodextrin rotaxanes and polyrotaxanes. Chem. Rev. 106, 782–817 (2006)

    Article  CAS  Google Scholar 

  2. Terdale, S.S., Dagade, D.H., Patil, K.J.: Thermodynamic studies of drug–cyclodextrin interactions in water at 298.15 K: Promazine hydrochloride/chlorpromazine hydrochloride–CD–H2O systems. J. Phys. Chem. B 111, 13645–13652 (2007)

    Article  CAS  Google Scholar 

  3. Song, L.X., Bai, L., Xu, X.M., He, J., Pan, S.Z.: Inclusion complexation, encapsulation interaction and inclusion number in cyclodextrin chemistry. Coord. Chem. Rev. 253, 1276–1284 (2009)

    Article  CAS  Google Scholar 

  4. Frixa, C., Scobie, M., Black, S.J., Thompson, A.S., Threadgill, M.D.: Formation of a remarkably robust 2:1 complex between beta-cyclodextrin and a phenyl-substituted icosahedral carborane. Chem. Commun. 23, 2876–2877 (2002)

    Article  Google Scholar 

  5. Krause, R.W.M., Mamba, B.B., Dlamini, L.N., Durbach, S.H.: Fe–Ni nanoparticles supported on carbon nanotube–co-cyclodextrin polyurethanes for the removal of trichloroethylene in water. J. Nanopart. Res. 12, 449–456 (2010)

    Article  CAS  Google Scholar 

  6. Rekharsky, M.V., Inoue, Y.: Complexation thermodynamics of cyclodextrins. Chem. Rev. 98, 1875–1917 (1998)

    Article  CAS  Google Scholar 

  7. Connors, K.A.: Population characteristics of cyclodextrin complex stabilities in aqueous solution. J. Pharm. Sci. 84, 843–848 (1995)

    Article  CAS  Google Scholar 

  8. Connors, K.A.: Measurement of cyclodextrin complex stability constants. In: Szejtli, J., Osa, T. (eds.) Cyclodextrins. (in: Atwood, J.L., Davies, J.E., MacNicol, D.D., Vögtle, F., Lehn, J.-M. (eds.) Comprehensive Supramolecular Chemistry, Chap. 2.) Elsevier, New York (1996)

  9. Enoch, I.V.M.V., Swaminathan, M.: Spectral and photoprototropic characteristics of 4-aminobiphenyl in β-cyclodextrin. Collect. Czech. Chem. Commun. 69, 748–758 (2004)

    Article  Google Scholar 

  10. Enoch, I.V.M.V., Swaminathan, M.: Dual fluorescence and photoprototropic characteristics of 2-aminodiphenylsulphone-β-cyclodextrin inclusion complex. J. Incl. Phenom. Macrocycl. Chem. 53, 149–154 (2005)

    Article  CAS  Google Scholar 

  11. Enoch, I.V.M.V., Swaminathan, M.: Fluorimetric study on molecular recognition of β-cyclodextrin with 2-amino-9-fluorenone. J. Fluoresc. 16, 501–510 (2006)

    Article  CAS  Google Scholar 

  12. Enoch, I.V.M.V., Swaminathan, M.: Flourimetric and prototropic studies on the inclusion complexation of 2-amino and 4-aminodiphenyl ethers with β-cyclodextrin: Unusual behavior of 4-aminodiphenyl ether. J. Lumin. 127, 713–720 (2007)

    Article  CAS  Google Scholar 

  13. Panja, S., Chakravorti, S.: Dynamics of twisted intramolecular charge transfer process of 4-N,N-dimethylaminocinnamic acid in α-cyclodextrin environment. Chem. Phys. Lett. 336, 57 (2001)

    Article  CAS  Google Scholar 

  14. Bezrukova, A., Lubomska, M., Rogalski, M.: Nanoparticle mixtures of anthracene and β-cyclodextrin testing by optical spectroscopy. Rev. Adv. Mater. Sci. 20, 70–76 (2009)

    Google Scholar 

  15. Chattopadhyay, N.: Effect of cyclodextrin complexation on excited state proton transfer reactions. J. Photochem. Photobiol. A 58, 31–36 (1991)

    Article  CAS  Google Scholar 

  16. Yarozu, T., Hoshino, M., Shizuka, H.: Photoexcited inclusion complexes of beta-naphthol with alpha-, beta-, and gamma-cyclodextrins in aqueous solutions. J. Phys. Chem. 86, 4422–4426 (1982)

    Article  Google Scholar 

  17. Bortolus, P., Marconi, G., Monti, S., Mayer, B., Kohler, G., Grabner, G.: Interaction of 4-hydroxybiphenyl with cyclodextrins: Effect of complex structure on spectroscopic and photophysical properties. Chem. Eur. J. 9, 1578–1591 (2000)

    Article  Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Department of Chemistry, School of Science and Humanities, Karunya University, Coimbatore, 641 114, India

    Israel V. M. V. Enoch & Sameena Yousuf

Authors
  1. Israel V. M. V. Enoch
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Sameena Yousuf
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Israel V. M. V. Enoch.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Enoch, I.V.M.V., Yousuf, S. β-Cyclodextrin Inclusion Complexes of 2-Hydroxyfluorene and 2-Hydroxy-9-fluorenone: Differences in Stoichiometry and Excited State Prototropic Equilibrium. J Solution Chem 42, 470–484 (2013). https://doi.org/10.1007/s10953-013-9965-1

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s10953-013-9965-1

Keywords

Search

Navigation